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Hudson Technologies Inc./NY – ‘10-K’ for 12/31/20 – ‘EX-101.LAB’

On:  Friday, 3/12/21, at 5:11pm ET   ·   For:  12/31/20   ·   Accession #:  1104659-21-35666   ·   File #:  1-13412

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  As Of               Filer                 Filing    For·On·As Docs:Size             Issuer                      Filing Agent

 3/12/21  Hudson Technologies Inc./NY       10-K       12/31/20   80:6.4M                                   Toppan Merrill/FA

Annual Report   —   Form 10-K
Filing Table of Contents

Document/Exhibit                   Description                      Pages   Size 

 1: 10-K        Annual Report                                       HTML    426K 
 2: EX-10.52    Material Contract                                   HTML     33K 
 3: EX-10.53    Material Contract                                   HTML     34K 
 4: EX-10.54    Material Contract                                   HTML     30K 
 5: EX-10.55    Material Contract                                   HTML     32K 
 6: EX-10.56    Material Contract                                   HTML     31K 
 7: EX-21       Subsidiaries List                                   HTML     22K 
 8: EX-23.1     Consent of Expert or Counsel                        HTML     21K 
 9: EX-31.1     Certification -- §302 - SOA'02                      HTML     26K 
10: EX-31.2     Certification -- §302 - SOA'02                      HTML     26K 
11: EX-32.1     Certification -- §906 - SOA'02                      HTML     22K 
12: EX-32.2     Certification -- §906 - SOA'02                      HTML     22K 
19: R1          Document and Entity Information                     HTML     62K 
20: R2          Consolidated Balance Sheets                         HTML    105K 
21: R3          Consolidated Balance Sheets (Parenthetical)         HTML     43K 
22: R4          Consolidated Statements of Operations               HTML     87K 
23: R5          Consolidated Statements of Stockholders' Equity     HTML     51K 
24: R6          Consolidated Statements of Cash Flows               HTML    109K 
25: R7          Summary of Significant Accounting Policies          HTML     96K 
26: R8          Fair Value                                          HTML     27K 
27: R9          Trade accounts receivable - net                     HTML     48K 
28: R10         Inventories                                         HTML     40K 
29: R11         Property, plant and equipment                       HTML     86K 
30: R12         Leases                                              HTML     64K 
31: R13         Income taxes                                        HTML    118K 
32: R14         Goodwill and intangible assets                      HTML    102K 
33: R15         Short-term and Long-term debt                       HTML    105K 
34: R16         Commitments and contingencies                       HTML     65K 
35: R17         Share-based compensation                            HTML    134K 
36: R18         Other Income                                        HTML     25K 
37: R19         Related Party Transactions                          HTML     26K 
38: R20         Summary of Significant Accounting Policies          HTML    139K 
                (Policies)                                                       
39: R21         Summary of Significant Accounting Policies          HTML     61K 
                (Tables)                                                         
40: R22         Trade accounts receivable - net (Tables)            HTML     48K 
41: R23         Inventories (Tables)                                HTML     41K 
42: R24         Property, plant and equipment (Tables)              HTML     85K 
43: R25         Leases (Tables)                                     HTML     64K 
44: R26         Income taxes (Tables)                               HTML    118K 
45: R27         Goodwill and intangible assets (Tables)             HTML    101K 
46: R28         Short-term and Long-term debt (Tables)              HTML     82K 
47: R29         Commitments and contingencies (Tables)              HTML     64K 
48: R30         Share-based compensation (Tables)                   HTML    136K 
49: R31         Summary of Significant Accounting Policies -        HTML     31K 
                Summary of company's revenues (Details)                          
50: R32         Summary of Significant Accounting Policies -        HTML     35K 
                Summary of reconciliation of shares used to                      
                determine net income per share (Details)                         
51: R33         Summary of Significant Accounting Policies -        HTML     88K 
                Additional Information (Details)                                 
52: R34         Trade accounts receivable - net - Reserves for      HTML     29K 
                doubtful accounts (Details)                                      
53: R35         Trade accounts receivable - net - Additional        HTML     24K 
                Information (Details)                                            
54: R36         Inventories (Details)                               HTML     28K 
55: R37         Property, plant and equipment - Summary of          HTML     82K 
                Elements of property, plant and equipment                        
                (Details)                                                        
56: R38         Property, plant and equipment - Additional          HTML     28K 
                Information (Details)                                            
57: R39         Leases - Maturity of lease payments (Details)       HTML     39K 
58: R40         Leases - Balance Sheet Classification and Other     HTML     36K 
                Information (Details)                                            
59: R41         Leases - Additional Information (Details)           HTML     30K 
60: R42         Income taxes - Provision for Income Taxes           HTML     45K 
                (Details)                                                        
61: R43         Income taxes - Reconciliation of Company's Actual   HTML     43K 
                Tax Rate to U.S. Federal Statutory Rate (Details)                
62: R44         Income taxes - Elements of Deferred Income Tax      HTML     45K 
                Assets (Liabilities) (Details)                                   
63: R45         Income taxes - Additional Information (Details)     HTML     46K 
64: R46         Goodwill and intangible assets - Company's other    HTML     52K 
                intangible assets (Details)                                      
65: R47         Goodwill and intangible assets - Additional         HTML     44K 
                Information (Details)                                            
66: R48         Short-term and long-term debt (Details)             HTML     48K 
67: R49         Short-term and long-term debt - Maturities of       HTML     30K 
                long-term debt and capital lease obligations                     
                (Details)                                                        
68: R50         Short-term and long-term debt - Additional          HTML    151K 
                Information (Details)                                            
69: R51         Commitments and contingencies - Non-cancelable      HTML     59K 
                operating leases (Details)                                       
70: R52         Commitments and contingencies - Additional          HTML     23K 
                Information (Details)                                            
71: R53         Share-Based Compensation - Weighted Average         HTML     41K 
                Assumptions Used in Determining Fair Value of                    
                Share Based Awards at Grant Date by Using                        
                Black-Scholes Option Pricing Model (Details)                     
72: R54         Share-based compensation - Summary of Status of     HTML     44K 
                Company's Stock Option Plan (Details)                            
73: R55         Share-Based compensation - Weighted Average         HTML     51K 
                Contractual Life and Exercise Price (Details)                    
74: R56         Share-Based Compensation - Intrinsic Value          HTML     26K 
                (Details)                                                        
75: R57         Share-based compensation - Additional Information   HTML     52K 
                (Details)                                                        
76: R58         Other Income (Details)                              HTML     28K 
77: R59         Related Party Transactions (Details)                HTML     32K 
79: XML         IDEA XML File -- Filing Summary                      XML    132K 
78: EXCEL       IDEA Workbook of Financial Reports                  XLSX     96K 
13: EX-101.INS  XBRL Instance -- hdsn-20201231                       XML   1.98M 
15: EX-101.CAL  XBRL Calculations -- hdsn-20201231_cal               XML    173K 
16: EX-101.DEF  XBRL Definitions -- hdsn-20201231_def                XML    411K 
17: EX-101.LAB  XBRL Labels -- hdsn-20201231_lab                     XML   1.11M 
18: EX-101.PRE  XBRL Presentations -- hdsn-20201231_pre              XML    809K 
14: EX-101.SCH  XBRL Schema -- hdsn-20201231                         XSD    172K 
80: ZIP         XBRL Zipped Folder -- 0001104659-21-035666-xbrl      Zip    157K

‘EX-101.LAB’   —   XBRL Labels — hdsn-20201231_lab

This Exhibit is an XBRL XML File.

                                                                                                                                                                                
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<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="dei_EntityInteractiveDataCurrent_lbl" xml:lang="en-US"> Entity Interactive Data Current </label>
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<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="dei_EntityCentralIndexKey_lbl" xml:lang="en-US"> Entity Central Index Key </label>
<loc xlink:type="locator" xlink:href="https://xbrl.sec.gov/dei/2020/dei-2020-01-31.xsd#dei_CurrentFiscalYearEndDate" xlink:label="dei_CurrentFiscalYearEndDate"/>
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<loc xlink:type="locator" xlink:href="https://xbrl.sec.gov/dei/2020/dei-2020-01-31.xsd#dei_EntityFilerCategory" xlink:label="dei_EntityFilerCategory"/>
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<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="dei_EntityEmergingGrowthCompany_lbl" xml:lang="en-US"> Entity Emerging Growth Company </label>
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<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="dei_EntitySmallBusiness_lbl" xml:lang="en-US"> Entity Small Business </label>
<loc xlink:type="locator" xlink:href="https://xbrl.sec.gov/dei/2020/dei-2020-01-31.xsd#dei_EntityPublicFloat" xlink:label="dei_EntityPublicFloat"/>
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<loc xlink:type="locator" xlink:href="https://xbrl.sec.gov/dei/2020/dei-2020-01-31.xsd#dei_EntityWellKnownSeasonedIssuer" xlink:label="dei_EntityWellKnownSeasonedIssuer"/>
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<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="dei_EntityVoluntaryFilers_lbl" xml:lang="en-US"> Entity Voluntary Filers </label>
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<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="dei_Security12bTitle_lbl" xml:lang="en-US"> Title of 12(b) Security </label>
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<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_StatementOfFinancialPositionAbstract" xlink:label="us-gaap_StatementOfFinancialPositionAbstract"/>
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<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_AssetsAbstract_lbl" xml:lang="en-US"> Assets [Abstract] </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_AssetsAbstract_lbl" xml:lang="en-US"> Assets </label>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_AssetsCurrentAbstract" xlink:label="us-gaap_AssetsCurrentAbstract"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_AssetsCurrentAbstract" xlink:to="us-gaap_AssetsCurrentAbstract_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_AssetsCurrentAbstract_lbl" xml:lang="en-US"> Assets Current [Abstract] </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_AssetsCurrentAbstract_lbl" xml:lang="en-US"> Current assets: </label>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_CashAndCashEquivalentsAtCarryingValue" xlink:label="us-gaap_CashAndCashEquivalentsAtCarryingValue"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_CashAndCashEquivalentsAtCarryingValue" xlink:to="us-gaap_CashAndCashEquivalentsAtCarryingValue_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_CashAndCashEquivalentsAtCarryingValue_lbl" xml:lang="en-US"> Cash and Cash Equivalents, at Carrying Value </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/verboseLabel" xlink:label="us-gaap_CashAndCashEquivalentsAtCarryingValue_lbl" xml:lang="en-US"> Cash and cash equivalents </label>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_AccountsReceivableNetCurrent" xlink:label="us-gaap_AccountsReceivableNetCurrent"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_AccountsReceivableNetCurrent" xlink:to="us-gaap_AccountsReceivableNetCurrent_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_AccountsReceivableNetCurrent_lbl" xml:lang="en-US"> Accounts Receivable, Net, Current, Total </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/verboseLabel" xlink:label="us-gaap_AccountsReceivableNetCurrent_lbl" xml:lang="en-US"> Trade accounts receivable - net </label>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_InventoryNet" xlink:label="us-gaap_InventoryNet"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_InventoryNet" xlink:to="us-gaap_InventoryNet_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_InventoryNet_lbl" xml:lang="en-US"> Inventory, Net, Total </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_InventoryNet_lbl" xml:lang="en-US"> Inventories </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/totalLabel" xlink:label="us-gaap_InventoryNet_lbl" xml:lang="en-US"> Total </label>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_PrepaidExpenseAndOtherAssetsCurrent" xlink:label="us-gaap_PrepaidExpenseAndOtherAssetsCurrent"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_PrepaidExpenseAndOtherAssetsCurrent" xlink:to="us-gaap_PrepaidExpenseAndOtherAssetsCurrent_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_PrepaidExpenseAndOtherAssetsCurrent_lbl" xml:lang="en-US"> Prepaid Expense and Other Assets Current </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_PrepaidExpenseAndOtherAssetsCurrent_lbl" xml:lang="en-US"> Prepaid expenses and other current assets </label>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_AssetsCurrent" xlink:label="us-gaap_AssetsCurrent"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_AssetsCurrent" xlink:to="us-gaap_AssetsCurrent_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_AssetsCurrent_lbl" xml:lang="en-US"> Assets, Current, Total </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/totalLabel" xlink:label="us-gaap_AssetsCurrent_lbl" xml:lang="en-US"> Total current assets </label>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_PropertyPlantAndEquipmentNet" xlink:label="us-gaap_PropertyPlantAndEquipmentNet"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_PropertyPlantAndEquipmentNet" xlink:to="us-gaap_PropertyPlantAndEquipmentNet_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_PropertyPlantAndEquipmentNet_lbl" xml:lang="en-US"> Property, Plant and Equipment, Net, Total </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_PropertyPlantAndEquipmentNet_lbl" xml:lang="en-US"> Property, plant and equipment, less accumulated depreciation </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/totalLabel" xlink:label="us-gaap_PropertyPlantAndEquipmentNet_lbl" xml:lang="en-US"> Total </label>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_Goodwill" xlink:label="us-gaap_Goodwill"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_Goodwill" xlink:to="us-gaap_Goodwill_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_Goodwill_lbl" xml:lang="en-US"> Goodwill </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/verboseLabel" xlink:label="us-gaap_Goodwill_lbl" xml:lang="en-US"> Goodwill </label>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_IntangibleAssetsNetExcludingGoodwill" xlink:label="us-gaap_IntangibleAssetsNetExcludingGoodwill"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_IntangibleAssetsNetExcludingGoodwill" xlink:to="us-gaap_IntangibleAssetsNetExcludingGoodwill_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_IntangibleAssetsNetExcludingGoodwill_lbl" xml:lang="en-US"> Intangible Assets, Net (Excluding Goodwill), Total </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_IntangibleAssetsNetExcludingGoodwill_lbl" xml:lang="en-US"> Intangible assets, less accumulated amortization </label>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_OperatingLeaseRightOfUseAsset" xlink:label="us-gaap_OperatingLeaseRightOfUseAsset"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_OperatingLeaseRightOfUseAsset" xlink:to="us-gaap_OperatingLeaseRightOfUseAsset_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_OperatingLeaseRightOfUseAsset_lbl" xml:lang="en-US"> Operating Lease, Right-of-Use Asset </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/verboseLabel" xlink:label="us-gaap_OperatingLeaseRightOfUseAsset_lbl" xml:lang="en-US"> Right of use asset </label>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_OtherAssetsNoncurrent" xlink:label="us-gaap_OtherAssetsNoncurrent"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_OtherAssetsNoncurrent" xlink:to="us-gaap_OtherAssetsNoncurrent_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_OtherAssetsNoncurrent_lbl" xml:lang="en-US"> Other Assets Noncurrent </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_OtherAssetsNoncurrent_lbl" xml:lang="en-US"> Other assets </label>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_Assets" xlink:label="us-gaap_Assets"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_Assets" xlink:to="us-gaap_Assets_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_Assets_lbl" xml:lang="en-US"> Assets, Total </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/totalLabel" xlink:label="us-gaap_Assets_lbl" xml:lang="en-US"> Total Assets </label>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_LiabilitiesAndStockholdersEquityAbstract" xlink:label="us-gaap_LiabilitiesAndStockholdersEquityAbstract"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_LiabilitiesAndStockholdersEquityAbstract" xlink:to="us-gaap_LiabilitiesAndStockholdersEquityAbstract_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_LiabilitiesAndStockholdersEquityAbstract_lbl" xml:lang="en-US"> Liabilities and Stockholders Equity [Abstract] </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_LiabilitiesAndStockholdersEquityAbstract_lbl" xml:lang="en-US"> Liabilities and Stockholders' Equity </label>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_LiabilitiesCurrentAbstract" xlink:label="us-gaap_LiabilitiesCurrentAbstract"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_LiabilitiesCurrentAbstract" xlink:to="us-gaap_LiabilitiesCurrentAbstract_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_LiabilitiesCurrentAbstract_lbl" xml:lang="en-US"> Liabilities Current [Abstract] </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_LiabilitiesCurrentAbstract_lbl" xml:lang="en-US"> Current liabilities: </label>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_AccountsPayableTradeCurrent" xlink:label="us-gaap_AccountsPayableTradeCurrent"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_AccountsPayableTradeCurrent" xlink:to="us-gaap_AccountsPayableTradeCurrent_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_AccountsPayableTradeCurrent_lbl" xml:lang="en-US"> Accounts Payable, Trade, Current </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/verboseLabel" xlink:label="us-gaap_AccountsPayableTradeCurrent_lbl" xml:lang="en-US"> Trade accounts payable </label>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_AccruedLiabilitiesAndOtherLiabilities" xlink:label="us-gaap_AccruedLiabilitiesAndOtherLiabilities"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_AccruedLiabilitiesAndOtherLiabilities" xlink:to="us-gaap_AccruedLiabilitiesAndOtherLiabilities_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_AccruedLiabilitiesAndOtherLiabilities_lbl" xml:lang="en-US"> Accrued Liabilities and Other Liabilities, Total </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_AccruedLiabilitiesAndOtherLiabilities_lbl" xml:lang="en-US"> Accrued expenses and other current liabilities </label>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_EmployeeRelatedLiabilitiesCurrent" xlink:label="us-gaap_EmployeeRelatedLiabilitiesCurrent"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_EmployeeRelatedLiabilitiesCurrent" xlink:to="us-gaap_EmployeeRelatedLiabilitiesCurrent_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_EmployeeRelatedLiabilitiesCurrent_lbl" xml:lang="en-US"> Employee Related Liabilities Current </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/verboseLabel" xlink:label="us-gaap_EmployeeRelatedLiabilitiesCurrent_lbl" xml:lang="en-US"> Accrued payroll </label>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_LongTermDebtCurrent" xlink:label="us-gaap_LongTermDebtCurrent"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_LongTermDebtCurrent" xlink:to="us-gaap_LongTermDebtCurrent_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_LongTermDebtCurrent_lbl" xml:lang="en-US"> Long-term Debt, Current Maturities </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_LongTermDebtCurrent_lbl" xml:lang="en-US"> Current maturities of long-term debt </label>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ShortTermBorrowings" xlink:label="us-gaap_ShortTermBorrowings"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_ShortTermBorrowings" xlink:to="us-gaap_ShortTermBorrowings_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_ShortTermBorrowings_lbl" xml:lang="en-US"> Short-term Debt </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/verboseLabel" xlink:label="us-gaap_ShortTermBorrowings_lbl" xml:lang="en-US"> Short-term debt </label>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_LiabilitiesCurrent" xlink:label="us-gaap_LiabilitiesCurrent"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_LiabilitiesCurrent" xlink:to="us-gaap_LiabilitiesCurrent_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_LiabilitiesCurrent_lbl" xml:lang="en-US"> Liabilities, Current, Total </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/totalLabel" xlink:label="us-gaap_LiabilitiesCurrent_lbl" xml:lang="en-US"> Total current liabilities </label>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DeferredIncomeTaxLiabilitiesNet" xlink:label="us-gaap_DeferredIncomeTaxLiabilitiesNet"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_DeferredIncomeTaxLiabilitiesNet" xlink:to="us-gaap_DeferredIncomeTaxLiabilitiesNet_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_DeferredIncomeTaxLiabilitiesNet_lbl" xml:lang="en-US"> Deferred Income Tax Liabilities, Net </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_DeferredIncomeTaxLiabilitiesNet_lbl" xml:lang="en-US"> Deferred tax liability </label>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_OperatingLeaseLiabilityNoncurrent" xlink:label="us-gaap_OperatingLeaseLiabilityNoncurrent"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_OperatingLeaseLiabilityNoncurrent" xlink:to="us-gaap_OperatingLeaseLiabilityNoncurrent_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_OperatingLeaseLiabilityNoncurrent_lbl" xml:lang="en-US"> Operating Lease, Liability, Noncurrent </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_OperatingLeaseLiabilityNoncurrent_lbl" xml:lang="en-US"> Long-term lease liabilities </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/verboseLabel" xlink:label="us-gaap_OperatingLeaseLiabilityNoncurrent_lbl" xml:lang="en-US"> Long-term lease liabilities </label>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_LongTermDebtNoncurrent" xlink:label="us-gaap_LongTermDebtNoncurrent"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_LongTermDebtNoncurrent" xlink:to="us-gaap_LongTermDebtNoncurrent_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_LongTermDebtNoncurrent_lbl" xml:lang="en-US"> Long-term Debt, Excluding Current Maturities, Total </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/totalLabel" xlink:label="us-gaap_LongTermDebtNoncurrent_lbl" xml:lang="en-US"> Subtotal </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/verboseLabel" xlink:label="us-gaap_LongTermDebtNoncurrent_lbl" xml:lang="en-US"> Long-term debt, less current maturities, net of deferred financing costs </label>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_Liabilities" xlink:label="us-gaap_Liabilities"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_Liabilities" xlink:to="us-gaap_Liabilities_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_Liabilities_lbl" xml:lang="en-US"> Liabilities, Total </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/totalLabel" xlink:label="us-gaap_Liabilities_lbl" xml:lang="en-US"> Total Liabilities </label>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_CommitmentsAndContingencies" xlink:label="us-gaap_CommitmentsAndContingencies"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_CommitmentsAndContingencies" xlink:to="us-gaap_CommitmentsAndContingencies_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_CommitmentsAndContingencies_lbl" xml:lang="en-US"> Commitments and Contingencies </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/verboseLabel" xlink:label="us-gaap_CommitmentsAndContingencies_lbl" xml:lang="en-US"> Commitments and contingencies </label>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_StockholdersEquityAbstract" xlink:label="us-gaap_StockholdersEquityAbstract"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_StockholdersEquityAbstract" xlink:to="us-gaap_StockholdersEquityAbstract_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_StockholdersEquityAbstract_lbl" xml:lang="en-US"> Consolidated Statements of Stockholders' Equity </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/verboseLabel" xlink:label="us-gaap_StockholdersEquityAbstract_lbl" xml:lang="en-US"> Stockholders' equity: </label>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_PreferredStockValue" xlink:label="us-gaap_PreferredStockValue"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_PreferredStockValue" xlink:to="us-gaap_PreferredStockValue_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_PreferredStockValue_lbl" xml:lang="en-US"> Preferred Stock Value </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/verboseLabel" xlink:label="us-gaap_PreferredStockValue_lbl" xml:lang="en-US"> Preferred stock, shares authorized 5,000,000: Series A Convertible preferred stock, $0.01 par value ($100 liquidation preference value); shares authorized 150,000; none issued or outstanding </label>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_CommonStockValue" xlink:label="us-gaap_CommonStockValue"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_CommonStockValue" xlink:to="us-gaap_CommonStockValue_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_CommonStockValue_lbl" xml:lang="en-US"> Common Stock Value </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/verboseLabel" xlink:label="us-gaap_CommonStockValue_lbl" xml:lang="en-US"> Common stock, $0.01 par value; shares authorized 100,000,000; issued and outstanding: 43,347,887 and 42,628,560, respectively </label>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_AdditionalPaidInCapital" xlink:label="us-gaap_AdditionalPaidInCapital"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_AdditionalPaidInCapital" xlink:to="us-gaap_AdditionalPaidInCapital_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_AdditionalPaidInCapital_lbl" xml:lang="en-US"> Additional Paid In Capital </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_AdditionalPaidInCapital_lbl" xml:lang="en-US"> Additional paid-in capital </label>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_RetainedEarningsAccumulatedDeficit" xlink:label="us-gaap_RetainedEarningsAccumulatedDeficit"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_RetainedEarningsAccumulatedDeficit" xlink:to="us-gaap_RetainedEarningsAccumulatedDeficit_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_RetainedEarningsAccumulatedDeficit_lbl" xml:lang="en-US"> Retained Earnings Accumulated Deficit </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/verboseLabel" xlink:label="us-gaap_RetainedEarningsAccumulatedDeficit_lbl" xml:lang="en-US"> Accumulated deficit </label>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_StockholdersEquity" xlink:label="us-gaap_StockholdersEquity"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_StockholdersEquity" xlink:to="us-gaap_StockholdersEquity_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_StockholdersEquity_lbl" xml:lang="en-US"> Stockholders' Equity Attributable to Parent </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/periodEndLabel" xlink:label="us-gaap_StockholdersEquity_lbl" xml:lang="en-US"> Balance </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/periodStartLabel" xlink:label="us-gaap_StockholdersEquity_lbl" xml:lang="en-US"> Balance </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/totalLabel" xlink:label="us-gaap_StockholdersEquity_lbl" xml:lang="en-US"> Total Stockholders' Equity </label>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_LiabilitiesAndStockholdersEquity" xlink:label="us-gaap_LiabilitiesAndStockholdersEquity"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_LiabilitiesAndStockholdersEquity" xlink:to="us-gaap_LiabilitiesAndStockholdersEquity_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_LiabilitiesAndStockholdersEquity_lbl" xml:lang="en-US"> Liabilities and Stockholders Equity </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/totalLabel" xlink:label="us-gaap_LiabilitiesAndStockholdersEquity_lbl" xml:lang="en-US"> Total Liabilities and Stockholders' Equity </label>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_StatementClassOfStockAxis" xlink:label="us-gaap_StatementClassOfStockAxis"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_StatementClassOfStockAxis" xlink:to="us-gaap_StatementClassOfStockAxis_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_StatementClassOfStockAxis_lbl" xml:lang="en-US"> Class of Stock [Axis] </label>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ClassOfStockDomain" xlink:label="us-gaap_ClassOfStockDomain"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_ClassOfStockDomain" xlink:to="us-gaap_ClassOfStockDomain_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_ClassOfStockDomain_lbl" xml:lang="en-US"> Class Of Stock [Domain] </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_ClassOfStockDomain_lbl" xml:lang="en-US"> Class of Stock [Domain] </label>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_PreferredStockMember" xlink:label="us-gaap_PreferredStockMember"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_PreferredStockMember" xlink:to="us-gaap_PreferredStockMember_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_PreferredStockMember_lbl" xml:lang="en-US"> Preferred Stock [Member] </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_PreferredStockMember_lbl" xml:lang="en-US"> Preferred Stock </label>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_SeriesAPreferredStockMember" xlink:label="us-gaap_SeriesAPreferredStockMember"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_SeriesAPreferredStockMember" xlink:to="us-gaap_SeriesAPreferredStockMember_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_SeriesAPreferredStockMember_lbl" xml:lang="en-US"> Series A Preferred Stock [Member] </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_SeriesAPreferredStockMember_lbl" xml:lang="en-US"> Series A Convertible Preferred Stock </label>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_PreferredStockParOrStatedValuePerShare" xlink:label="us-gaap_PreferredStockParOrStatedValuePerShare"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_PreferredStockParOrStatedValuePerShare" xlink:to="us-gaap_PreferredStockParOrStatedValuePerShare_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_PreferredStockParOrStatedValuePerShare_lbl" xml:lang="en-US"> Preferred Stock Par Or Stated Value Per Share </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_PreferredStockParOrStatedValuePerShare_lbl" xml:lang="en-US"> Preferred stock, par value </label>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_PreferredStockLiquidationPreferenceValue" xlink:label="us-gaap_PreferredStockLiquidationPreferenceValue"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_PreferredStockLiquidationPreferenceValue" xlink:to="us-gaap_PreferredStockLiquidationPreferenceValue_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_PreferredStockLiquidationPreferenceValue_lbl" xml:lang="en-US"> Preferred Stock, Liquidation Preference, Value </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/verboseLabel" xlink:label="us-gaap_PreferredStockLiquidationPreferenceValue_lbl" xml:lang="en-US"> Preferred stock, liquidation preference value </label>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_PreferredStockSharesAuthorized" xlink:label="us-gaap_PreferredStockSharesAuthorized"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_PreferredStockSharesAuthorized" xlink:to="us-gaap_PreferredStockSharesAuthorized_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_PreferredStockSharesAuthorized_lbl" xml:lang="en-US"> Preferred Stock Shares Authorized </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_PreferredStockSharesAuthorized_lbl" xml:lang="en-US"> Preferred stock, shares authorized </label>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_PreferredStockSharesIssued" xlink:label="us-gaap_PreferredStockSharesIssued"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_PreferredStockSharesIssued" xlink:to="us-gaap_PreferredStockSharesIssued_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_PreferredStockSharesIssued_lbl" xml:lang="en-US"> Preferred Stock Shares Issued </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_PreferredStockSharesIssued_lbl" xml:lang="en-US"> Preferred stock, issued </label>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_PreferredStockSharesOutstanding" xlink:label="us-gaap_PreferredStockSharesOutstanding"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_PreferredStockSharesOutstanding" xlink:to="us-gaap_PreferredStockSharesOutstanding_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_PreferredStockSharesOutstanding_lbl" xml:lang="en-US"> Preferred Stock Shares Outstanding </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_PreferredStockSharesOutstanding_lbl" xml:lang="en-US"> Preferred stock, outstanding </label>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_CommonStockParOrStatedValuePerShare" xlink:label="us-gaap_CommonStockParOrStatedValuePerShare"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_CommonStockParOrStatedValuePerShare" xlink:to="us-gaap_CommonStockParOrStatedValuePerShare_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_CommonStockParOrStatedValuePerShare_lbl" xml:lang="en-US"> Common Stock, Par Or Stated Value Per Share </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_CommonStockParOrStatedValuePerShare_lbl" xml:lang="en-US"> Common stock, par value </label>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_CommonStockSharesAuthorized" xlink:label="us-gaap_CommonStockSharesAuthorized"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_CommonStockSharesAuthorized" xlink:to="us-gaap_CommonStockSharesAuthorized_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_CommonStockSharesAuthorized_lbl" xml:lang="en-US"> Common Stock Shares Authorized </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_CommonStockSharesAuthorized_lbl" xml:lang="en-US"> Common stock, shares authorized </label>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_CommonStockSharesIssued" xlink:label="us-gaap_CommonStockSharesIssued"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_CommonStockSharesIssued" xlink:to="us-gaap_CommonStockSharesIssued_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_CommonStockSharesIssued_lbl" xml:lang="en-US"> Common Stock, Shares, Issued </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_CommonStockSharesIssued_lbl" xml:lang="en-US"> Common stock, issued </label>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_CommonStockSharesOutstanding" xlink:label="us-gaap_CommonStockSharesOutstanding"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_CommonStockSharesOutstanding" xlink:to="us-gaap_CommonStockSharesOutstanding_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_CommonStockSharesOutstanding_lbl" xml:lang="en-US"> Common Stock Shares Outstanding </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/verboseLabel" xlink:label="us-gaap_CommonStockSharesOutstanding_lbl" xml:lang="en-US"> Common stock, outstanding </label>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_IncomeStatementAbstract" xlink:label="us-gaap_IncomeStatementAbstract"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_IncomeStatementAbstract" xlink:to="us-gaap_IncomeStatementAbstract_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_IncomeStatementAbstract_lbl" xml:lang="en-US"> Consolidated Statements of Operations </label>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_Revenues" xlink:label="us-gaap_Revenues"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_Revenues" xlink:to="us-gaap_Revenues_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_Revenues_lbl" xml:lang="en-US"> Revenues </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_Revenues_lbl" xml:lang="en-US"> Revenues </label>
<loc xlink:type="locator" xlink:href="hdsn-20201231.xsd#hdsn_CostOfSalesExcludingCostOfNetRealizableValueAdjustment" xlink:label="hdsn_CostOfSalesExcludingCostOfNetRealizableValueAdjustment"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="hdsn_CostOfSalesExcludingCostOfNetRealizableValueAdjustment" xlink:to="hdsn_CostOfSalesExcludingCostOfNetRealizableValueAdjustment_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:label="hdsn_CostOfSalesExcludingCostOfNetRealizableValueAdjustment_lbl" xml:lang="en-US"> The aggregate costs related to goods produced and sold and services rendered by an entity excluding cost of new realizable value adjustment during the reporting period. This excludes costs incurred during the reporting period related to financial services rendered and other revenue generating activities. </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="hdsn_CostOfSalesExcludingCostOfNetRealizableValueAdjustment_lbl" xml:lang="en-US"> Cost of Sales Excluding Cost of Net Realizable Value Adjustment </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/verboseLabel" xlink:label="hdsn_CostOfSalesExcludingCostOfNetRealizableValueAdjustment_lbl" xml:lang="en-US"> Cost of sales </label>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_GrossProfit" xlink:label="us-gaap_GrossProfit"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_GrossProfit" xlink:to="us-gaap_GrossProfit_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_GrossProfit_lbl" xml:lang="en-US"> Gross Profit </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/totalLabel" xlink:label="us-gaap_GrossProfit_lbl" xml:lang="en-US"> Gross profit </label>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_OperatingExpensesAbstract" xlink:label="us-gaap_OperatingExpensesAbstract"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_OperatingExpensesAbstract" xlink:to="us-gaap_OperatingExpensesAbstract_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_OperatingExpensesAbstract_lbl" xml:lang="en-US"> Operating Expenses [Abstract] </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_OperatingExpensesAbstract_lbl" xml:lang="en-US"> Operating expenses: </label>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_SellingGeneralAndAdministrativeExpense" xlink:label="us-gaap_SellingGeneralAndAdministrativeExpense"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_SellingGeneralAndAdministrativeExpense" xlink:to="us-gaap_SellingGeneralAndAdministrativeExpense_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_SellingGeneralAndAdministrativeExpense_lbl" xml:lang="en-US"> Selling, General and Administrative Expense </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/verboseLabel" xlink:label="us-gaap_SellingGeneralAndAdministrativeExpense_lbl" xml:lang="en-US"> Selling, general and administrative </label>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_AdjustmentForAmortization" xlink:label="us-gaap_AdjustmentForAmortization"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_AdjustmentForAmortization" xlink:to="us-gaap_AdjustmentForAmortization_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_AdjustmentForAmortization_lbl" xml:lang="en-US"> Amortization </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/verboseLabel" xlink:label="us-gaap_AdjustmentForAmortization_lbl" xml:lang="en-US"> Amortization </label>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_OperatingExpenses" xlink:label="us-gaap_OperatingExpenses"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_OperatingExpenses" xlink:to="us-gaap_OperatingExpenses_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_OperatingExpenses_lbl" xml:lang="en-US"> Operating Expenses </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/totalLabel" xlink:label="us-gaap_OperatingExpenses_lbl" xml:lang="en-US"> Total operating expenses </label>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_OperatingIncomeLoss" xlink:label="us-gaap_OperatingIncomeLoss"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_OperatingIncomeLoss" xlink:to="us-gaap_OperatingIncomeLoss_lbl"/>
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<label xlink:type="resource" xlink:role="http://www.xbrl.org/2009/role/negatedLabel" xlink:label="us-gaap_InterestExpense_lbl" xml:lang="en-US"> Interest expense </label>
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<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_IncomeTaxExpenseBenefit_lbl" xml:lang="en-US"> Income Tax Expense (Benefit) </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_IncomeTaxExpenseBenefit_lbl" xml:lang="en-US"> Income Tax Expense (Benefit) </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/totalLabel" xlink:label="us-gaap_IncomeTaxExpenseBenefit_lbl" xml:lang="en-US"> (Benefit) expense for income taxes </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/verboseLabel" xlink:label="us-gaap_IncomeTaxExpenseBenefit_lbl" xml:lang="en-US"> Income tax (benefit) expense </label>
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<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_NetIncomeLoss_lbl" xml:lang="en-US"> Net Income (Loss) Attributable to Parent </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/totalLabel" xlink:label="us-gaap_NetIncomeLoss_lbl" xml:lang="en-US"> Net loss </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/verboseLabel" xlink:label="us-gaap_NetIncomeLoss_lbl" xml:lang="en-US"> Net loss </label>
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<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_EarningsPerShareBasic_lbl" xml:lang="en-US"> Earnings Per Share, Basic </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_EarningsPerShareBasic_lbl" xml:lang="en-US"> Net loss per common share - Basic </label>
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<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_EarningsPerShareDiluted_lbl" xml:lang="en-US"> Earnings Per Share, Diluted </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_EarningsPerShareDiluted_lbl" xml:lang="en-US"> Net loss per common share - Diluted </label>
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<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_WeightedAverageNumberOfSharesOutstandingBasic_lbl" xml:lang="en-US"> Weighted Average Number of Shares Outstanding, Basic </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_WeightedAverageNumberOfSharesOutstandingBasic_lbl" xml:lang="en-US"> Weighted average number of shares outstanding - Basic </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/verboseLabel" xlink:label="us-gaap_WeightedAverageNumberOfSharesOutstandingBasic_lbl" xml:lang="en-US"> Weighted average number of shares - basic </label>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_WeightedAverageNumberOfDilutedSharesOutstanding" xlink:label="us-gaap_WeightedAverageNumberOfDilutedSharesOutstanding"/>
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<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_WeightedAverageNumberOfDilutedSharesOutstanding_lbl" xml:lang="en-US"> Weighted Average Number of Shares Outstanding, Diluted </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_WeightedAverageNumberOfDilutedSharesOutstanding_lbl" xml:lang="en-US"> Weighted average number of shares outstanding - Diluted </label>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_SharesOutstanding" xlink:label="us-gaap_SharesOutstanding"/>
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<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_SharesOutstanding_lbl" xml:lang="en-US"> Shares, Outstanding </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/periodEndLabel" xlink:label="us-gaap_SharesOutstanding_lbl" xml:lang="en-US"> Balance (in shares) </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/periodStartLabel" xlink:label="us-gaap_SharesOutstanding_lbl" xml:lang="en-US"> Balance (in shares) </label>
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<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/verboseLabel" xlink:label="us-gaap_StockIssuedDuringPeriodValueStockOptionsExercised_lbl" xml:lang="en-US"> Issuance of common stock upon exercise of stock options </label>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_StockIssuedDuringPeriodSharesStockOptionsExercised" xlink:label="us-gaap_StockIssuedDuringPeriodSharesStockOptionsExercised"/>
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<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_StockIssuedDuringPeriodSharesStockOptionsExercised_lbl" xml:lang="en-US"> Share-Based Compensation Arrangement By Share-Based Payment Award, Options, Exercises In Period </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2009/role/negatedLabel" xlink:label="us-gaap_StockIssuedDuringPeriodSharesStockOptionsExercised_lbl" xml:lang="en-US"> -Exercised </label>
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<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_StockIssuedDuringPeriodValueIssuedForServices" xlink:label="us-gaap_StockIssuedDuringPeriodValueIssuedForServices"/>
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<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_AdjustmentsToAdditionalPaidInCapitalSharebasedCompensationRequisiteServicePeriodRecognitionValue" xlink:label="us-gaap_AdjustmentsToAdditionalPaidInCapitalSharebasedCompensationRequisiteServicePeriodRecognitionValue"/>
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<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_ProfitLoss_lbl" xml:lang="en-US"> Net Income (Loss), Including Portion Attributable to Noncontrolling Interest </label>
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<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_AmortizationOfIntangibleAssets_lbl" xml:lang="en-US"> Amortization of Intangible Assets </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/verboseLabel" xlink:label="us-gaap_AmortizationOfIntangibleAssets_lbl" xml:lang="en-US"> Amortization of intangible assets </label>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_GainOnBusinessInterruptionInsuranceRecovery" xlink:label="us-gaap_GainOnBusinessInterruptionInsuranceRecovery"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_GainOnBusinessInterruptionInsuranceRecovery" xlink:to="us-gaap_GainOnBusinessInterruptionInsuranceRecovery_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_GainOnBusinessInterruptionInsuranceRecovery_lbl" xml:lang="en-US"> Gain on Business Interruption Insurance Recovery </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2009/role/negatedLabel" xlink:label="us-gaap_GainOnBusinessInterruptionInsuranceRecovery_lbl" xml:lang="en-US"> Gain on insurance proceeds </label>
<loc xlink:type="locator" xlink:href="hdsn-20201231.xsd#hdsn_LowerOfCostOrNetRealizableValueAdjustment" xlink:label="hdsn_LowerOfCostOrNetRealizableValueAdjustment"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="hdsn_LowerOfCostOrNetRealizableValueAdjustment" xlink:to="hdsn_LowerOfCostOrNetRealizableValueAdjustment_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:label="hdsn_LowerOfCostOrNetRealizableValueAdjustment_lbl" xml:lang="en-US"> Amount of expense related to lower of cost or net realizable value adjustment incurred during the year. </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="hdsn_LowerOfCostOrNetRealizableValueAdjustment_lbl" xml:lang="en-US"> Lower Of Cost Or Net Realizable Value Adjustment </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="hdsn_LowerOfCostOrNetRealizableValueAdjustment_lbl" xml:lang="en-US"> Lower of cost or net realizable value inventory adjustment </label>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ProvisionForDoubtfulAccounts" xlink:label="us-gaap_ProvisionForDoubtfulAccounts"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_ProvisionForDoubtfulAccounts" xlink:to="us-gaap_ProvisionForDoubtfulAccounts_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_ProvisionForDoubtfulAccounts_lbl" xml:lang="en-US"> Provision for Doubtful Accounts </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/verboseLabel" xlink:label="us-gaap_ProvisionForDoubtfulAccounts_lbl" xml:lang="en-US"> Allowance for doubtful accounts </label>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_AmortizationOfFinancingCosts" xlink:label="us-gaap_AmortizationOfFinancingCosts"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_AmortizationOfFinancingCosts" xlink:to="us-gaap_AmortizationOfFinancingCosts_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_AmortizationOfFinancingCosts_lbl" xml:lang="en-US"> Amortization of Financing Costs </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/verboseLabel" xlink:label="us-gaap_AmortizationOfFinancingCosts_lbl" xml:lang="en-US"> Amortization of deferred finance costs </label>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ShareBasedCompensation" xlink:label="us-gaap_ShareBasedCompensation"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_ShareBasedCompensation" xlink:to="us-gaap_ShareBasedCompensation_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_ShareBasedCompensation_lbl" xml:lang="en-US"> Share Based Compensation </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_ShareBasedCompensation_lbl" xml:lang="en-US"> Value of share-based payment arrangements </label>
<loc xlink:type="locator" xlink:href="hdsn-20201231.xsd#hdsn_WriteOffOfIntangibleAssets" xlink:label="hdsn_WriteOffOfIntangibleAssets"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="hdsn_WriteOffOfIntangibleAssets" xlink:to="hdsn_WriteOffOfIntangibleAssets_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:label="hdsn_WriteOffOfIntangibleAssets_lbl" xml:lang="en-US"> Amount of intangible asset written off during the period. </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="hdsn_WriteOffOfIntangibleAssets_lbl" xml:lang="en-US"> Write-Off of Intangible Assets </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="hdsn_WriteOffOfIntangibleAssets_lbl" xml:lang="en-US"> Write-off of intangible assets </label>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DeferredIncomeTaxExpenseBenefit" xlink:label="us-gaap_DeferredIncomeTaxExpenseBenefit"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_DeferredIncomeTaxExpenseBenefit" xlink:to="us-gaap_DeferredIncomeTaxExpenseBenefit_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_DeferredIncomeTaxExpenseBenefit_lbl" xml:lang="en-US"> Deferred Income Tax Expense (Benefit) </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/totalLabel" xlink:label="us-gaap_DeferredIncomeTaxExpenseBenefit_lbl" xml:lang="en-US"> Deferred Income Tax Expense (Benefit), Total </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/verboseLabel" xlink:label="us-gaap_DeferredIncomeTaxExpenseBenefit_lbl" xml:lang="en-US"> Deferred tax expense </label>
<loc xlink:type="locator" xlink:href="hdsn-20201231.xsd#hdsn_NoncashAdjustmentOfCylinderDeposits" xlink:label="hdsn_NoncashAdjustmentOfCylinderDeposits"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="hdsn_NoncashAdjustmentOfCylinderDeposits" xlink:to="hdsn_NoncashAdjustmentOfCylinderDeposits_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:label="hdsn_NoncashAdjustmentOfCylinderDeposits_lbl" xml:lang="en-US"> Amount of non cash adjustment of cylinder deposits for the particular period which the entity has incurred. </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="hdsn_NoncashAdjustmentOfCylinderDeposits_lbl" xml:lang="en-US"> Noncash Adjustment Of Cylinder Deposits </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/verboseLabel" xlink:label="hdsn_NoncashAdjustmentOfCylinderDeposits_lbl" xml:lang="en-US"> Non-cash adjustment of cylinder deposits </label>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_IncreaseDecreaseInOperatingCapitalAbstract" xlink:label="us-gaap_IncreaseDecreaseInOperatingCapitalAbstract"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_IncreaseDecreaseInOperatingCapitalAbstract" xlink:to="us-gaap_IncreaseDecreaseInOperatingCapitalAbstract_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_IncreaseDecreaseInOperatingCapitalAbstract_lbl" xml:lang="en-US"> Increase Decrease In Operating Capital [Abstract] </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/verboseLabel" xlink:label="us-gaap_IncreaseDecreaseInOperatingCapitalAbstract_lbl" xml:lang="en-US"> Changes in assets and liabilities: </label>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_IncreaseDecreaseInAccountsReceivable" xlink:label="us-gaap_IncreaseDecreaseInAccountsReceivable"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_IncreaseDecreaseInAccountsReceivable" xlink:to="us-gaap_IncreaseDecreaseInAccountsReceivable_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_IncreaseDecreaseInAccountsReceivable_lbl" xml:lang="en-US"> Increase Decrease In Accounts Receivable </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2009/role/negatedLabel" xlink:label="us-gaap_IncreaseDecreaseInAccountsReceivable_lbl" xml:lang="en-US"> Trade accounts receivable </label>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_IncreaseDecreaseInInventories" xlink:label="us-gaap_IncreaseDecreaseInInventories"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_IncreaseDecreaseInInventories" xlink:to="us-gaap_IncreaseDecreaseInInventories_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_IncreaseDecreaseInInventories_lbl" xml:lang="en-US"> Increase Decrease In Inventories </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2009/role/negatedLabel" xlink:label="us-gaap_IncreaseDecreaseInInventories_lbl" xml:lang="en-US"> Inventories </label>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_IncreaseDecreaseInPrepaidDeferredExpenseAndOtherAssets" xlink:label="us-gaap_IncreaseDecreaseInPrepaidDeferredExpenseAndOtherAssets"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_IncreaseDecreaseInPrepaidDeferredExpenseAndOtherAssets" xlink:to="us-gaap_IncreaseDecreaseInPrepaidDeferredExpenseAndOtherAssets_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_IncreaseDecreaseInPrepaidDeferredExpenseAndOtherAssets_lbl" xml:lang="en-US"> Increase Decrease In Prepaid Deferred Expense and Other Assets </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2009/role/negatedLabel" xlink:label="us-gaap_IncreaseDecreaseInPrepaidDeferredExpenseAndOtherAssets_lbl" xml:lang="en-US"> Prepaid and other assets </label>
<loc xlink:type="locator" xlink:href="hdsn-20201231.xsd#hdsn_IncreaseDecreaseInLeaseObligations" xlink:label="hdsn_IncreaseDecreaseInLeaseObligations"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="hdsn_IncreaseDecreaseInLeaseObligations" xlink:to="hdsn_IncreaseDecreaseInLeaseObligations_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:label="hdsn_IncreaseDecreaseInLeaseObligations_lbl" xml:lang="en-US"> The increase (decrease) during the reporting period in the lease obligations. </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="hdsn_IncreaseDecreaseInLeaseObligations_lbl" xml:lang="en-US"> Increase (Decrease) in Lease Obligations </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/verboseLabel" xlink:label="hdsn_IncreaseDecreaseInLeaseObligations_lbl" xml:lang="en-US"> Lease obligations </label>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_IncreaseDecreaseInAccruedIncomeTaxesPayable" xlink:label="us-gaap_IncreaseDecreaseInAccruedIncomeTaxesPayable"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_IncreaseDecreaseInAccruedIncomeTaxesPayable" xlink:to="us-gaap_IncreaseDecreaseInAccruedIncomeTaxesPayable_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_IncreaseDecreaseInAccruedIncomeTaxesPayable_lbl" xml:lang="en-US"> Increase (Decrease) in Income Taxes Payable </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/verboseLabel" xlink:label="us-gaap_IncreaseDecreaseInAccruedIncomeTaxesPayable_lbl" xml:lang="en-US"> Income taxes receivable/payable </label>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_IncreaseDecreaseInAccountsPayableAndAccruedLiabilities" xlink:label="us-gaap_IncreaseDecreaseInAccountsPayableAndAccruedLiabilities"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_IncreaseDecreaseInAccountsPayableAndAccruedLiabilities" xlink:to="us-gaap_IncreaseDecreaseInAccountsPayableAndAccruedLiabilities_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_IncreaseDecreaseInAccountsPayableAndAccruedLiabilities_lbl" xml:lang="en-US"> Increase Decrease In Accounts Payable and Accrued Liabilities </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/verboseLabel" xlink:label="us-gaap_IncreaseDecreaseInAccountsPayableAndAccruedLiabilities_lbl" xml:lang="en-US"> Accounts payable and accrued expenses </label>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_NetCashProvidedByUsedInOperatingActivities" xlink:label="us-gaap_NetCashProvidedByUsedInOperatingActivities"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_NetCashProvidedByUsedInOperatingActivities" xlink:to="us-gaap_NetCashProvidedByUsedInOperatingActivities_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_NetCashProvidedByUsedInOperatingActivities_lbl" xml:lang="en-US"> Net Cash Provided by (Used in) Operating Activities </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/totalLabel" xlink:label="us-gaap_NetCashProvidedByUsedInOperatingActivities_lbl" xml:lang="en-US"> Cash provided by operating activities </label>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_NetCashProvidedByUsedInInvestingActivitiesAbstract" xlink:label="us-gaap_NetCashProvidedByUsedInInvestingActivitiesAbstract"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_NetCashProvidedByUsedInInvestingActivitiesAbstract" xlink:to="us-gaap_NetCashProvidedByUsedInInvestingActivitiesAbstract_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_NetCashProvidedByUsedInInvestingActivitiesAbstract_lbl" xml:lang="en-US"> Net Cash Provided by (Used in) Investing Activities [Abstract] </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/verboseLabel" xlink:label="us-gaap_NetCashProvidedByUsedInInvestingActivitiesAbstract_lbl" xml:lang="en-US"> Cash flows from investing activities: </label>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_PaymentsToAcquirePropertyPlantAndEquipment" xlink:label="us-gaap_PaymentsToAcquirePropertyPlantAndEquipment"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_PaymentsToAcquirePropertyPlantAndEquipment" xlink:to="us-gaap_PaymentsToAcquirePropertyPlantAndEquipment_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_PaymentsToAcquirePropertyPlantAndEquipment_lbl" xml:lang="en-US"> Payments To Acquire Property Plant and Equipment </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2009/role/negatedLabel" xlink:label="us-gaap_PaymentsToAcquirePropertyPlantAndEquipment_lbl" xml:lang="en-US"> Additions to property, plant, and equipment </label>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ProceedsFromLifeInsurancePolicies" xlink:label="us-gaap_ProceedsFromLifeInsurancePolicies"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_ProceedsFromLifeInsurancePolicies" xlink:to="us-gaap_ProceedsFromLifeInsurancePolicies_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_ProceedsFromLifeInsurancePolicies_lbl" xml:lang="en-US"> Proceeds from Life Insurance Policy </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_ProceedsFromLifeInsurancePolicies_lbl" xml:lang="en-US"> Proceeds from Insurance Policy </label>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_NetCashProvidedByUsedInInvestingActivities" xlink:label="us-gaap_NetCashProvidedByUsedInInvestingActivities"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_NetCashProvidedByUsedInInvestingActivities" xlink:to="us-gaap_NetCashProvidedByUsedInInvestingActivities_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_NetCashProvidedByUsedInInvestingActivities_lbl" xml:lang="en-US"> Net Cash Provided by (Used in) Investing Activities </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/totalLabel" xlink:label="us-gaap_NetCashProvidedByUsedInInvestingActivities_lbl" xml:lang="en-US"> Cash used in investing activities </label>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_NetCashProvidedByUsedInFinancingActivitiesContinuingOperationsAbstract" xlink:label="us-gaap_NetCashProvidedByUsedInFinancingActivitiesContinuingOperationsAbstract"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_NetCashProvidedByUsedInFinancingActivitiesContinuingOperationsAbstract" xlink:to="us-gaap_NetCashProvidedByUsedInFinancingActivitiesContinuingOperationsAbstract_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_NetCashProvidedByUsedInFinancingActivitiesContinuingOperationsAbstract_lbl" xml:lang="en-US"> Net Cash Provided by (Used in) Financing Activities, Continuing Operations [Abstract] </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/verboseLabel" xlink:label="us-gaap_NetCashProvidedByUsedInFinancingActivitiesContinuingOperationsAbstract_lbl" xml:lang="en-US"> Cash flows from financing activities: </label>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ProceedsFromIssuanceOfCommonStock" xlink:label="us-gaap_ProceedsFromIssuanceOfCommonStock"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_ProceedsFromIssuanceOfCommonStock" xlink:to="us-gaap_ProceedsFromIssuanceOfCommonStock_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_ProceedsFromIssuanceOfCommonStock_lbl" xml:lang="en-US"> Proceeds from Issuance of Common Stock </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_ProceedsFromIssuanceOfCommonStock_lbl" xml:lang="en-US"> Net proceeds from issuances of common stock and exercises of stock options </label>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ProceedsFromIssuanceOfUnsecuredDebt" xlink:label="us-gaap_ProceedsFromIssuanceOfUnsecuredDebt"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_ProceedsFromIssuanceOfUnsecuredDebt" xlink:to="us-gaap_ProceedsFromIssuanceOfUnsecuredDebt_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_ProceedsFromIssuanceOfUnsecuredDebt_lbl" xml:lang="en-US"> Proceeds from Issuance of Unsecured Debt </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_ProceedsFromIssuanceOfUnsecuredDebt_lbl" xml:lang="en-US"> Borrowing - Paycheck Protection Program </label>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_PaymentsOfMergerRelatedCostsFinancingActivities" xlink:label="us-gaap_PaymentsOfMergerRelatedCostsFinancingActivities"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_PaymentsOfMergerRelatedCostsFinancingActivities" xlink:to="us-gaap_PaymentsOfMergerRelatedCostsFinancingActivities_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_PaymentsOfMergerRelatedCostsFinancingActivities_lbl" xml:lang="en-US"> Payments of Merger Related Costs, Financing Activities </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2009/role/negatedLabel" xlink:label="us-gaap_PaymentsOfMergerRelatedCostsFinancingActivities_lbl" xml:lang="en-US"> Payment of deferred financing costs </label>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ProceedsFromRepaymentsOfShortTermDebt" xlink:label="us-gaap_ProceedsFromRepaymentsOfShortTermDebt"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_ProceedsFromRepaymentsOfShortTermDebt" xlink:to="us-gaap_ProceedsFromRepaymentsOfShortTermDebt_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_ProceedsFromRepaymentsOfShortTermDebt_lbl" xml:lang="en-US"> Proceeds From Repayments Of Short Term Debt </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_ProceedsFromRepaymentsOfShortTermDebt_lbl" xml:lang="en-US"> Repayment of short-term debt </label>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_RepaymentsOfLongTermDebt" xlink:label="us-gaap_RepaymentsOfLongTermDebt"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_RepaymentsOfLongTermDebt" xlink:to="us-gaap_RepaymentsOfLongTermDebt_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_RepaymentsOfLongTermDebt_lbl" xml:lang="en-US"> Repayments Of Long Term Debt </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2009/role/negatedLabel" xlink:label="us-gaap_RepaymentsOfLongTermDebt_lbl" xml:lang="en-US"> Repayment of long-term debt </label>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_NetCashProvidedByUsedInFinancingActivities" xlink:label="us-gaap_NetCashProvidedByUsedInFinancingActivities"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_NetCashProvidedByUsedInFinancingActivities" xlink:to="us-gaap_NetCashProvidedByUsedInFinancingActivities_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_NetCashProvidedByUsedInFinancingActivities_lbl" xml:lang="en-US"> Net Cash Provided by (Used in) Financing Activities </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/totalLabel" xlink:label="us-gaap_NetCashProvidedByUsedInFinancingActivities_lbl" xml:lang="en-US"> Cash used in financing activities </label>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsPeriodIncreaseDecreaseExcludingExchangeRateEffect" xlink:label="us-gaap_CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsPeriodIncreaseDecreaseExcludingExchangeRateEffect"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsPeriodIncreaseDecreaseExcludingExchangeRateEffect" xlink:to="us-gaap_CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsPeriodIncreaseDecreaseExcludingExchangeRateEffect_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsPeriodIncreaseDecreaseExcludingExchangeRateEffect_lbl" xml:lang="en-US"> Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents, Period Increase (Decrease), Excluding Exchange Rate Effect </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/totalLabel" xlink:label="us-gaap_CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsPeriodIncreaseDecreaseExcludingExchangeRateEffect_lbl" xml:lang="en-US"> (Decrease) increase in cash and cash equivalents </label>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents" xlink:label="us-gaap_CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents" xlink:to="us-gaap_CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents_lbl" xml:lang="en-US"> Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/periodEndLabel" xlink:label="us-gaap_CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents_lbl" xml:lang="en-US"> Cash and cash equivalents at end of period </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/periodStartLabel" xlink:label="us-gaap_CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents_lbl" xml:lang="en-US"> Cash and cash equivalents at beginning of period </label>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_SupplementalCashFlowInformationAbstract" xlink:label="us-gaap_SupplementalCashFlowInformationAbstract"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_SupplementalCashFlowInformationAbstract" xlink:to="us-gaap_SupplementalCashFlowInformationAbstract_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_SupplementalCashFlowInformationAbstract_lbl" xml:lang="en-US"> Supplemental Cash Flow Information [Abstract] </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_SupplementalCashFlowInformationAbstract_lbl" xml:lang="en-US"> Supplemental Disclosure of Cash Flow Information: </label>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_InterestPaidNet" xlink:label="us-gaap_InterestPaidNet"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_InterestPaidNet" xlink:to="us-gaap_InterestPaidNet_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_InterestPaidNet_lbl" xml:lang="en-US"> Interest Paid, Net </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/verboseLabel" xlink:label="us-gaap_InterestPaidNet_lbl" xml:lang="en-US"> Cash paid during period for interest </label>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ProceedsFromIncomeTaxRefunds" xlink:label="us-gaap_ProceedsFromIncomeTaxRefunds"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_ProceedsFromIncomeTaxRefunds" xlink:to="us-gaap_ProceedsFromIncomeTaxRefunds_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_ProceedsFromIncomeTaxRefunds_lbl" xml:lang="en-US"> Proceeds from Income Tax Refunds </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2009/role/negatedLabel" xlink:label="us-gaap_ProceedsFromIncomeTaxRefunds_lbl" xml:lang="en-US"> Refund received for income taxes - net </label>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_AccountingPoliciesAbstract" xlink:label="us-gaap_AccountingPoliciesAbstract"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_AccountingPoliciesAbstract" xlink:to="us-gaap_AccountingPoliciesAbstract_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_AccountingPoliciesAbstract_lbl" xml:lang="en-US"> Summary of Significant Accounting Policies </label>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_SignificantAccountingPoliciesTextBlock" xlink:label="us-gaap_SignificantAccountingPoliciesTextBlock"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_SignificantAccountingPoliciesTextBlock" xlink:to="us-gaap_SignificantAccountingPoliciesTextBlock_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_SignificantAccountingPoliciesTextBlock_lbl" xml:lang="en-US"> Significant Accounting Policies [Text Block] </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/verboseLabel" xlink:label="us-gaap_SignificantAccountingPoliciesTextBlock_lbl" xml:lang="en-US"> Summary of Significant Accounting Policies </label>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_FairValueDisclosuresAbstract" xlink:label="us-gaap_FairValueDisclosuresAbstract"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_FairValueDisclosuresAbstract" xlink:to="us-gaap_FairValueDisclosuresAbstract_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_FairValueDisclosuresAbstract_lbl" xml:lang="en-US"> Fair Value </label>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_FairValueMeasurementInputsDisclosureTextBlock" xlink:label="us-gaap_FairValueMeasurementInputsDisclosureTextBlock"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_FairValueMeasurementInputsDisclosureTextBlock" xlink:to="us-gaap_FairValueMeasurementInputsDisclosureTextBlock_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_FairValueMeasurementInputsDisclosureTextBlock_lbl" xml:lang="en-US"> Fair Value, Measurement Inputs, Disclosure [Text Block] </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/verboseLabel" xlink:label="us-gaap_FairValueMeasurementInputsDisclosureTextBlock_lbl" xml:lang="en-US"> Fair Value </label>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ReceivablesAbstract" xlink:label="us-gaap_ReceivablesAbstract"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_ReceivablesAbstract" xlink:to="us-gaap_ReceivablesAbstract_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_ReceivablesAbstract_lbl" xml:lang="en-US"> Trade accounts receivable - net </label>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_LoansNotesTradeAndOtherReceivablesDisclosureTextBlock" xlink:label="us-gaap_LoansNotesTradeAndOtherReceivablesDisclosureTextBlock"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_LoansNotesTradeAndOtherReceivablesDisclosureTextBlock" xlink:to="us-gaap_LoansNotesTradeAndOtherReceivablesDisclosureTextBlock_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_LoansNotesTradeAndOtherReceivablesDisclosureTextBlock_lbl" xml:lang="en-US"> Loans, Notes, Trade and Other Receivables Disclosure [Text Block] </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/verboseLabel" xlink:label="us-gaap_LoansNotesTradeAndOtherReceivablesDisclosureTextBlock_lbl" xml:lang="en-US"> Trade accounts receivable - net </label>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_InventoryDisclosureAbstract" xlink:label="us-gaap_InventoryDisclosureAbstract"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_InventoryDisclosureAbstract" xlink:to="us-gaap_InventoryDisclosureAbstract_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_InventoryDisclosureAbstract_lbl" xml:lang="en-US"> Inventories </label>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_InventoryDisclosureTextBlock" xlink:label="us-gaap_InventoryDisclosureTextBlock"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_InventoryDisclosureTextBlock" xlink:to="us-gaap_InventoryDisclosureTextBlock_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_InventoryDisclosureTextBlock_lbl" xml:lang="en-US"> Inventory Disclosure [Text Block] </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/verboseLabel" xlink:label="us-gaap_InventoryDisclosureTextBlock_lbl" xml:lang="en-US"> Inventories </label>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_PropertyPlantAndEquipmentAbstract" xlink:label="us-gaap_PropertyPlantAndEquipmentAbstract"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_PropertyPlantAndEquipmentAbstract" xlink:to="us-gaap_PropertyPlantAndEquipmentAbstract_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_PropertyPlantAndEquipmentAbstract_lbl" xml:lang="en-US"> Property, plant and equipment </label>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_PropertyPlantAndEquipmentDisclosureTextBlock" xlink:label="us-gaap_PropertyPlantAndEquipmentDisclosureTextBlock"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_PropertyPlantAndEquipmentDisclosureTextBlock" xlink:to="us-gaap_PropertyPlantAndEquipmentDisclosureTextBlock_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_PropertyPlantAndEquipmentDisclosureTextBlock_lbl" xml:lang="en-US"> Property, Plant and Equipment Disclosure [Text Block] </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/verboseLabel" xlink:label="us-gaap_PropertyPlantAndEquipmentDisclosureTextBlock_lbl" xml:lang="en-US"> Property, plant and equipment </label>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_LeasesAbstract" xlink:label="us-gaap_LeasesAbstract"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_LeasesAbstract" xlink:to="us-gaap_LeasesAbstract_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_LeasesAbstract_lbl" xml:lang="en-US"> Leases </label>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_LesseeOperatingLeasesTextBlock" xlink:label="us-gaap_LesseeOperatingLeasesTextBlock"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_LesseeOperatingLeasesTextBlock" xlink:to="us-gaap_LesseeOperatingLeasesTextBlock_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_LesseeOperatingLeasesTextBlock_lbl" xml:lang="en-US"> Lessee, Operating Leases [Text Block] </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/verboseLabel" xlink:label="us-gaap_LesseeOperatingLeasesTextBlock_lbl" xml:lang="en-US"> Leases </label>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_IncomeTaxDisclosureAbstract" xlink:label="us-gaap_IncomeTaxDisclosureAbstract"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_IncomeTaxDisclosureAbstract" xlink:to="us-gaap_IncomeTaxDisclosureAbstract_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_IncomeTaxDisclosureAbstract_lbl" xml:lang="en-US"> Income taxes </label>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_IncomeTaxDisclosureTextBlock" xlink:label="us-gaap_IncomeTaxDisclosureTextBlock"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_IncomeTaxDisclosureTextBlock" xlink:to="us-gaap_IncomeTaxDisclosureTextBlock_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_IncomeTaxDisclosureTextBlock_lbl" xml:lang="en-US"> Income Tax Disclosure [Text Block] </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/verboseLabel" xlink:label="us-gaap_IncomeTaxDisclosureTextBlock_lbl" xml:lang="en-US"> Income taxes </label>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_GoodwillAndIntangibleAssetsDisclosureAbstract" xlink:label="us-gaap_GoodwillAndIntangibleAssetsDisclosureAbstract"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_GoodwillAndIntangibleAssetsDisclosureAbstract" xlink:to="us-gaap_GoodwillAndIntangibleAssetsDisclosureAbstract_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_GoodwillAndIntangibleAssetsDisclosureAbstract_lbl" xml:lang="en-US"> Goodwill and intangible assets </label>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_GoodwillAndIntangibleAssetsDisclosureTextBlock" xlink:label="us-gaap_GoodwillAndIntangibleAssetsDisclosureTextBlock"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_GoodwillAndIntangibleAssetsDisclosureTextBlock" xlink:to="us-gaap_GoodwillAndIntangibleAssetsDisclosureTextBlock_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_GoodwillAndIntangibleAssetsDisclosureTextBlock_lbl" xml:lang="en-US"> Goodwill and Intangible Assets Disclosure [Text Block] </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/verboseLabel" xlink:label="us-gaap_GoodwillAndIntangibleAssetsDisclosureTextBlock_lbl" xml:lang="en-US"> Goodwill and intangible assets </label>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DebtDisclosureAbstract" xlink:label="us-gaap_DebtDisclosureAbstract"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_DebtDisclosureAbstract" xlink:to="us-gaap_DebtDisclosureAbstract_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_DebtDisclosureAbstract_lbl" xml:lang="en-US"> Short-term and Long-term debt </label>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DebtDisclosureTextBlock" xlink:label="us-gaap_DebtDisclosureTextBlock"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_DebtDisclosureTextBlock" xlink:to="us-gaap_DebtDisclosureTextBlock_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_DebtDisclosureTextBlock_lbl" xml:lang="en-US"> Debt Disclosure [Text Block] </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_DebtDisclosureTextBlock_lbl" xml:lang="en-US"> Short-term and Long-term debt </label>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_CommitmentsAndContingenciesDisclosureAbstract" xlink:label="us-gaap_CommitmentsAndContingenciesDisclosureAbstract"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_CommitmentsAndContingenciesDisclosureAbstract" xlink:to="us-gaap_CommitmentsAndContingenciesDisclosureAbstract_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_CommitmentsAndContingenciesDisclosureAbstract_lbl" xml:lang="en-US"> Commitments and contingencies </label>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_CommitmentsAndContingenciesDisclosureTextBlock" xlink:label="us-gaap_CommitmentsAndContingenciesDisclosureTextBlock"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_CommitmentsAndContingenciesDisclosureTextBlock" xlink:to="us-gaap_CommitmentsAndContingenciesDisclosureTextBlock_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_CommitmentsAndContingenciesDisclosureTextBlock_lbl" xml:lang="en-US"> Commitments and Contingencies Disclosure [Text Block] </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/verboseLabel" xlink:label="us-gaap_CommitmentsAndContingenciesDisclosureTextBlock_lbl" xml:lang="en-US"> Commitments and contingencies </label>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ShareBasedCompensationAbstract" xlink:label="us-gaap_ShareBasedCompensationAbstract"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_ShareBasedCompensationAbstract" xlink:to="us-gaap_ShareBasedCompensationAbstract_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_ShareBasedCompensationAbstract_lbl" xml:lang="en-US"> Share-based compensation </label>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DisclosureOfCompensationRelatedCostsShareBasedPaymentsTextBlock" xlink:label="us-gaap_DisclosureOfCompensationRelatedCostsShareBasedPaymentsTextBlock"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_DisclosureOfCompensationRelatedCostsShareBasedPaymentsTextBlock" xlink:to="us-gaap_DisclosureOfCompensationRelatedCostsShareBasedPaymentsTextBlock_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_DisclosureOfCompensationRelatedCostsShareBasedPaymentsTextBlock_lbl" xml:lang="en-US"> Disclosure Of Compensation Related Costs Share Based Payments [Text Block] </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_DisclosureOfCompensationRelatedCostsShareBasedPaymentsTextBlock_lbl" xml:lang="en-US"> Share-based compensation </label>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_OtherIncomeAndExpensesAbstract" xlink:label="us-gaap_OtherIncomeAndExpensesAbstract"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_OtherIncomeAndExpensesAbstract" xlink:to="us-gaap_OtherIncomeAndExpensesAbstract_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_OtherIncomeAndExpensesAbstract_lbl" xml:lang="en-US"> Other Income </label>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_OtherIncomeAndOtherExpenseDisclosureTextBlock" xlink:label="us-gaap_OtherIncomeAndOtherExpenseDisclosureTextBlock"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_OtherIncomeAndOtherExpenseDisclosureTextBlock" xlink:to="us-gaap_OtherIncomeAndOtherExpenseDisclosureTextBlock_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_OtherIncomeAndOtherExpenseDisclosureTextBlock_lbl" xml:lang="en-US"> Other Income and Other Expense Disclosure [Text Block] </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/verboseLabel" xlink:label="us-gaap_OtherIncomeAndOtherExpenseDisclosureTextBlock_lbl" xml:lang="en-US"> Other Income </label>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_RelatedPartyTransactionsAbstract" xlink:label="us-gaap_RelatedPartyTransactionsAbstract"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_RelatedPartyTransactionsAbstract" xlink:to="us-gaap_RelatedPartyTransactionsAbstract_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_RelatedPartyTransactionsAbstract_lbl" xml:lang="en-US"> Related Party Transactions </label>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_RelatedPartyTransactionsDisclosureTextBlock" xlink:label="us-gaap_RelatedPartyTransactionsDisclosureTextBlock"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_RelatedPartyTransactionsDisclosureTextBlock" xlink:to="us-gaap_RelatedPartyTransactionsDisclosureTextBlock_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_RelatedPartyTransactionsDisclosureTextBlock_lbl" xml:lang="en-US"> Related Party Transactions Disclosure [Text Block] </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_RelatedPartyTransactionsDisclosureTextBlock_lbl" xml:lang="en-US"> Related Party Transactions </label>
<loc xlink:type="locator" xlink:href="hdsn-20201231.xsd#hdsn_NatureOfOperationsPolicyTextBlock" xlink:label="hdsn_NatureOfOperationsPolicyTextBlock"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="hdsn_NatureOfOperationsPolicyTextBlock" xlink:to="hdsn_NatureOfOperationsPolicyTextBlock_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:label="hdsn_NatureOfOperationsPolicyTextBlock_lbl" xml:lang="en-US"> Nature Of Operations Policy </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="hdsn_NatureOfOperationsPolicyTextBlock_lbl" xml:lang="en-US"> Nature Of Operations [Policy Text Block] </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/verboseLabel" xlink:label="hdsn_NatureOfOperationsPolicyTextBlock_lbl" xml:lang="en-US"> Business </label>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ConsolidationPolicyTextBlock" xlink:label="us-gaap_ConsolidationPolicyTextBlock"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_ConsolidationPolicyTextBlock" xlink:to="us-gaap_ConsolidationPolicyTextBlock_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_ConsolidationPolicyTextBlock_lbl" xml:lang="en-US"> Consolidation, Policy [Policy Text Block] </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/verboseLabel" xlink:label="us-gaap_ConsolidationPolicyTextBlock_lbl" xml:lang="en-US"> Consolidation </label>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_FairValueOfFinancialInstrumentsPolicy" xlink:label="us-gaap_FairValueOfFinancialInstrumentsPolicy"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_FairValueOfFinancialInstrumentsPolicy" xlink:to="us-gaap_FairValueOfFinancialInstrumentsPolicy_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_FairValueOfFinancialInstrumentsPolicy_lbl" xml:lang="en-US"> Fair Value Of Financial Instruments, Policy [Policy Text Block] </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_FairValueOfFinancialInstrumentsPolicy_lbl" xml:lang="en-US"> Fair Value of Financial Instruments </label>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ConcentrationRiskCreditRisk" xlink:label="us-gaap_ConcentrationRiskCreditRisk"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_ConcentrationRiskCreditRisk" xlink:to="us-gaap_ConcentrationRiskCreditRisk_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_ConcentrationRiskCreditRisk_lbl" xml:lang="en-US"> Concentration Risk, Credit Risk, Policy [Policy Text Block] </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_ConcentrationRiskCreditRisk_lbl" xml:lang="en-US"> Credit Risk </label>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_CashAndCashEquivalentsPolicyTextBlock" xlink:label="us-gaap_CashAndCashEquivalentsPolicyTextBlock"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_CashAndCashEquivalentsPolicyTextBlock" xlink:to="us-gaap_CashAndCashEquivalentsPolicyTextBlock_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_CashAndCashEquivalentsPolicyTextBlock_lbl" xml:lang="en-US"> Cash and Cash Equivalents, Policy [Policy Text Block] </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_CashAndCashEquivalentsPolicyTextBlock_lbl" xml:lang="en-US"> Cash and Cash Equivalents </label>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_InventoryPolicyTextBlock" xlink:label="us-gaap_InventoryPolicyTextBlock"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_InventoryPolicyTextBlock" xlink:to="us-gaap_InventoryPolicyTextBlock_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_InventoryPolicyTextBlock_lbl" xml:lang="en-US"> Inventory, Policy [Policy Text Block] </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/verboseLabel" xlink:label="us-gaap_InventoryPolicyTextBlock_lbl" xml:lang="en-US"> Inventories </label>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_PropertyPlantAndEquipmentPolicyTextBlock" xlink:label="us-gaap_PropertyPlantAndEquipmentPolicyTextBlock"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_PropertyPlantAndEquipmentPolicyTextBlock" xlink:to="us-gaap_PropertyPlantAndEquipmentPolicyTextBlock_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_PropertyPlantAndEquipmentPolicyTextBlock_lbl" xml:lang="en-US"> Property, Plant and Equipment, Policy [Policy Text Block] </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_PropertyPlantAndEquipmentPolicyTextBlock_lbl" xml:lang="en-US"> Property, Plant and Equipment </label>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_GoodwillAndIntangibleAssetsPolicyTextBlock" xlink:label="us-gaap_GoodwillAndIntangibleAssetsPolicyTextBlock"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_GoodwillAndIntangibleAssetsPolicyTextBlock" xlink:to="us-gaap_GoodwillAndIntangibleAssetsPolicyTextBlock_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_GoodwillAndIntangibleAssetsPolicyTextBlock_lbl" xml:lang="en-US"> Goodwill and Intangible Assets, Policy [Policy Text Block] </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/verboseLabel" xlink:label="us-gaap_GoodwillAndIntangibleAssetsPolicyTextBlock_lbl" xml:lang="en-US"> Goodwill </label>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_LesseeLeasesPolicyTextBlock" xlink:label="us-gaap_LesseeLeasesPolicyTextBlock"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_LesseeLeasesPolicyTextBlock" xlink:to="us-gaap_LesseeLeasesPolicyTextBlock_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_LesseeLeasesPolicyTextBlock_lbl" xml:lang="en-US"> Lessee, Leases [Policy Text Block] </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_LesseeLeasesPolicyTextBlock_lbl" xml:lang="en-US"> Leases </label>
<loc xlink:type="locator" xlink:href="hdsn-20201231.xsd#hdsn_CylinderDepositLiabilityPolicyTextBlock" xlink:label="hdsn_CylinderDepositLiabilityPolicyTextBlock"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="hdsn_CylinderDepositLiabilityPolicyTextBlock" xlink:to="hdsn_CylinderDepositLiabilityPolicyTextBlock_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:label="hdsn_CylinderDepositLiabilityPolicyTextBlock_lbl" xml:lang="en-US"> Disclosure of accounting policy Cylinder Deposit Liability. </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="hdsn_CylinderDepositLiabilityPolicyTextBlock_lbl" xml:lang="en-US"> Cylinder Deposit Liability [Policy Text Block] </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="hdsn_CylinderDepositLiabilityPolicyTextBlock_lbl" xml:lang="en-US"> Cylinder Deposit Liability </label>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_RevenueFromContractWithCustomerPolicyTextBlock" xlink:label="us-gaap_RevenueFromContractWithCustomerPolicyTextBlock"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_RevenueFromContractWithCustomerPolicyTextBlock" xlink:to="us-gaap_RevenueFromContractWithCustomerPolicyTextBlock_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_RevenueFromContractWithCustomerPolicyTextBlock_lbl" xml:lang="en-US"> Revenue from Contract with Customer [Policy Text Block] </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_RevenueFromContractWithCustomerPolicyTextBlock_lbl" xml:lang="en-US"> Revenues and Cost of Sales </label>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_IncomeTaxPolicyTextBlock" xlink:label="us-gaap_IncomeTaxPolicyTextBlock"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_IncomeTaxPolicyTextBlock" xlink:to="us-gaap_IncomeTaxPolicyTextBlock_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_IncomeTaxPolicyTextBlock_lbl" xml:lang="en-US"> Income Tax, Policy [Policy Text Block] </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_IncomeTaxPolicyTextBlock_lbl" xml:lang="en-US"> Income Taxes </label>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_EarningsPerSharePolicyTextBlock" xlink:label="us-gaap_EarningsPerSharePolicyTextBlock"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_EarningsPerSharePolicyTextBlock" xlink:to="us-gaap_EarningsPerSharePolicyTextBlock_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_EarningsPerSharePolicyTextBlock_lbl" xml:lang="en-US"> Earnings Per Share, Policy [Policy Text Block] </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_EarningsPerSharePolicyTextBlock_lbl" xml:lang="en-US"> Income per Common and Equivalent Shares </label>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_UseOfEstimates" xlink:label="us-gaap_UseOfEstimates"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_UseOfEstimates" xlink:to="us-gaap_UseOfEstimates_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_UseOfEstimates_lbl" xml:lang="en-US"> Use Of Estimates, Policy [Policy Text Block] </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_UseOfEstimates_lbl" xml:lang="en-US"> Estimates and Risks </label>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ImpairmentOrDisposalOfLongLivedAssetsPolicyTextBlock" xlink:label="us-gaap_ImpairmentOrDisposalOfLongLivedAssetsPolicyTextBlock"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_ImpairmentOrDisposalOfLongLivedAssetsPolicyTextBlock" xlink:to="us-gaap_ImpairmentOrDisposalOfLongLivedAssetsPolicyTextBlock_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_ImpairmentOrDisposalOfLongLivedAssetsPolicyTextBlock_lbl" xml:lang="en-US"> Impairment Or Disposal Of Long-Lived Assets, Policy [Policy Text Block] </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_ImpairmentOrDisposalOfLongLivedAssetsPolicyTextBlock_lbl" xml:lang="en-US"> Impairment of Long-lived Assets </label>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_NewAccountingPronouncementsPolicyPolicyTextBlock" xlink:label="us-gaap_NewAccountingPronouncementsPolicyPolicyTextBlock"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_NewAccountingPronouncementsPolicyPolicyTextBlock" xlink:to="us-gaap_NewAccountingPronouncementsPolicyPolicyTextBlock_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_NewAccountingPronouncementsPolicyPolicyTextBlock_lbl" xml:lang="en-US"> New Accounting Pronouncements, Policy [Policy Text Block] </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/verboseLabel" xlink:label="us-gaap_NewAccountingPronouncementsPolicyPolicyTextBlock_lbl" xml:lang="en-US"> Recent Accounting Pronouncements </label>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ReconciliationOfRevenueFromSegmentsToConsolidatedTextBlock" xlink:label="us-gaap_ReconciliationOfRevenueFromSegmentsToConsolidatedTextBlock"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_ReconciliationOfRevenueFromSegmentsToConsolidatedTextBlock" xlink:to="us-gaap_ReconciliationOfRevenueFromSegmentsToConsolidatedTextBlock_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_ReconciliationOfRevenueFromSegmentsToConsolidatedTextBlock_lbl" xml:lang="en-US"> Reconciliation Of Revenue From Segments To Consolidated [Text Block] </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/verboseLabel" xlink:label="us-gaap_ReconciliationOfRevenueFromSegmentsToConsolidatedTextBlock_lbl" xml:lang="en-US"> Schedule of Company's revenues derived from product and related sales </label>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ScheduleOfEarningsPerShareBasicAndDilutedTableTextBlock" xlink:label="us-gaap_ScheduleOfEarningsPerShareBasicAndDilutedTableTextBlock"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_ScheduleOfEarningsPerShareBasicAndDilutedTableTextBlock" xlink:to="us-gaap_ScheduleOfEarningsPerShareBasicAndDilutedTableTextBlock_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_ScheduleOfEarningsPerShareBasicAndDilutedTableTextBlock_lbl" xml:lang="en-US"> Schedule of Earnings Per Share, Basic and Diluted [Table Text Block] </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/verboseLabel" xlink:label="us-gaap_ScheduleOfEarningsPerShareBasicAndDilutedTableTextBlock_lbl" xml:lang="en-US"> Schedule of reconciliation of shares used to determine net income per share </label>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ScheduleOfAccountsNotesLoansAndFinancingReceivableTextBlock" xlink:label="us-gaap_ScheduleOfAccountsNotesLoansAndFinancingReceivableTextBlock"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_ScheduleOfAccountsNotesLoansAndFinancingReceivableTextBlock" xlink:to="us-gaap_ScheduleOfAccountsNotesLoansAndFinancingReceivableTextBlock_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_ScheduleOfAccountsNotesLoansAndFinancingReceivableTextBlock_lbl" xml:lang="en-US"> Schedule of Accounts, Notes, Loans and Financing Receivable [Table Text Block] </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/verboseLabel" xlink:label="us-gaap_ScheduleOfAccountsNotesLoansAndFinancingReceivableTextBlock_lbl" xml:lang="en-US"> Schedule of Accounts, Notes, Loans and Financing Receivable </label>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ScheduleOfInventoryNoncurrentTableTextBlock" xlink:label="us-gaap_ScheduleOfInventoryNoncurrentTableTextBlock"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_ScheduleOfInventoryNoncurrentTableTextBlock" xlink:to="us-gaap_ScheduleOfInventoryNoncurrentTableTextBlock_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_ScheduleOfInventoryNoncurrentTableTextBlock_lbl" xml:lang="en-US"> Schedule of Inventory, Noncurrent [Table Text Block] </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_ScheduleOfInventoryNoncurrentTableTextBlock_lbl" xml:lang="en-US"> Schedule of inventories </label>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_PropertyPlantAndEquipmentTextBlock" xlink:label="us-gaap_PropertyPlantAndEquipmentTextBlock"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_PropertyPlantAndEquipmentTextBlock" xlink:to="us-gaap_PropertyPlantAndEquipmentTextBlock_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_PropertyPlantAndEquipmentTextBlock_lbl" xml:lang="en-US"> Property, Plant and Equipment [Table Text Block] </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_PropertyPlantAndEquipmentTextBlock_lbl" xml:lang="en-US"> Schedule of elements of property, plant and equipment </label>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_LesseeOperatingLeaseLiabilityMaturityTableTextBlock" xlink:label="us-gaap_LesseeOperatingLeaseLiabilityMaturityTableTextBlock"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_LesseeOperatingLeaseLiabilityMaturityTableTextBlock" xlink:to="us-gaap_LesseeOperatingLeaseLiabilityMaturityTableTextBlock_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_LesseeOperatingLeaseLiabilityMaturityTableTextBlock_lbl" xml:lang="en-US"> Schedule of the amount, timing and uncertainty of cash flows arising from the Company's operating leases </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_LesseeOperatingLeaseLiabilityMaturityTableTextBlock_lbl" xml:lang="en-US"> Schedule of maturity of lease payments </label>
<loc xlink:type="locator" xlink:href="hdsn-20201231.xsd#hdsn_ScheduleOfOperatingLeaseInBalanceSheetClassificationTableTextBlock" xlink:label="hdsn_ScheduleOfOperatingLeaseInBalanceSheetClassificationTableTextBlock"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="hdsn_ScheduleOfOperatingLeaseInBalanceSheetClassificationTableTextBlock" xlink:to="hdsn_ScheduleOfOperatingLeaseInBalanceSheetClassificationTableTextBlock_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:label="hdsn_ScheduleOfOperatingLeaseInBalanceSheetClassificationTableTextBlock_lbl" xml:lang="en-US"> Tabular disclosure of Schedule of Operating Lease in balance Sheet Classification. </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="hdsn_ScheduleOfOperatingLeaseInBalanceSheetClassificationTableTextBlock_lbl" xml:lang="en-US"> Schedule of Operating Lease in balance Sheet Classification [Table Text Block] </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/verboseLabel" xlink:label="hdsn_ScheduleOfOperatingLeaseInBalanceSheetClassificationTableTextBlock_lbl" xml:lang="en-US"> Schedule of balance sheet classification of lease liabilities </label>
<loc xlink:type="locator" xlink:href="hdsn-20201231.xsd#hdsn_ScheduleOfOperatingLeaseOtherInformationTableTextBlock" xlink:label="hdsn_ScheduleOfOperatingLeaseOtherInformationTableTextBlock"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="hdsn_ScheduleOfOperatingLeaseOtherInformationTableTextBlock" xlink:to="hdsn_ScheduleOfOperatingLeaseOtherInformationTableTextBlock_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:label="hdsn_ScheduleOfOperatingLeaseOtherInformationTableTextBlock_lbl" xml:lang="en-US"> Tabular disclosure of Schedule of Operating Lease Other Information </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="hdsn_ScheduleOfOperatingLeaseOtherInformationTableTextBlock_lbl" xml:lang="en-US"> Schedule of Operating Lease Other Information [Table Text Block] </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/verboseLabel" xlink:label="hdsn_ScheduleOfOperatingLeaseOtherInformationTableTextBlock_lbl" xml:lang="en-US"> Schedule of other information of operating leases </label>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ScheduleOfComponentsOfIncomeTaxExpenseBenefitTableTextBlock" xlink:label="us-gaap_ScheduleOfComponentsOfIncomeTaxExpenseBenefitTableTextBlock"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_ScheduleOfComponentsOfIncomeTaxExpenseBenefitTableTextBlock" xlink:to="us-gaap_ScheduleOfComponentsOfIncomeTaxExpenseBenefitTableTextBlock_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_ScheduleOfComponentsOfIncomeTaxExpenseBenefitTableTextBlock_lbl" xml:lang="en-US"> Schedule of Components of Income Tax Expense (Benefit) [Table Text Block] </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/verboseLabel" xlink:label="us-gaap_ScheduleOfComponentsOfIncomeTaxExpenseBenefitTableTextBlock_lbl" xml:lang="en-US"> Schedule of Components of Income Tax Expense (Benefit) </label>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ScheduleOfEffectiveIncomeTaxRateReconciliationTableTextBlock" xlink:label="us-gaap_ScheduleOfEffectiveIncomeTaxRateReconciliationTableTextBlock"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_ScheduleOfEffectiveIncomeTaxRateReconciliationTableTextBlock" xlink:to="us-gaap_ScheduleOfEffectiveIncomeTaxRateReconciliationTableTextBlock_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_ScheduleOfEffectiveIncomeTaxRateReconciliationTableTextBlock_lbl" xml:lang="en-US"> Schedule of Effective Income Tax Rate Reconciliation [Table Text Block] </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/verboseLabel" xlink:label="us-gaap_ScheduleOfEffectiveIncomeTaxRateReconciliationTableTextBlock_lbl" xml:lang="en-US"> Schedule of Effective Income Tax Rate Reconciliation </label>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ScheduleOfDeferredTaxAssetsAndLiabilitiesTableTextBlock" xlink:label="us-gaap_ScheduleOfDeferredTaxAssetsAndLiabilitiesTableTextBlock"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_ScheduleOfDeferredTaxAssetsAndLiabilitiesTableTextBlock" xlink:to="us-gaap_ScheduleOfDeferredTaxAssetsAndLiabilitiesTableTextBlock_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_ScheduleOfDeferredTaxAssetsAndLiabilitiesTableTextBlock_lbl" xml:lang="en-US"> Schedule of Deferred Tax Assets and Liabilities [Table Text Block] </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/verboseLabel" xlink:label="us-gaap_ScheduleOfDeferredTaxAssetsAndLiabilitiesTableTextBlock_lbl" xml:lang="en-US"> Schedule of Deferred Tax Assets and Liabilities </label>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ScheduleOfIndefiniteLivedIntangibleAssetsTableTextBlock" xlink:label="us-gaap_ScheduleOfIndefiniteLivedIntangibleAssetsTableTextBlock"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_ScheduleOfIndefiniteLivedIntangibleAssetsTableTextBlock" xlink:to="us-gaap_ScheduleOfIndefiniteLivedIntangibleAssetsTableTextBlock_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_ScheduleOfIndefiniteLivedIntangibleAssetsTableTextBlock_lbl" xml:lang="en-US"> Schedule of Indefinite-Lived Intangible Assets [Table Text Block] </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_ScheduleOfIndefiniteLivedIntangibleAssetsTableTextBlock_lbl" xml:lang="en-US"> Schedule of company's other intangible assets </label>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ScheduleOfDebtTableTextBlock" xlink:label="us-gaap_ScheduleOfDebtTableTextBlock"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_ScheduleOfDebtTableTextBlock" xlink:to="us-gaap_ScheduleOfDebtTableTextBlock_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_ScheduleOfDebtTableTextBlock_lbl" xml:lang="en-US"> Schedule of Debt [Table Text Block] </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/verboseLabel" xlink:label="us-gaap_ScheduleOfDebtTableTextBlock_lbl" xml:lang="en-US"> Schedule of short-term and long-term debt </label>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ScheduleOfMaturitiesOfLongTermDebtTableTextBlock" xlink:label="us-gaap_ScheduleOfMaturitiesOfLongTermDebtTableTextBlock"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_ScheduleOfMaturitiesOfLongTermDebtTableTextBlock" xlink:to="us-gaap_ScheduleOfMaturitiesOfLongTermDebtTableTextBlock_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_ScheduleOfMaturitiesOfLongTermDebtTableTextBlock_lbl" xml:lang="en-US"> Schedule of Maturities of Long-term Debt [Table Text Block] </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_ScheduleOfMaturitiesOfLongTermDebtTableTextBlock_lbl" xml:lang="en-US"> Schedule of maturities of long-term debt and capital lease obligations </label>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ScheduleOfRentExpenseTableTextBlock" xlink:label="us-gaap_ScheduleOfRentExpenseTableTextBlock"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_ScheduleOfRentExpenseTableTextBlock" xlink:to="us-gaap_ScheduleOfRentExpenseTableTextBlock_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_ScheduleOfRentExpenseTableTextBlock_lbl" xml:lang="en-US"> Schedule of Rent Expense [Table Text Block] </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_ScheduleOfRentExpenseTableTextBlock_lbl" xml:lang="en-US"> Schedule of rent expense </label>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ScheduleOfShareBasedPaymentAwardStockOptionsValuationAssumptionsTableTextBlock" xlink:label="us-gaap_ScheduleOfShareBasedPaymentAwardStockOptionsValuationAssumptionsTableTextBlock"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_ScheduleOfShareBasedPaymentAwardStockOptionsValuationAssumptionsTableTextBlock" xlink:to="us-gaap_ScheduleOfShareBasedPaymentAwardStockOptionsValuationAssumptionsTableTextBlock_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_ScheduleOfShareBasedPaymentAwardStockOptionsValuationAssumptionsTableTextBlock_lbl" xml:lang="en-US"> Schedule of Share-based Payment Award, Stock Options, Valuation Assumptions [Table Text Block] </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/verboseLabel" xlink:label="us-gaap_ScheduleOfShareBasedPaymentAwardStockOptionsValuationAssumptionsTableTextBlock_lbl" xml:lang="en-US"> Schedule of weighted-average assumptions used in determining fair value of share based awards </label>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ScheduleOfShareBasedCompensationStockOptionsActivityTableTextBlock" xlink:label="us-gaap_ScheduleOfShareBasedCompensationStockOptionsActivityTableTextBlock"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_ScheduleOfShareBasedCompensationStockOptionsActivityTableTextBlock" xlink:to="us-gaap_ScheduleOfShareBasedCompensationStockOptionsActivityTableTextBlock_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_ScheduleOfShareBasedCompensationStockOptionsActivityTableTextBlock_lbl" xml:lang="en-US"> Schedule Of Share Based Compensation Stock Options Activity Table [Text Block] </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/verboseLabel" xlink:label="us-gaap_ScheduleOfShareBasedCompensationStockOptionsActivityTableTextBlock_lbl" xml:lang="en-US"> Schedule of company's stock option plan </label>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ScheduleOfShareBasedCompensationActivityTableTextBlock" xlink:label="us-gaap_ScheduleOfShareBasedCompensationActivityTableTextBlock"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_ScheduleOfShareBasedCompensationActivityTableTextBlock" xlink:to="us-gaap_ScheduleOfShareBasedCompensationActivityTableTextBlock_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_ScheduleOfShareBasedCompensationActivityTableTextBlock_lbl" xml:lang="en-US"> Schedule Of Share Based Compensation Activity Table [Text Block] </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/verboseLabel" xlink:label="us-gaap_ScheduleOfShareBasedCompensationActivityTableTextBlock_lbl" xml:lang="en-US"> Schedule of weighted average contractual life and exercise price </label>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ScheduleOfShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodGrantDateIntrinsicValueTableTextBlock" xlink:label="us-gaap_ScheduleOfShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodGrantDateIntrinsicValueTableTextBlock"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_ScheduleOfShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodGrantDateIntrinsicValueTableTextBlock" xlink:to="us-gaap_ScheduleOfShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodGrantDateIntrinsicValueTableTextBlock_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_ScheduleOfShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodGrantDateIntrinsicValueTableTextBlock_lbl" xml:lang="en-US"> Schedule of Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period, Grant Date Intrinsic Value [Table Text Block] </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/verboseLabel" xlink:label="us-gaap_ScheduleOfShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodGrantDateIntrinsicValueTableTextBlock_lbl" xml:lang="en-US"> Schedule of intrinsic value </label>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ReconciliationOfRevenueFromSegmentsToConsolidatedTable" xlink:label="us-gaap_ReconciliationOfRevenueFromSegmentsToConsolidatedTable"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_ReconciliationOfRevenueFromSegmentsToConsolidatedTable" xlink:to="us-gaap_ReconciliationOfRevenueFromSegmentsToConsolidatedTable_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_ReconciliationOfRevenueFromSegmentsToConsolidatedTable_lbl" xml:lang="en-US"> Reconciliation of Revenue from Segments to Consolidated [Table] </label>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/srt/2020/elts/srt-2020-01-31.xsd#srt_ProductOrServiceAxis" xlink:label="srt_ProductOrServiceAxis"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="srt_ProductOrServiceAxis" xlink:to="srt_ProductOrServiceAxis_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="srt_ProductOrServiceAxis_lbl" xml:lang="en-US"> Product and Service [Axis] </label>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/srt/2020/elts/srt-2020-01-31.xsd#srt_ProductsAndServicesDomain" xlink:label="srt_ProductsAndServicesDomain"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="srt_ProductsAndServicesDomain" xlink:to="srt_ProductsAndServicesDomain_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="srt_ProductsAndServicesDomain_lbl" xml:lang="en-US"> Products And Services [Domain] </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="srt_ProductsAndServicesDomain_lbl" xml:lang="en-US"> Product and Service [Domain] </label>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ProductMember" xlink:label="us-gaap_ProductMember"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_ProductMember" xlink:to="us-gaap_ProductMember_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_ProductMember_lbl" xml:lang="en-US"> Product [Member] </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_ProductMember_lbl" xml:lang="en-US"> Product [Member] </label>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ServiceMember" xlink:label="us-gaap_ServiceMember"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_ServiceMember" xlink:to="us-gaap_ServiceMember_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_ServiceMember_lbl" xml:lang="en-US"> Service [Member] </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_ServiceMember_lbl" xml:lang="en-US"> Refrigerant Side Services [Member] </label>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_SegmentReportingRevenueReconcilingItemLineItems" xlink:label="us-gaap_SegmentReportingRevenueReconcilingItemLineItems"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_SegmentReportingRevenueReconcilingItemLineItems" xlink:to="us-gaap_SegmentReportingRevenueReconcilingItemLineItems_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_SegmentReportingRevenueReconcilingItemLineItems_lbl" xml:lang="en-US"> Segment Reporting Revenue Reconciling Item [Line Items] </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_SegmentReportingRevenueReconcilingItemLineItems_lbl" xml:lang="en-US"> Segment Reporting, Revenue Reconciling Item [Line Items] </label>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_RevenueFromContractWithCustomerIncludingAssessedTax" xlink:label="us-gaap_RevenueFromContractWithCustomerIncludingAssessedTax"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_RevenueFromContractWithCustomerIncludingAssessedTax" xlink:to="us-gaap_RevenueFromContractWithCustomerIncludingAssessedTax_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_RevenueFromContractWithCustomerIncludingAssessedTax_lbl" xml:lang="en-US"> Revenue from Contract with Customer, Including Assessed Tax </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_RevenueFromContractWithCustomerIncludingAssessedTax_lbl" xml:lang="en-US"> Total </label>
<loc xlink:type="locator" xlink:href="hdsn-20201231.xsd#hdsn_SignificantAccountingPoliciesTable" xlink:label="hdsn_SignificantAccountingPoliciesTable"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="hdsn_SignificantAccountingPoliciesTable" xlink:to="hdsn_SignificantAccountingPoliciesTable_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:label="hdsn_SignificantAccountingPoliciesTable_lbl" xml:lang="en-US"> Significant Accounting Policies [Table] </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="hdsn_SignificantAccountingPoliciesTable_lbl" xml:lang="en-US"> Significant Accounting Policies [Table] </label>
<loc xlink:type="locator" xlink:href="hdsn-20201231.xsd#hdsn_SignificantAccountingPoliciesLineItems" xlink:label="hdsn_SignificantAccountingPoliciesLineItems"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="hdsn_SignificantAccountingPoliciesLineItems" xlink:to="hdsn_SignificantAccountingPoliciesLineItems_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:label="hdsn_SignificantAccountingPoliciesLineItems_lbl" xml:lang="en-US"> Significant Accounting Policies [Line Items] </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="hdsn_SignificantAccountingPoliciesLineItems_lbl" xml:lang="en-US"> Significant Accounting Policies [Line Items] </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="hdsn_SignificantAccountingPoliciesLineItems_lbl" xml:lang="en-US"> Significant Accounting Policies [Line Items] </label>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_NumberOfReportableSegments" xlink:label="us-gaap_NumberOfReportableSegments"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_NumberOfReportableSegments" xlink:to="us-gaap_NumberOfReportableSegments_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_NumberOfReportableSegments_lbl" xml:lang="en-US"> Number of Reportable Segments </label>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ConcentrationRiskPercentage1" xlink:label="us-gaap_ConcentrationRiskPercentage1"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_ConcentrationRiskPercentage1" xlink:to="us-gaap_ConcentrationRiskPercentage1_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_ConcentrationRiskPercentage1_lbl" xml:lang="en-US"> Concentration Risk, Percentage </label>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_AccountsReceivableNet" xlink:label="us-gaap_AccountsReceivableNet"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_AccountsReceivableNet" xlink:to="us-gaap_AccountsReceivableNet_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_AccountsReceivableNet_lbl" xml:lang="en-US"> Accounts Receivable, Net </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_AccountsReceivableNet_lbl" xml:lang="en-US"> Accounts Receivable, net </label>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_GoodwillImpairmentLoss" xlink:label="us-gaap_GoodwillImpairmentLoss"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_GoodwillImpairmentLoss" xlink:to="us-gaap_GoodwillImpairmentLoss_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_GoodwillImpairmentLoss_lbl" xml:lang="en-US"> Goodwill, Impairment Loss </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_GoodwillImpairmentLoss_lbl" xml:lang="en-US"> Goodwill impairment loss </label>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_OperatingLeaseLiability" xlink:label="us-gaap_OperatingLeaseLiability"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_OperatingLeaseLiability" xlink:to="us-gaap_OperatingLeaseLiability_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_OperatingLeaseLiability_lbl" xml:lang="en-US"> Operating Lease, Liability </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_OperatingLeaseLiability_lbl" xml:lang="en-US"> Present value of operating lease liabilities </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/verboseLabel" xlink:label="us-gaap_OperatingLeaseLiability_lbl" xml:lang="en-US"> Total operating lease liabilities </label>
<loc xlink:type="locator" xlink:href="hdsn-20201231.xsd#hdsn_CylinderDepositValue" xlink:label="hdsn_CylinderDepositValue"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="hdsn_CylinderDepositValue" xlink:to="hdsn_CylinderDepositValue_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:label="hdsn_CylinderDepositValue_lbl" xml:lang="en-US"> Amount of cylinder deposit value. </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="hdsn_CylinderDepositValue_lbl" xml:lang="en-US"> Cylinder Deposit Value </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="hdsn_CylinderDepositValue_lbl" xml:lang="en-US"> Cylinder deposit liability </label>
<loc xlink:type="locator" xlink:href="hdsn-20201231.xsd#hdsn_ContractTerm" xlink:label="hdsn_ContractTerm"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="hdsn_ContractTerm" xlink:to="hdsn_ContractTerm_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:label="hdsn_ContractTerm_lbl" xml:lang="en-US"> The length in years of a contract awarded to the company. </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="hdsn_ContractTerm_lbl" xml:lang="en-US"> Contract Term </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="hdsn_ContractTerm_lbl" xml:lang="en-US"> Contract term </label>
<loc xlink:type="locator" xlink:href="hdsn-20201231.xsd#hdsn_ContractRenewalTerm" xlink:label="hdsn_ContractRenewalTerm"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="hdsn_ContractRenewalTerm" xlink:to="hdsn_ContractRenewalTerm_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:label="hdsn_ContractRenewalTerm_lbl" xml:lang="en-US"> The length in years of the contract renewal. </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="hdsn_ContractRenewalTerm_lbl" xml:lang="en-US"> Contract Renewal Term </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="hdsn_ContractRenewalTerm_lbl" xml:lang="en-US"> Contract renewal term </label>
<loc xlink:type="locator" xlink:href="hdsn-20201231.xsd#hdsn_PercentageOfTaxableIncomeThatAreOffsetAgainstNetOperatingLossCarryoversAndCarryback" xlink:label="hdsn_PercentageOfTaxableIncomeThatAreOffsetAgainstNetOperatingLossCarryoversAndCarryback"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="hdsn_PercentageOfTaxableIncomeThatAreOffsetAgainstNetOperatingLossCarryoversAndCarryback" xlink:to="hdsn_PercentageOfTaxableIncomeThatAreOffsetAgainstNetOperatingLossCarryoversAndCarryback_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:label="hdsn_PercentageOfTaxableIncomeThatAreOffsetAgainstNetOperatingLossCarryoversAndCarryback_lbl" xml:lang="en-US"> Represents the percentage of taxable income that are offset against NOL carryovers and carrybacks. </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="hdsn_PercentageOfTaxableIncomeThatAreOffsetAgainstNetOperatingLossCarryoversAndCarryback_lbl" xml:lang="en-US"> Percentage of Taxable Income that are Offset Against Net Operating Loss Carryovers and Carryback </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="hdsn_PercentageOfTaxableIncomeThatAreOffsetAgainstNetOperatingLossCarryoversAndCarryback_lbl" xml:lang="en-US"> Percent of taxable income offset for taxable years beginning before 2021 </label>
<loc xlink:type="locator" xlink:href="hdsn-20201231.xsd#hdsn_TaxCutsAndJobsActPreliminaryIncomeTaxExpenseBenefitRelatedToAlternativeMinimumTaxRefund" xlink:label="hdsn_TaxCutsAndJobsActPreliminaryIncomeTaxExpenseBenefitRelatedToAlternativeMinimumTaxRefund"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="hdsn_TaxCutsAndJobsActPreliminaryIncomeTaxExpenseBenefitRelatedToAlternativeMinimumTaxRefund" xlink:to="hdsn_TaxCutsAndJobsActPreliminaryIncomeTaxExpenseBenefitRelatedToAlternativeMinimumTaxRefund_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:label="hdsn_TaxCutsAndJobsActPreliminaryIncomeTaxExpenseBenefitRelatedToAlternativeMinimumTaxRefund_lbl" xml:lang="en-US"> Amount of preliminary income tax expense (benefit) related to alternate minimum tax from effect of Tax Cuts and Jobs Act. </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="hdsn_TaxCutsAndJobsActPreliminaryIncomeTaxExpenseBenefitRelatedToAlternativeMinimumTaxRefund_lbl" xml:lang="en-US"> Tax Cuts and Jobs Act, Preliminary Income Tax Expense (Benefit) Related to Alternative Minimum Tax Refund </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2009/role/negatedLabel" xlink:label="hdsn_TaxCutsAndJobsActPreliminaryIncomeTaxExpenseBenefitRelatedToAlternativeMinimumTaxRefund_lbl" xml:lang="en-US"> Preliminary tax benefit related to the alternative minimum tax refund </label>
<loc xlink:type="locator" xlink:href="hdsn-20201231.xsd#hdsn_TaxCutsAndJobsActAdditionalIncomeTaxExpenseBenefitRelatedToAlternativeMinimumTaxRefund" xlink:label="hdsn_TaxCutsAndJobsActAdditionalIncomeTaxExpenseBenefitRelatedToAlternativeMinimumTaxRefund"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="hdsn_TaxCutsAndJobsActAdditionalIncomeTaxExpenseBenefitRelatedToAlternativeMinimumTaxRefund" xlink:to="hdsn_TaxCutsAndJobsActAdditionalIncomeTaxExpenseBenefitRelatedToAlternativeMinimumTaxRefund_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:label="hdsn_TaxCutsAndJobsActAdditionalIncomeTaxExpenseBenefitRelatedToAlternativeMinimumTaxRefund_lbl" xml:lang="en-US"> Amount of additional income tax expense (benefit) related to alternate minimum tax from effect of Tax Cuts and Jobs Act. </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="hdsn_TaxCutsAndJobsActAdditionalIncomeTaxExpenseBenefitRelatedToAlternativeMinimumTaxRefund_lbl" xml:lang="en-US"> Tax Cuts And Jobs Act Additional Income Tax Expense Benefit Related To Alternative Minimum Tax Refund </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="hdsn_TaxCutsAndJobsActAdditionalIncomeTaxExpenseBenefitRelatedToAlternativeMinimumTaxRefund_lbl" xml:lang="en-US"> Additional tax benefit related to the alternative minimum tax refund </label>
<loc xlink:type="locator" xlink:href="hdsn-20201231.xsd#hdsn_PercentageOfAdjustedTaxableIncomeThroughModificationsToSections163J" xlink:label="hdsn_PercentageOfAdjustedTaxableIncomeThroughModificationsToSections163J"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="hdsn_PercentageOfAdjustedTaxableIncomeThroughModificationsToSections163J" xlink:to="hdsn_PercentageOfAdjustedTaxableIncomeThroughModificationsToSections163J_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:label="hdsn_PercentageOfAdjustedTaxableIncomeThroughModificationsToSections163J_lbl" xml:lang="en-US"> Percent of adjusted taxable income. </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="hdsn_PercentageOfAdjustedTaxableIncomeThroughModificationsToSections163J_lbl" xml:lang="en-US"> Percentage of Adjusted Taxable Income through Modifications to Sections 163(j) </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="hdsn_PercentageOfAdjustedTaxableIncomeThroughModificationsToSections163J_lbl" xml:lang="en-US"> Percent of adjusted taxable income </label>
<loc xlink:type="locator" xlink:href="hdsn-20201231.xsd#hdsn_IncreaseDecreaseInInterestExpenseThroughModificationsToSection163J" xlink:label="hdsn_IncreaseDecreaseInInterestExpenseThroughModificationsToSection163J"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="hdsn_IncreaseDecreaseInInterestExpenseThroughModificationsToSection163J" xlink:to="hdsn_IncreaseDecreaseInInterestExpenseThroughModificationsToSection163J_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:label="hdsn_IncreaseDecreaseInInterestExpenseThroughModificationsToSection163J_lbl" xml:lang="en-US"> Increase in allowable interest expense through the modifications to Section 163(j). </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="hdsn_IncreaseDecreaseInInterestExpenseThroughModificationsToSection163J_lbl" xml:lang="en-US"> Increase (Decrease) in Interest Expense through Modifications to Section 163(j) </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="hdsn_IncreaseDecreaseInInterestExpenseThroughModificationsToSection163J_lbl" xml:lang="en-US"> Increase in allowable interest expense </label>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_OperatingLossCarryforwards" xlink:label="us-gaap_OperatingLossCarryforwards"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_OperatingLossCarryforwards" xlink:to="us-gaap_OperatingLossCarryforwards_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_OperatingLossCarryforwards_lbl" xml:lang="en-US"> Operating Loss Carryforwards </label>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DeferredTaxAssetsValuationAllowance" xlink:label="us-gaap_DeferredTaxAssetsValuationAllowance"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_DeferredTaxAssetsValuationAllowance" xlink:to="us-gaap_DeferredTaxAssetsValuationAllowance_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_DeferredTaxAssetsValuationAllowance_lbl" xml:lang="en-US"> Deferred Tax Assets, Valuation Allowance </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2009/role/negatedLabel" xlink:label="us-gaap_DeferredTaxAssetsValuationAllowance_lbl" xml:lang="en-US"> - Valuation allowance </label>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ValuationAllowanceDeferredTaxAssetChangeInAmount" xlink:label="us-gaap_ValuationAllowanceDeferredTaxAssetChangeInAmount"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_ValuationAllowanceDeferredTaxAssetChangeInAmount" xlink:to="us-gaap_ValuationAllowanceDeferredTaxAssetChangeInAmount_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_ValuationAllowanceDeferredTaxAssetChangeInAmount_lbl" xml:lang="en-US"> Valuation Allowance, Deferred Tax Asset, Increase (Decrease), Amount </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_ValuationAllowanceDeferredTaxAssetChangeInAmount_lbl" xml:lang="en-US"> Valuation Allowance, Deferred Tax Asset, Increase (Decrease), Amount </label>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount" xlink:label="us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount" xlink:to="us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount_lbl" xml:lang="en-US"> Antidilutive Securities Excluded From Computation Of Earnings Per Share Amount </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount_lbl" xml:lang="en-US"> Options and warrants excluded from the calculation of diluted shares </label>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_AccountsNotesAndLoansReceivableLineItems" xlink:label="us-gaap_AccountsNotesAndLoansReceivableLineItems"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_AccountsNotesAndLoansReceivableLineItems" xlink:to="us-gaap_AccountsNotesAndLoansReceivableLineItems_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_AccountsNotesAndLoansReceivableLineItems_lbl" xml:lang="en-US"> Accounts, Notes, Loans and Financing Receivable [Line Items] </label>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_AllowanceForDoubtfulAccountsReceivable" xlink:label="us-gaap_AllowanceForDoubtfulAccountsReceivable"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_AllowanceForDoubtfulAccountsReceivable" xlink:to="us-gaap_AllowanceForDoubtfulAccountsReceivable_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_AllowanceForDoubtfulAccountsReceivable_lbl" xml:lang="en-US"> Allowance for Doubtful Accounts Receivable </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/periodEndLabel" xlink:label="us-gaap_AllowanceForDoubtfulAccountsReceivable_lbl" xml:lang="en-US"> Ending Balance </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/periodStartLabel" xlink:label="us-gaap_AllowanceForDoubtfulAccountsReceivable_lbl" xml:lang="en-US"> Beginning Balance </label>
<loc xlink:type="locator" xlink:href="hdsn-20201231.xsd#hdsn_AllowanceForDoubtfulAccountsReceivableDeductionsAndOther" xlink:label="hdsn_AllowanceForDoubtfulAccountsReceivableDeductionsAndOther"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="hdsn_AllowanceForDoubtfulAccountsReceivableDeductionsAndOther" xlink:to="hdsn_AllowanceForDoubtfulAccountsReceivableDeductionsAndOther_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:label="hdsn_AllowanceForDoubtfulAccountsReceivableDeductionsAndOther_lbl" xml:lang="en-US"> Amount of deductions and other in the allowance for doubtful accounts. </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="hdsn_AllowanceForDoubtfulAccountsReceivableDeductionsAndOther_lbl" xml:lang="en-US"> Allowance For Doubtful Accounts Receivable Deductions And Other </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/verboseLabel" xlink:label="hdsn_AllowanceForDoubtfulAccountsReceivableDeductionsAndOther_lbl" xml:lang="en-US"> Deductions and Other </label>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_AllowanceForDoubtfulAccountsReceivableCurrent" xlink:label="us-gaap_AllowanceForDoubtfulAccountsReceivableCurrent"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_AllowanceForDoubtfulAccountsReceivableCurrent" xlink:to="us-gaap_AllowanceForDoubtfulAccountsReceivableCurrent_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_AllowanceForDoubtfulAccountsReceivableCurrent_lbl" xml:lang="en-US"> Allowance for Doubtful Accounts Receivable, Current </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/verboseLabel" xlink:label="us-gaap_AllowanceForDoubtfulAccountsReceivableCurrent_lbl" xml:lang="en-US"> Trade accounts receivable are net of reserves for doubtful accounts </label>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_InventoryCurrentTable" xlink:label="us-gaap_InventoryCurrentTable"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_InventoryCurrentTable" xlink:to="us-gaap_InventoryCurrentTable_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_InventoryCurrentTable_lbl" xml:lang="en-US"> Inventory, Current [Table] </label>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_InventoryLineItems" xlink:label="us-gaap_InventoryLineItems"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_InventoryLineItems" xlink:to="us-gaap_InventoryLineItems_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_InventoryLineItems_lbl" xml:lang="en-US"> Inventory [Line Items] </label>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_InventoryGross" xlink:label="us-gaap_InventoryGross"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_InventoryGross" xlink:to="us-gaap_InventoryGross_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_InventoryGross_lbl" xml:lang="en-US"> Inventory, Gross </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/verboseLabel" xlink:label="us-gaap_InventoryGross_lbl" xml:lang="en-US"> Refrigerants and cylinders </label>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_InventoryAdjustments" xlink:label="us-gaap_InventoryAdjustments"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_InventoryAdjustments" xlink:to="us-gaap_InventoryAdjustments_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_InventoryAdjustments_lbl" xml:lang="en-US"> Inventory Adjustments </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2009/role/negatedLabel" xlink:label="us-gaap_InventoryAdjustments_lbl" xml:lang="en-US"> Less: net realizable value adjustments </label>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ScheduleOfPropertyPlantAndEquipmentTable" xlink:label="us-gaap_ScheduleOfPropertyPlantAndEquipmentTable"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_ScheduleOfPropertyPlantAndEquipmentTable" xlink:to="us-gaap_ScheduleOfPropertyPlantAndEquipmentTable_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_ScheduleOfPropertyPlantAndEquipmentTable_lbl" xml:lang="en-US"> Property, Plant and Equipment [Table] </label>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_PropertyPlantAndEquipmentByTypeAxis" xlink:label="us-gaap_PropertyPlantAndEquipmentByTypeAxis"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_PropertyPlantAndEquipmentByTypeAxis" xlink:to="us-gaap_PropertyPlantAndEquipmentByTypeAxis_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_PropertyPlantAndEquipmentByTypeAxis_lbl" xml:lang="en-US"> Property, Plant and Equipment, Type [Axis] </label>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_PropertyPlantAndEquipmentTypeDomain" xlink:label="us-gaap_PropertyPlantAndEquipmentTypeDomain"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_PropertyPlantAndEquipmentTypeDomain" xlink:to="us-gaap_PropertyPlantAndEquipmentTypeDomain_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_PropertyPlantAndEquipmentTypeDomain_lbl" xml:lang="en-US"> Property Plant And Equipment Type [Domain] </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_PropertyPlantAndEquipmentTypeDomain_lbl" xml:lang="en-US"> Property, Plant and Equipment, Type [Domain] </label>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_LandMember" xlink:label="us-gaap_LandMember"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_LandMember" xlink:to="us-gaap_LandMember_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_LandMember_lbl" xml:lang="en-US"> Land [Member] </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_LandMember_lbl" xml:lang="en-US"> Land </label>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_LandImprovementsMember" xlink:label="us-gaap_LandImprovementsMember"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_LandImprovementsMember" xlink:to="us-gaap_LandImprovementsMember_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_LandImprovementsMember_lbl" xml:lang="en-US"> Land Improvements [Member] </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_LandImprovementsMember_lbl" xml:lang="en-US"> Land improvements </label>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_BuildingMember" xlink:label="us-gaap_BuildingMember"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_BuildingMember" xlink:to="us-gaap_BuildingMember_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_BuildingMember_lbl" xml:lang="en-US"> Building [Member] </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_BuildingMember_lbl" xml:lang="en-US"> Buildings </label>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_BuildingImprovementsMember" xlink:label="us-gaap_BuildingImprovementsMember"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_BuildingImprovementsMember" xlink:to="us-gaap_BuildingImprovementsMember_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_BuildingImprovementsMember_lbl" xml:lang="en-US"> Building Improvements [Member] </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_BuildingImprovementsMember_lbl" xml:lang="en-US"> Building improvements </label>
<loc xlink:type="locator" xlink:href="hdsn-20201231.xsd#hdsn_CylindersMember" xlink:label="hdsn_CylindersMember"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="hdsn_CylindersMember" xlink:to="hdsn_CylindersMember_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="hdsn_CylindersMember_lbl" xml:lang="en-US"> Cylinders [Member] </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="hdsn_CylindersMember_lbl" xml:lang="en-US"> Cylinders </label>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_EquipmentMember" xlink:label="us-gaap_EquipmentMember"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_EquipmentMember" xlink:to="us-gaap_EquipmentMember_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_EquipmentMember_lbl" xml:lang="en-US"> Equipment [Member] </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_EquipmentMember_lbl" xml:lang="en-US"> Equipment </label>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_AssetsHeldUnderCapitalLeasesMember" xlink:label="us-gaap_AssetsHeldUnderCapitalLeasesMember"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_AssetsHeldUnderCapitalLeasesMember" xlink:to="us-gaap_AssetsHeldUnderCapitalLeasesMember_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_AssetsHeldUnderCapitalLeasesMember_lbl" xml:lang="en-US"> Assets Held Under Capital Leases [Member] </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_AssetsHeldUnderCapitalLeasesMember_lbl" xml:lang="en-US"> Equipment under capital lease </label>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_VehiclesMember" xlink:label="us-gaap_VehiclesMember"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_VehiclesMember" xlink:to="us-gaap_VehiclesMember_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_VehiclesMember_lbl" xml:lang="en-US"> Vehicles [Member] </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_VehiclesMember_lbl" xml:lang="en-US"> Vehicles </label>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ComputerEquipmentMember" xlink:label="us-gaap_ComputerEquipmentMember"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_ComputerEquipmentMember" xlink:to="us-gaap_ComputerEquipmentMember_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_ComputerEquipmentMember_lbl" xml:lang="en-US"> Computer Equipment [Member] </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_ComputerEquipmentMember_lbl" xml:lang="en-US"> Lab and computer equipment, software </label>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_FurnitureAndFixturesMember" xlink:label="us-gaap_FurnitureAndFixturesMember"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_FurnitureAndFixturesMember" xlink:to="us-gaap_FurnitureAndFixturesMember_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_FurnitureAndFixturesMember_lbl" xml:lang="en-US"> Furniture And Fixtures [Member] </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_FurnitureAndFixturesMember_lbl" xml:lang="en-US"> Furniture & fixtures </label>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_LeaseholdImprovementsMember" xlink:label="us-gaap_LeaseholdImprovementsMember"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_LeaseholdImprovementsMember" xlink:to="us-gaap_LeaseholdImprovementsMember_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_LeaseholdImprovementsMember_lbl" xml:lang="en-US"> Leasehold Improvements [Member] </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_LeaseholdImprovementsMember_lbl" xml:lang="en-US"> Leasehold improvements </label>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_AssetUnderConstructionMember" xlink:label="us-gaap_AssetUnderConstructionMember"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_AssetUnderConstructionMember" xlink:to="us-gaap_AssetUnderConstructionMember_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_AssetUnderConstructionMember_lbl" xml:lang="en-US"> Asset Under Construction [Member] </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_AssetUnderConstructionMember_lbl" xml:lang="en-US"> Equipment under construction </label>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/srt/2020/elts/srt-2020-01-31.xsd#srt_RangeAxis" xlink:label="srt_RangeAxis"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="srt_RangeAxis" xlink:to="srt_RangeAxis_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="srt_RangeAxis_lbl" xml:lang="en-US"> Range [Axis] </label>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/srt/2020/elts/srt-2020-01-31.xsd#srt_RangeMember" xlink:label="srt_RangeMember"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="srt_RangeMember" xlink:to="srt_RangeMember_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="srt_RangeMember_lbl" xml:lang="en-US"> Range [Member] </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="srt_RangeMember_lbl" xml:lang="en-US"> Range [Domain] </label>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/srt/2020/elts/srt-2020-01-31.xsd#srt_MinimumMember" xlink:label="srt_MinimumMember"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="srt_MinimumMember" xlink:to="srt_MinimumMember_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="srt_MinimumMember_lbl" xml:lang="en-US"> Minimum [Member] </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="srt_MinimumMember_lbl" xml:lang="en-US"> Minimum </label>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/srt/2020/elts/srt-2020-01-31.xsd#srt_MaximumMember" xlink:label="srt_MaximumMember"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="srt_MaximumMember" xlink:to="srt_MaximumMember_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="srt_MaximumMember_lbl" xml:lang="en-US"> Maximum [Member] </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="srt_MaximumMember_lbl" xml:lang="en-US"> Maximum </label>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_PropertyPlantAndEquipmentLineItems" xlink:label="us-gaap_PropertyPlantAndEquipmentLineItems"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_PropertyPlantAndEquipmentLineItems" xlink:to="us-gaap_PropertyPlantAndEquipmentLineItems_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_PropertyPlantAndEquipmentLineItems_lbl" xml:lang="en-US"> Property, Plant and Equipment [Line Items] </label>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_PropertyPlantAndEquipmentGross" xlink:label="us-gaap_PropertyPlantAndEquipmentGross"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_PropertyPlantAndEquipmentGross" xlink:to="us-gaap_PropertyPlantAndEquipmentGross_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_PropertyPlantAndEquipmentGross_lbl" xml:lang="en-US"> Property, Plant and Equipment, Gross </label>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment" xlink:label="us-gaap_AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment" xlink:to="us-gaap_AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment_lbl" xml:lang="en-US"> Accumulated Depreciation, Depletion and Amortization, Property, Plant, and Equipment </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/verboseLabel" xlink:label="us-gaap_AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment_lbl" xml:lang="en-US"> Accumulated depreciation </label>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_PropertyPlantAndEquipmentUsefulLife" xlink:label="us-gaap_PropertyPlantAndEquipmentUsefulLife"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_PropertyPlantAndEquipmentUsefulLife" xlink:to="us-gaap_PropertyPlantAndEquipmentUsefulLife_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_PropertyPlantAndEquipmentUsefulLife_lbl" xml:lang="en-US"> Property, Plant and Equipment, Useful Life </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/verboseLabel" xlink:label="us-gaap_PropertyPlantAndEquipmentUsefulLife_lbl" xml:lang="en-US"> Property, Plant and Equipment, Useful Estimated Lives </label>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_Depreciation" xlink:label="us-gaap_Depreciation"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_Depreciation" xlink:to="us-gaap_Depreciation_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_Depreciation_lbl" xml:lang="en-US"> Depreciation </label>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_CostOfGoodsAndServicesSoldDepreciation" xlink:label="us-gaap_CostOfGoodsAndServicesSoldDepreciation"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_CostOfGoodsAndServicesSoldDepreciation" xlink:to="us-gaap_CostOfGoodsAndServicesSoldDepreciation_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_CostOfGoodsAndServicesSoldDepreciation_lbl" xml:lang="en-US"> Cost, Depreciation </label>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueNextTwelveMonths" xlink:label="us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueNextTwelveMonths"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueNextTwelveMonths" xlink:to="us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueNextTwelveMonths_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueNextTwelveMonths_lbl" xml:lang="en-US"> Lessee, Operating Lease, Liability, Payments, Due Next Twelve Months </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueNextTwelveMonths_lbl" xml:lang="en-US"> -2021 </label>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueYearTwo" xlink:label="us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueYearTwo"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueYearTwo" xlink:to="us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueYearTwo_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueYearTwo_lbl" xml:lang="en-US"> Lessee, Operating Lease, Liability, Payments, Due Year Two </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueYearTwo_lbl" xml:lang="en-US"> -2022 </label>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueYearThree" xlink:label="us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueYearThree"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueYearThree" xlink:to="us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueYearThree_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueYearThree_lbl" xml:lang="en-US"> Lessee, Operating Lease, Liability, Payments, Due Year Three </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueYearThree_lbl" xml:lang="en-US"> -2023 </label>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueYearFour" xlink:label="us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueYearFour"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueYearFour" xlink:to="us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueYearFour_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueYearFour_lbl" xml:lang="en-US"> Lessee, Operating Lease, Liability, Payments, Due Year Four </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/verboseLabel" xlink:label="us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueYearFour_lbl" xml:lang="en-US"> -2024 </label>
<loc xlink:type="locator" xlink:href="hdsn-20201231.xsd#hdsn_LesseeOperatingLeaseLiabilityPaymentsDueAfterYearFour" xlink:label="hdsn_LesseeOperatingLeaseLiabilityPaymentsDueAfterYearFour"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="hdsn_LesseeOperatingLeaseLiabilityPaymentsDueAfterYearFour" xlink:to="hdsn_LesseeOperatingLeaseLiabilityPaymentsDueAfterYearFour_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:label="hdsn_LesseeOperatingLeaseLiabilityPaymentsDueAfterYearFour_lbl" xml:lang="en-US"> Amount of lessee's undiscounted obligation for lease payments for operating lease, due after fourth fiscal year following latest fiscal year. </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="hdsn_LesseeOperatingLeaseLiabilityPaymentsDueAfterYearFour_lbl" xml:lang="en-US"> Lessee Operating Lease Liability Payments Due After Year Four </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="hdsn_LesseeOperatingLeaseLiabilityPaymentsDueAfterYearFour_lbl" xml:lang="en-US"> -Thereafter </label>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_LesseeOperatingLeaseLiabilityPaymentsDue" xlink:label="us-gaap_LesseeOperatingLeaseLiabilityPaymentsDue"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_LesseeOperatingLeaseLiabilityPaymentsDue" xlink:to="us-gaap_LesseeOperatingLeaseLiabilityPaymentsDue_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_LesseeOperatingLeaseLiabilityPaymentsDue_lbl" xml:lang="en-US"> Lessee, Operating Lease, Liability, Payments, Due </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/totalLabel" xlink:label="us-gaap_LesseeOperatingLeaseLiabilityPaymentsDue_lbl" xml:lang="en-US"> Total undiscounted operating lease payments </label>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_LesseeOperatingLeaseLiabilityUndiscountedExcessAmount" xlink:label="us-gaap_LesseeOperatingLeaseLiabilityUndiscountedExcessAmount"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_LesseeOperatingLeaseLiabilityUndiscountedExcessAmount" xlink:to="us-gaap_LesseeOperatingLeaseLiabilityUndiscountedExcessAmount_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_LesseeOperatingLeaseLiabilityUndiscountedExcessAmount_lbl" xml:lang="en-US"> Lessee, Operating Lease, Liability, Undiscounted Excess Amount </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2009/role/negatedLabel" xlink:label="us-gaap_LesseeOperatingLeaseLiabilityUndiscountedExcessAmount_lbl" xml:lang="en-US"> Less imputed interest </label>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_BalanceSheetLocationAxis" xlink:label="us-gaap_BalanceSheetLocationAxis"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_BalanceSheetLocationAxis" xlink:to="us-gaap_BalanceSheetLocationAxis_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_BalanceSheetLocationAxis_lbl" xml:lang="en-US"> Balance Sheet Location [Axis] </label>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_BalanceSheetLocationDomain" xlink:label="us-gaap_BalanceSheetLocationDomain"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_BalanceSheetLocationDomain" xlink:to="us-gaap_BalanceSheetLocationDomain_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_BalanceSheetLocationDomain_lbl" xml:lang="en-US"> Balance Sheet Location [Domain] </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_BalanceSheetLocationDomain_lbl" xml:lang="en-US"> Balance Sheet Location [Domain] </label>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_AccountsPayableAndAccruedLiabilitiesMember" xlink:label="us-gaap_AccountsPayableAndAccruedLiabilitiesMember"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_AccountsPayableAndAccruedLiabilitiesMember" xlink:to="us-gaap_AccountsPayableAndAccruedLiabilitiesMember_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_AccountsPayableAndAccruedLiabilitiesMember_lbl" xml:lang="en-US"> Accounts Payable And Accrued Liabilities [Member] </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_AccountsPayableAndAccruedLiabilitiesMember_lbl" xml:lang="en-US"> Accounts Payable and Accrued Liabilities [Member] </label>
<loc xlink:type="locator" xlink:href="hdsn-20201231.xsd#hdsn_BalanceSheetClassificationAbstract" xlink:label="hdsn_BalanceSheetClassificationAbstract"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="hdsn_BalanceSheetClassificationAbstract" xlink:to="hdsn_BalanceSheetClassificationAbstract_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="hdsn_BalanceSheetClassificationAbstract_lbl" xml:lang="en-US"> Balance Sheet Classification [Abstract] </label>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_OperatingLeaseLiabilityCurrent" xlink:label="us-gaap_OperatingLeaseLiabilityCurrent"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_OperatingLeaseLiabilityCurrent" xlink:to="us-gaap_OperatingLeaseLiabilityCurrent_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_OperatingLeaseLiabilityCurrent_lbl" xml:lang="en-US"> Operating Lease, Liability, Current </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/verboseLabel" xlink:label="us-gaap_OperatingLeaseLiabilityCurrent_lbl" xml:lang="en-US"> Current lease liabilities (recorded in Accrued expenses and other current liabilities) </label>
<loc xlink:type="locator" xlink:href="hdsn-20201231.xsd#hdsn_OtherInformationAbstract" xlink:label="hdsn_OtherInformationAbstract"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="hdsn_OtherInformationAbstract" xlink:to="hdsn_OtherInformationAbstract_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="hdsn_OtherInformationAbstract_lbl" xml:lang="en-US"> Other Information [Abstract] </label>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_OperatingLeaseWeightedAverageRemainingLeaseTerm1" xlink:label="us-gaap_OperatingLeaseWeightedAverageRemainingLeaseTerm1"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_OperatingLeaseWeightedAverageRemainingLeaseTerm1" xlink:to="us-gaap_OperatingLeaseWeightedAverageRemainingLeaseTerm1_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_OperatingLeaseWeightedAverageRemainingLeaseTerm1_lbl" xml:lang="en-US"> Operating Lease, Weighted Average Remaining Lease Term </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/verboseLabel" xlink:label="us-gaap_OperatingLeaseWeightedAverageRemainingLeaseTerm1_lbl" xml:lang="en-US"> Weighted-average remaining term for operating leases </label>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_OperatingLeaseWeightedAverageDiscountRatePercent" xlink:label="us-gaap_OperatingLeaseWeightedAverageDiscountRatePercent"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_OperatingLeaseWeightedAverageDiscountRatePercent" xlink:to="us-gaap_OperatingLeaseWeightedAverageDiscountRatePercent_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_OperatingLeaseWeightedAverageDiscountRatePercent_lbl" xml:lang="en-US"> Operating Lease, Weighted Average Discount Rate, Percent </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/verboseLabel" xlink:label="us-gaap_OperatingLeaseWeightedAverageDiscountRatePercent_lbl" xml:lang="en-US"> Weighted-average discount rate for operating leases </label>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_LesseeLeaseDescriptionTable" xlink:label="us-gaap_LesseeLeaseDescriptionTable"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_LesseeLeaseDescriptionTable" xlink:to="us-gaap_LesseeLeaseDescriptionTable_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_LesseeLeaseDescriptionTable_lbl" xml:lang="en-US"> Lessee, Lease, Description [Table] </label>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_LesseeLeaseDescriptionLineItems" xlink:label="us-gaap_LesseeLeaseDescriptionLineItems"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_LesseeLeaseDescriptionLineItems" xlink:to="us-gaap_LesseeLeaseDescriptionLineItems_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_LesseeLeaseDescriptionLineItems_lbl" xml:lang="en-US"> Lessee, Lease, Description [Line Items] </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_LesseeLeaseDescriptionLineItems_lbl" xml:lang="en-US"> Leases </label>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_LesseeOperatingLeaseTermOfContract" xlink:label="us-gaap_LesseeOperatingLeaseTermOfContract"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_LesseeOperatingLeaseTermOfContract" xlink:to="us-gaap_LesseeOperatingLeaseTermOfContract_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_LesseeOperatingLeaseTermOfContract_lbl" xml:lang="en-US"> Lessee, Operating Lease, Term of Contract </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_LesseeOperatingLeaseTermOfContract_lbl" xml:lang="en-US"> Lessee, Operating Lease, Term of Contract </label>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_OperatingLeaseExpense" xlink:label="us-gaap_OperatingLeaseExpense"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_OperatingLeaseExpense" xlink:to="us-gaap_OperatingLeaseExpense_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_OperatingLeaseExpense_lbl" xml:lang="en-US"> Operating Lease, Expense </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_OperatingLeaseExpense_lbl" xml:lang="en-US"> Operating lease expense </label>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_OperatingLeasePayments" xlink:label="us-gaap_OperatingLeasePayments"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_OperatingLeasePayments" xlink:to="us-gaap_OperatingLeasePayments_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_OperatingLeasePayments_lbl" xml:lang="en-US"> Operating Lease, Payments </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_OperatingLeasePayments_lbl" xml:lang="en-US"> operating lease liabilities </label>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_CurrentIncomeTaxExpenseBenefitContinuingOperationsAbstract" xlink:label="us-gaap_CurrentIncomeTaxExpenseBenefitContinuingOperationsAbstract"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_CurrentIncomeTaxExpenseBenefitContinuingOperationsAbstract" xlink:to="us-gaap_CurrentIncomeTaxExpenseBenefitContinuingOperationsAbstract_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_CurrentIncomeTaxExpenseBenefitContinuingOperationsAbstract_lbl" xml:lang="en-US"> Current Income Tax Expense (Benefit), Continuing Operations [Abstract] </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/verboseLabel" xlink:label="us-gaap_CurrentIncomeTaxExpenseBenefitContinuingOperationsAbstract_lbl" xml:lang="en-US"> Current: </label>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_CurrentFederalTaxExpenseBenefit" xlink:label="us-gaap_CurrentFederalTaxExpenseBenefit"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_CurrentFederalTaxExpenseBenefit" xlink:to="us-gaap_CurrentFederalTaxExpenseBenefit_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_CurrentFederalTaxExpenseBenefit_lbl" xml:lang="en-US"> Current Federal Tax Expense (Benefit) </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/verboseLabel" xlink:label="us-gaap_CurrentFederalTaxExpenseBenefit_lbl" xml:lang="en-US"> Federal </label>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_CurrentStateAndLocalTaxExpenseBenefit" xlink:label="us-gaap_CurrentStateAndLocalTaxExpenseBenefit"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_CurrentStateAndLocalTaxExpenseBenefit" xlink:to="us-gaap_CurrentStateAndLocalTaxExpenseBenefit_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_CurrentStateAndLocalTaxExpenseBenefit_lbl" xml:lang="en-US"> Current State and Local Tax Expense (Benefit) </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/verboseLabel" xlink:label="us-gaap_CurrentStateAndLocalTaxExpenseBenefit_lbl" xml:lang="en-US"> State and local </label>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_CurrentIncomeTaxExpenseBenefit" xlink:label="us-gaap_CurrentIncomeTaxExpenseBenefit"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_CurrentIncomeTaxExpenseBenefit" xlink:to="us-gaap_CurrentIncomeTaxExpenseBenefit_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_CurrentIncomeTaxExpenseBenefit_lbl" xml:lang="en-US"> Current Income Tax Expense (Benefit) </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/totalLabel" xlink:label="us-gaap_CurrentIncomeTaxExpenseBenefit_lbl" xml:lang="en-US"> Current Income Tax Expense (Benefit), Total </label>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DeferredIncomeTaxExpenseBenefitContinuingOperationsAbstract" xlink:label="us-gaap_DeferredIncomeTaxExpenseBenefitContinuingOperationsAbstract"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_DeferredIncomeTaxExpenseBenefitContinuingOperationsAbstract" xlink:to="us-gaap_DeferredIncomeTaxExpenseBenefitContinuingOperationsAbstract_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_DeferredIncomeTaxExpenseBenefitContinuingOperationsAbstract_lbl" xml:lang="en-US"> Deferred Income Tax Expense (Benefit), Continuing Operations [Abstract] </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/verboseLabel" xlink:label="us-gaap_DeferredIncomeTaxExpenseBenefitContinuingOperationsAbstract_lbl" xml:lang="en-US"> Deferred </label>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DeferredFederalIncomeTaxExpenseBenefit" xlink:label="us-gaap_DeferredFederalIncomeTaxExpenseBenefit"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_DeferredFederalIncomeTaxExpenseBenefit" xlink:to="us-gaap_DeferredFederalIncomeTaxExpenseBenefit_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_DeferredFederalIncomeTaxExpenseBenefit_lbl" xml:lang="en-US"> Deferred Federal Income Tax Expense (Benefit) </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/verboseLabel" xlink:label="us-gaap_DeferredFederalIncomeTaxExpenseBenefit_lbl" xml:lang="en-US"> Federal </label>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DeferredStateAndLocalIncomeTaxExpenseBenefit" xlink:label="us-gaap_DeferredStateAndLocalIncomeTaxExpenseBenefit"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_DeferredStateAndLocalIncomeTaxExpenseBenefit" xlink:to="us-gaap_DeferredStateAndLocalIncomeTaxExpenseBenefit_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_DeferredStateAndLocalIncomeTaxExpenseBenefit_lbl" xml:lang="en-US"> Deferred State and Local Income Tax Expense (Benefit) </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/verboseLabel" xlink:label="us-gaap_DeferredStateAndLocalIncomeTaxExpenseBenefit_lbl" xml:lang="en-US"> State and local </label>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_EffectiveIncomeTaxRateContinuingOperationsTaxRateReconciliationAbstract" xlink:label="us-gaap_EffectiveIncomeTaxRateContinuingOperationsTaxRateReconciliationAbstract"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_EffectiveIncomeTaxRateContinuingOperationsTaxRateReconciliationAbstract" xlink:to="us-gaap_EffectiveIncomeTaxRateContinuingOperationsTaxRateReconciliationAbstract_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_EffectiveIncomeTaxRateContinuingOperationsTaxRateReconciliationAbstract_lbl" xml:lang="en-US"> Effective Income Tax Rate Reconciliation, Percent [Abstract] </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/verboseLabel" xlink:label="us-gaap_EffectiveIncomeTaxRateContinuingOperationsTaxRateReconciliationAbstract_lbl" xml:lang="en-US"> Income tax rates </label>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_EffectiveIncomeTaxRateReconciliationAtFederalStatutoryIncomeTaxRate" xlink:label="us-gaap_EffectiveIncomeTaxRateReconciliationAtFederalStatutoryIncomeTaxRate"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_EffectiveIncomeTaxRateReconciliationAtFederalStatutoryIncomeTaxRate" xlink:to="us-gaap_EffectiveIncomeTaxRateReconciliationAtFederalStatutoryIncomeTaxRate_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_EffectiveIncomeTaxRateReconciliationAtFederalStatutoryIncomeTaxRate_lbl" xml:lang="en-US"> Effective Income Tax Rate Reconciliation, at Federal Statutory Income Tax Rate, Percent </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/verboseLabel" xlink:label="us-gaap_EffectiveIncomeTaxRateReconciliationAtFederalStatutoryIncomeTaxRate_lbl" xml:lang="en-US"> - Statutory U.S. federal rate </label>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_EffectiveIncomeTaxRateReconciliationStateAndLocalIncomeTaxes" xlink:label="us-gaap_EffectiveIncomeTaxRateReconciliationStateAndLocalIncomeTaxes"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_EffectiveIncomeTaxRateReconciliationStateAndLocalIncomeTaxes" xlink:to="us-gaap_EffectiveIncomeTaxRateReconciliationStateAndLocalIncomeTaxes_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_EffectiveIncomeTaxRateReconciliationStateAndLocalIncomeTaxes_lbl" xml:lang="en-US"> Effective Income Tax Rate Reconciliation, State and Local Income Taxes, Percent </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/verboseLabel" xlink:label="us-gaap_EffectiveIncomeTaxRateReconciliationStateAndLocalIncomeTaxes_lbl" xml:lang="en-US"> - State income taxes, net of federal benefit </label>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_EffectiveIncomeTaxRateReconciliationNondeductibleExpenseShareBasedCompensationCost" xlink:label="us-gaap_EffectiveIncomeTaxRateReconciliationNondeductibleExpenseShareBasedCompensationCost"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_EffectiveIncomeTaxRateReconciliationNondeductibleExpenseShareBasedCompensationCost" xlink:to="us-gaap_EffectiveIncomeTaxRateReconciliationNondeductibleExpenseShareBasedCompensationCost_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_EffectiveIncomeTaxRateReconciliationNondeductibleExpenseShareBasedCompensationCost_lbl" xml:lang="en-US"> Effective Income Tax Rate Reconciliation, Nondeductible Expense, Share-based Compensation Cost, Percent </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/verboseLabel" xlink:label="us-gaap_EffectiveIncomeTaxRateReconciliationNondeductibleExpenseShareBasedCompensationCost_lbl" xml:lang="en-US"> - Excess tax benefits related to stock compensation </label>
<loc xlink:type="locator" xlink:href="hdsn-20201231.xsd#hdsn_EffectiveIncomeTaxRateReconciliationAlternativeMinimumTaxCreditAndNetOperatingLossPercent" xlink:label="hdsn_EffectiveIncomeTaxRateReconciliationAlternativeMinimumTaxCreditAndNetOperatingLossPercent"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="hdsn_EffectiveIncomeTaxRateReconciliationAlternativeMinimumTaxCreditAndNetOperatingLossPercent" xlink:to="hdsn_EffectiveIncomeTaxRateReconciliationAlternativeMinimumTaxCreditAndNetOperatingLossPercent_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:label="hdsn_EffectiveIncomeTaxRateReconciliationAlternativeMinimumTaxCreditAndNetOperatingLossPercent_lbl" xml:lang="en-US"> Percentage of the difference between reported income tax expense (benefit) and expected income tax expense (benefit) computed by applying the domestic federal statutory income tax rates to pretax income (loss) from continuing operations attributable to alternative minimum tax credit and net operating loss (NOL) carryback. </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="hdsn_EffectiveIncomeTaxRateReconciliationAlternativeMinimumTaxCreditAndNetOperatingLossPercent_lbl" xml:lang="en-US"> Effective Income Tax Rate Reconciliation Alternative Minimum Tax Credit And Net Operating Loss Percent </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="hdsn_EffectiveIncomeTaxRateReconciliationAlternativeMinimumTaxCreditAndNetOperatingLossPercent_lbl" xml:lang="en-US"> - AMT credit and NOL Carryback </label>
<loc xlink:type="locator" xlink:href="hdsn-20201231.xsd#hdsn_EffectiveIncomeTaxRateReconciliationLobbyingPercent" xlink:label="hdsn_EffectiveIncomeTaxRateReconciliationLobbyingPercent"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="hdsn_EffectiveIncomeTaxRateReconciliationLobbyingPercent" xlink:to="hdsn_EffectiveIncomeTaxRateReconciliationLobbyingPercent_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:label="hdsn_EffectiveIncomeTaxRateReconciliationLobbyingPercent_lbl" xml:lang="en-US"> Percentage of the difference between reported income tax expense (benefit) and expected income tax expense (benefit) computed by applying the domestic federal statutory income tax rates to pretax income (loss) from continuing operations attributable to lobbying. </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="hdsn_EffectiveIncomeTaxRateReconciliationLobbyingPercent_lbl" xml:lang="en-US"> Effective Income Tax Rate Reconciliation, Lobbying, Percent </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="hdsn_EffectiveIncomeTaxRateReconciliationLobbyingPercent_lbl" xml:lang="en-US"> - Lobbying </label>
<loc xlink:type="locator" xlink:href="hdsn-20201231.xsd#hdsn_EffectiveIncomeTaxRateReconciliationMealsAndEntertainmentPercent" xlink:label="hdsn_EffectiveIncomeTaxRateReconciliationMealsAndEntertainmentPercent"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="hdsn_EffectiveIncomeTaxRateReconciliationMealsAndEntertainmentPercent" xlink:to="hdsn_EffectiveIncomeTaxRateReconciliationMealsAndEntertainmentPercent_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:label="hdsn_EffectiveIncomeTaxRateReconciliationMealsAndEntertainmentPercent_lbl" xml:lang="en-US"> Percentage of the difference between reported income tax expense (benefit) and expected income tax expense (benefit) computed by applying the domestic federal statutory income tax rates to pretax income (loss) from continuing operations attributable to Meals & Entertainment. </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="hdsn_EffectiveIncomeTaxRateReconciliationMealsAndEntertainmentPercent_lbl" xml:lang="en-US"> Effective Income Tax Rate Reconciliation, Meals And Entertainment, Percent </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="hdsn_EffectiveIncomeTaxRateReconciliationMealsAndEntertainmentPercent_lbl" xml:lang="en-US"> - Meals & Entertainment </label>
<loc xlink:type="locator" xlink:href="hdsn-20201231.xsd#hdsn_EffectiveIncomeTaxRateReconciliationOfficerSLifeInsurancePercent" xlink:label="hdsn_EffectiveIncomeTaxRateReconciliationOfficerSLifeInsurancePercent"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="hdsn_EffectiveIncomeTaxRateReconciliationOfficerSLifeInsurancePercent" xlink:to="hdsn_EffectiveIncomeTaxRateReconciliationOfficerSLifeInsurancePercent_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:label="hdsn_EffectiveIncomeTaxRateReconciliationOfficerSLifeInsurancePercent_lbl" xml:lang="en-US"> Percentage of the difference between reported income tax expense (benefit) and expected income tax expense (benefit) computed by applying the domestic federal statutory income tax rates to pretax income (loss) from continuing operations attributable to Officer's Life Insurance. </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="hdsn_EffectiveIncomeTaxRateReconciliationOfficerSLifeInsurancePercent_lbl" xml:lang="en-US"> Effective Income Tax Rate Reconciliation, Officer's Life Insurance, Percent </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="hdsn_EffectiveIncomeTaxRateReconciliationOfficerSLifeInsurancePercent_lbl" xml:lang="en-US"> - Officer's Life Insurance </label>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_EffectiveIncomeTaxRateReconciliationChangeInDeferredTaxAssetsValuationAllowance" xlink:label="us-gaap_EffectiveIncomeTaxRateReconciliationChangeInDeferredTaxAssetsValuationAllowance"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_EffectiveIncomeTaxRateReconciliationChangeInDeferredTaxAssetsValuationAllowance" xlink:to="us-gaap_EffectiveIncomeTaxRateReconciliationChangeInDeferredTaxAssetsValuationAllowance_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_EffectiveIncomeTaxRateReconciliationChangeInDeferredTaxAssetsValuationAllowance_lbl" xml:lang="en-US"> Effective Income Tax Rate Reconciliation, Change in Deferred Tax Assets Valuation Allowance, Percent </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/verboseLabel" xlink:label="us-gaap_EffectiveIncomeTaxRateReconciliationChangeInDeferredTaxAssetsValuationAllowance_lbl" xml:lang="en-US"> - Change in valuation allowance </label>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_EffectiveIncomeTaxRateContinuingOperations" xlink:label="us-gaap_EffectiveIncomeTaxRateContinuingOperations"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_EffectiveIncomeTaxRateContinuingOperations" xlink:to="us-gaap_EffectiveIncomeTaxRateContinuingOperations_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_EffectiveIncomeTaxRateContinuingOperations_lbl" xml:lang="en-US"> Effective Income Tax Rate Reconciliation, Percent </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/totalLabel" xlink:label="us-gaap_EffectiveIncomeTaxRateContinuingOperations_lbl" xml:lang="en-US"> Total </label>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DeferredTaxAssetsTaxDeferredExpenseReservesAndAccrualsAbstract" xlink:label="us-gaap_DeferredTaxAssetsTaxDeferredExpenseReservesAndAccrualsAbstract"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_DeferredTaxAssetsTaxDeferredExpenseReservesAndAccrualsAbstract" xlink:to="us-gaap_DeferredTaxAssetsTaxDeferredExpenseReservesAndAccrualsAbstract_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_DeferredTaxAssetsTaxDeferredExpenseReservesAndAccrualsAbstract_lbl" xml:lang="en-US"> Deferred Tax Assets, Tax Deferred Expense, Reserves and Accruals [Abstract] </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/verboseLabel" xlink:label="us-gaap_DeferredTaxAssetsTaxDeferredExpenseReservesAndAccrualsAbstract_lbl" xml:lang="en-US"> Deferred income tax assets (liabilities) </label>
<loc xlink:type="locator" xlink:href="hdsn-20201231.xsd#hdsn_DeferredTaxAssetsTaxDeferredExpenseReservesAndAccrualsDepreciationAndAmortization" xlink:label="hdsn_DeferredTaxAssetsTaxDeferredExpenseReservesAndAccrualsDepreciationAndAmortization"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="hdsn_DeferredTaxAssetsTaxDeferredExpenseReservesAndAccrualsDepreciationAndAmortization" xlink:to="hdsn_DeferredTaxAssetsTaxDeferredExpenseReservesAndAccrualsDepreciationAndAmortization_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:label="hdsn_DeferredTaxAssetsTaxDeferredExpenseReservesAndAccrualsDepreciationAndAmortization_lbl" xml:lang="en-US"> Deferred Tax Assets Tax Deferred Expense Reserves And Accruals Depreciation And Amortization. </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="hdsn_DeferredTaxAssetsTaxDeferredExpenseReservesAndAccrualsDepreciationAndAmortization_lbl" xml:lang="en-US"> Deferred Tax Assets Tax Deferred Expense Reserves And Accruals Depreciation And Amortization </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/verboseLabel" xlink:label="hdsn_DeferredTaxAssetsTaxDeferredExpenseReservesAndAccrualsDepreciationAndAmortization_lbl" xml:lang="en-US"> - Depreciation & amortization </label>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DeferredTaxAssetsTaxDeferredExpenseReservesAndAccrualsAllowanceForDoubtfulAccounts" xlink:label="us-gaap_DeferredTaxAssetsTaxDeferredExpenseReservesAndAccrualsAllowanceForDoubtfulAccounts"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_DeferredTaxAssetsTaxDeferredExpenseReservesAndAccrualsAllowanceForDoubtfulAccounts" xlink:to="us-gaap_DeferredTaxAssetsTaxDeferredExpenseReservesAndAccrualsAllowanceForDoubtfulAccounts_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_DeferredTaxAssetsTaxDeferredExpenseReservesAndAccrualsAllowanceForDoubtfulAccounts_lbl" xml:lang="en-US"> Deferred Tax Assets, Tax Deferred Expense, Reserves and Accruals, Allowance for Doubtful Accounts </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/verboseLabel" xlink:label="us-gaap_DeferredTaxAssetsTaxDeferredExpenseReservesAndAccrualsAllowanceForDoubtfulAccounts_lbl" xml:lang="en-US"> - Reserves for doubtful accounts </label>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DeferredTaxAssetsTaxDeferredExpenseReservesAndAccrualsReserves" xlink:label="us-gaap_DeferredTaxAssetsTaxDeferredExpenseReservesAndAccrualsReserves"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_DeferredTaxAssetsTaxDeferredExpenseReservesAndAccrualsReserves" xlink:to="us-gaap_DeferredTaxAssetsTaxDeferredExpenseReservesAndAccrualsReserves_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_DeferredTaxAssetsTaxDeferredExpenseReservesAndAccrualsReserves_lbl" xml:lang="en-US"> Deferred Tax Assets, Tax Deferred Expense, Reserves and Accruals, Reserves </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/verboseLabel" xlink:label="us-gaap_DeferredTaxAssetsTaxDeferredExpenseReservesAndAccrualsReserves_lbl" xml:lang="en-US"> - Inventory reserve </label>
<loc xlink:type="locator" xlink:href="hdsn-20201231.xsd#hdsn_DeferredTaxAssetsTaxDeferredExpenseReservesAndNonQualifiedStockOptions" xlink:label="hdsn_DeferredTaxAssetsTaxDeferredExpenseReservesAndNonQualifiedStockOptions"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="hdsn_DeferredTaxAssetsTaxDeferredExpenseReservesAndNonQualifiedStockOptions" xlink:to="hdsn_DeferredTaxAssetsTaxDeferredExpenseReservesAndNonQualifiedStockOptions_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:label="hdsn_DeferredTaxAssetsTaxDeferredExpenseReservesAndNonQualifiedStockOptions_lbl" xml:lang="en-US"> It represents Deferred Tax Assets Tax Deferred Expense Reserves And Non Qualified Stock Options. </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="hdsn_DeferredTaxAssetsTaxDeferredExpenseReservesAndNonQualifiedStockOptions_lbl" xml:lang="en-US"> Deferred Tax Assets Tax Deferred Expense Reserves And Non Qualified Stock Options </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/verboseLabel" xlink:label="hdsn_DeferredTaxAssetsTaxDeferredExpenseReservesAndNonQualifiedStockOptions_lbl" xml:lang="en-US"> - Non qualified stock options </label>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DeferredTaxAssetsOperatingLossCarryforwards" xlink:label="us-gaap_DeferredTaxAssetsOperatingLossCarryforwards"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_DeferredTaxAssetsOperatingLossCarryforwards" xlink:to="us-gaap_DeferredTaxAssetsOperatingLossCarryforwards_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_DeferredTaxAssetsOperatingLossCarryforwards_lbl" xml:lang="en-US"> Deferred Tax Assets, Operating Loss Carryforwards </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/verboseLabel" xlink:label="us-gaap_DeferredTaxAssetsOperatingLossCarryforwards_lbl" xml:lang="en-US"> - Net operating losses </label>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DeferredTaxAssetsTaxCreditCarryforwardsAlternativeMinimumTax" xlink:label="us-gaap_DeferredTaxAssetsTaxCreditCarryforwardsAlternativeMinimumTax"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_DeferredTaxAssetsTaxCreditCarryforwardsAlternativeMinimumTax" xlink:to="us-gaap_DeferredTaxAssetsTaxCreditCarryforwardsAlternativeMinimumTax_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_DeferredTaxAssetsTaxCreditCarryforwardsAlternativeMinimumTax_lbl" xml:lang="en-US"> Deferred Tax Assets, Tax Credit Carryforwards, Alternative Minimum Tax </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/verboseLabel" xlink:label="us-gaap_DeferredTaxAssetsTaxCreditCarryforwardsAlternativeMinimumTax_lbl" xml:lang="en-US"> - Amt credit </label>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DeferredTaxAssetsDeferredIncome" xlink:label="us-gaap_DeferredTaxAssetsDeferredIncome"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_DeferredTaxAssetsDeferredIncome" xlink:to="us-gaap_DeferredTaxAssetsDeferredIncome_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_DeferredTaxAssetsDeferredIncome_lbl" xml:lang="en-US"> Deferred Tax Assets, Deferred Income </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/verboseLabel" xlink:label="us-gaap_DeferredTaxAssetsDeferredIncome_lbl" xml:lang="en-US"> - Deferred interest </label>
<loc xlink:type="locator" xlink:href="hdsn-20201231.xsd#hdsn_DeferredTaxAssetsDeferredBonus" xlink:label="hdsn_DeferredTaxAssetsDeferredBonus"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="hdsn_DeferredTaxAssetsDeferredBonus" xlink:to="hdsn_DeferredTaxAssetsDeferredBonus_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:label="hdsn_DeferredTaxAssetsDeferredBonus_lbl" xml:lang="en-US"> Amount of deferred tax assets deferred income. </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="hdsn_DeferredTaxAssetsDeferredBonus_lbl" xml:lang="en-US"> Deferred Tax Assets Deferred Bonus </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="hdsn_DeferredTaxAssetsDeferredBonus_lbl" xml:lang="en-US"> - Deferred bonus </label>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DeferredTaxLiabilities" xlink:label="us-gaap_DeferredTaxLiabilities"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_DeferredTaxLiabilities" xlink:to="us-gaap_DeferredTaxLiabilities_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_DeferredTaxLiabilities_lbl" xml:lang="en-US"> Deferred Tax Liabilities, Net </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2009/role/negatedTotalLabel" xlink:label="us-gaap_DeferredTaxLiabilities_lbl" xml:lang="en-US"> Total </label>
<loc xlink:type="locator" xlink:href="hdsn-20201231.xsd#hdsn_IncomeTaxLineItems" xlink:label="hdsn_IncomeTaxLineItems"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="hdsn_IncomeTaxLineItems" xlink:to="hdsn_IncomeTaxLineItems_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:label="hdsn_IncomeTaxLineItems_lbl" xml:lang="en-US"> IncomeTaxLineItems </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="hdsn_IncomeTaxLineItems_lbl" xml:lang="en-US"> Income Tax [Line Items] </label>
<loc xlink:type="locator" xlink:href="hdsn-20201231.xsd#hdsn_AnnualNolLimitationPercentageOfTaxEarnings" xlink:label="hdsn_AnnualNolLimitationPercentageOfTaxEarnings"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="hdsn_AnnualNolLimitationPercentageOfTaxEarnings" xlink:to="hdsn_AnnualNolLimitationPercentageOfTaxEarnings_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:label="hdsn_AnnualNolLimitationPercentageOfTaxEarnings_lbl" xml:lang="en-US"> The percentage of tax earnings limiting the amount of NOL's allowed on an annual basis. </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="hdsn_AnnualNolLimitationPercentageOfTaxEarnings_lbl" xml:lang="en-US"> Annual NOL Limitation Percentage Of Tax Earnings </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="hdsn_AnnualNolLimitationPercentageOfTaxEarnings_lbl" xml:lang="en-US"> Percentage of tax earnings </label>
<loc xlink:type="locator" xlink:href="hdsn-20201231.xsd#hdsn_OperatingLossLimitation" xlink:label="hdsn_OperatingLossLimitation"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="hdsn_OperatingLossLimitation" xlink:to="hdsn_OperatingLossLimitation_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:label="hdsn_OperatingLossLimitation_lbl" xml:lang="en-US"> The amount of annual loss limitations to which the expiring NOLs are subject. </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="hdsn_OperatingLossLimitation_lbl" xml:lang="en-US"> Operating Loss Limitation </label>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ScheduleOfFiniteLivedIntangibleAssetsTable" xlink:label="us-gaap_ScheduleOfFiniteLivedIntangibleAssetsTable"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_ScheduleOfFiniteLivedIntangibleAssetsTable" xlink:to="us-gaap_ScheduleOfFiniteLivedIntangibleAssetsTable_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_ScheduleOfFiniteLivedIntangibleAssetsTable_lbl" xml:lang="en-US"> Schedule of Finite-Lived Intangible Assets [Table] </label>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis" xlink:label="us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis" xlink:to="us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_lbl" xml:lang="en-US"> Finite-Lived Intangible Assets by Major Class [Axis] </label>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain" xlink:label="us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain" xlink:to="us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_lbl" xml:lang="en-US"> Finite Lived Intangible Assets Major Class Name [Domain] </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_lbl" xml:lang="en-US"> Finite-Lived Intangible Assets, Major Class Name [Domain] </label>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_PatentsMember" xlink:label="us-gaap_PatentsMember"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_PatentsMember" xlink:to="us-gaap_PatentsMember_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_PatentsMember_lbl" xml:lang="en-US"> Patents [Member] </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_PatentsMember_lbl" xml:lang="en-US"> Patents [Member] </label>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_NoncompeteAgreementsMember" xlink:label="us-gaap_NoncompeteAgreementsMember"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_NoncompeteAgreementsMember" xlink:to="us-gaap_NoncompeteAgreementsMember_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_NoncompeteAgreementsMember_lbl" xml:lang="en-US"> Noncompete Agreements [Member] </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_NoncompeteAgreementsMember_lbl" xml:lang="en-US"> Covenant not to compete [Member] </label>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_CustomerRelationshipsMember" xlink:label="us-gaap_CustomerRelationshipsMember"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_CustomerRelationshipsMember" xlink:to="us-gaap_CustomerRelationshipsMember_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_CustomerRelationshipsMember_lbl" xml:lang="en-US"> Customer Relationships [Member] </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_CustomerRelationshipsMember_lbl" xml:lang="en-US"> Customer relationships [Member] </label>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_AboveMarketLeasesMember" xlink:label="us-gaap_AboveMarketLeasesMember"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_AboveMarketLeasesMember" xlink:to="us-gaap_AboveMarketLeasesMember_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_AboveMarketLeasesMember_lbl" xml:lang="en-US"> Above Market Leases [Member] </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_AboveMarketLeasesMember_lbl" xml:lang="en-US"> Above market leases [Member] </label>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ResearchAndDevelopmentArrangementContractToPerformForOthersByTypeAxis" xlink:label="us-gaap_ResearchAndDevelopmentArrangementContractToPerformForOthersByTypeAxis"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_ResearchAndDevelopmentArrangementContractToPerformForOthersByTypeAxis" xlink:to="us-gaap_ResearchAndDevelopmentArrangementContractToPerformForOthersByTypeAxis_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_ResearchAndDevelopmentArrangementContractToPerformForOthersByTypeAxis_lbl" xml:lang="en-US"> Research and Development Arrangement, Contract to Perform for Others, Type [Axis] </label>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ResearchAndDevelopmentArrangementContractToPerformForOthersTypeDomain" xlink:label="us-gaap_ResearchAndDevelopmentArrangementContractToPerformForOthersTypeDomain"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_ResearchAndDevelopmentArrangementContractToPerformForOthersTypeDomain" xlink:to="us-gaap_ResearchAndDevelopmentArrangementContractToPerformForOthersTypeDomain_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_ResearchAndDevelopmentArrangementContractToPerformForOthersTypeDomain_lbl" xml:lang="en-US"> Research And Development Arrangement Contract To Perform For Others Type [Domain] </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_ResearchAndDevelopmentArrangementContractToPerformForOthersTypeDomain_lbl" xml:lang="en-US"> Research and Development Arrangement, Contract to Perform for Others, Type [Domain] </label>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_LicenseAgreementTermsMember" xlink:label="us-gaap_LicenseAgreementTermsMember"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_LicenseAgreementTermsMember" xlink:to="us-gaap_LicenseAgreementTermsMember_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_LicenseAgreementTermsMember_lbl" xml:lang="en-US"> License Agreement Terms [Member] </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_LicenseAgreementTermsMember_lbl" xml:lang="en-US"> Licenses [Member] </label>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_FiniteLivedIntangibleAssetsLineItems" xlink:label="us-gaap_FiniteLivedIntangibleAssetsLineItems"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_FiniteLivedIntangibleAssetsLineItems" xlink:to="us-gaap_FiniteLivedIntangibleAssetsLineItems_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_FiniteLivedIntangibleAssetsLineItems_lbl" xml:lang="en-US"> Finite-Lived Intangible Assets [Line Items] </label>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_FiniteLivedIntangibleAssetsRemainingAmortizationPeriod1" xlink:label="us-gaap_FiniteLivedIntangibleAssetsRemainingAmortizationPeriod1"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_FiniteLivedIntangibleAssetsRemainingAmortizationPeriod1" xlink:to="us-gaap_FiniteLivedIntangibleAssetsRemainingAmortizationPeriod1_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_FiniteLivedIntangibleAssetsRemainingAmortizationPeriod1_lbl" xml:lang="en-US"> Finite-Lived Intangible Assets, Remaining Amortization Period </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_FiniteLivedIntangibleAssetsRemainingAmortizationPeriod1_lbl" xml:lang="en-US"> Amortization Period (in years) </label>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_FiniteLivedIntangibleAssetsGross" xlink:label="us-gaap_FiniteLivedIntangibleAssetsGross"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_FiniteLivedIntangibleAssetsGross" xlink:to="us-gaap_FiniteLivedIntangibleAssetsGross_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_FiniteLivedIntangibleAssetsGross_lbl" xml:lang="en-US"> Finite-Lived Intangible Assets, Gross </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_FiniteLivedIntangibleAssetsGross_lbl" xml:lang="en-US"> Gross Carrying Amount </label>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_FiniteLivedIntangibleAssetsAccumulatedAmortization" xlink:label="us-gaap_FiniteLivedIntangibleAssetsAccumulatedAmortization"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_FiniteLivedIntangibleAssetsAccumulatedAmortization" xlink:to="us-gaap_FiniteLivedIntangibleAssetsAccumulatedAmortization_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_FiniteLivedIntangibleAssetsAccumulatedAmortization_lbl" xml:lang="en-US"> Finite-Lived Intangible Assets, Accumulated Amortization </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_FiniteLivedIntangibleAssetsAccumulatedAmortization_lbl" xml:lang="en-US"> Accumulated amortization </label>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_FiniteLivedIntangibleAssetsNet" xlink:label="us-gaap_FiniteLivedIntangibleAssetsNet"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_FiniteLivedIntangibleAssetsNet" xlink:to="us-gaap_FiniteLivedIntangibleAssetsNet_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_FiniteLivedIntangibleAssetsNet_lbl" xml:lang="en-US"> Finite-Lived Intangible Assets, Net, Total </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/totalLabel" xlink:label="us-gaap_FiniteLivedIntangibleAssetsNet_lbl" xml:lang="en-US"> Net </label>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseNextTwelveMonths" xlink:label="us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseNextTwelveMonths"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseNextTwelveMonths" xlink:to="us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseNextTwelveMonths_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseNextTwelveMonths_lbl" xml:lang="en-US"> Finite-Lived Intangible Assets, Amortization Expense, Next Twelve Months </label>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseYearTwo" xlink:label="us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseYearTwo"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseYearTwo" xlink:to="us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseYearTwo_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseYearTwo_lbl" xml:lang="en-US"> Finite-Lived Intangible Assets, Amortization Expense, Year Two </label>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseYearThree" xlink:label="us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseYearThree"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseYearThree" xlink:to="us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseYearThree_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseYearThree_lbl" xml:lang="en-US"> Finite-Lived Intangible Assets, Amortization Expense, Year Three </label>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseYearFour" xlink:label="us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseYearFour"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseYearFour" xlink:to="us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseYearFour_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseYearFour_lbl" xml:lang="en-US"> Finite-Lived Intangible Assets, Amortization Expense, Year Four </label>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseYearFive" xlink:label="us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseYearFive"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseYearFive" xlink:to="us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseYearFive_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseYearFive_lbl" xml:lang="en-US"> Finite-Lived Intangible Assets, Amortization Expense, Year Five </label>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseAfterYearFive" xlink:label="us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseAfterYearFive"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseAfterYearFive" xlink:to="us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseAfterYearFive_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseAfterYearFive_lbl" xml:lang="en-US"> Finite-Lived Intangible Assets, Amortization Expense, after Year Five </label>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ShortTermBorrowingsAbstract" xlink:label="us-gaap_ShortTermBorrowingsAbstract"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_ShortTermBorrowingsAbstract" xlink:to="us-gaap_ShortTermBorrowingsAbstract_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_ShortTermBorrowingsAbstract_lbl" xml:lang="en-US"> Short-term Debt [Abstract] </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/verboseLabel" xlink:label="us-gaap_ShortTermBorrowingsAbstract_lbl" xml:lang="en-US"> Short-term debt: </label>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_LinesOfCreditCurrent" xlink:label="us-gaap_LinesOfCreditCurrent"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_LinesOfCreditCurrent" xlink:to="us-gaap_LinesOfCreditCurrent_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_LinesOfCreditCurrent_lbl" xml:lang="en-US"> Line of Credit, Current </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/verboseLabel" xlink:label="us-gaap_LinesOfCreditCurrent_lbl" xml:lang="en-US"> - Revolving credit line and other debt </label>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_UnsecuredDebtCurrent" xlink:label="us-gaap_UnsecuredDebtCurrent"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_UnsecuredDebtCurrent" xlink:to="us-gaap_UnsecuredDebtCurrent_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_UnsecuredDebtCurrent_lbl" xml:lang="en-US"> Unsecured Debt, Current </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_UnsecuredDebtCurrent_lbl" xml:lang="en-US"> - Loan from Paycheck Protection Program- current </label>
<loc xlink:type="locator" xlink:href="hdsn-20201231.xsd#hdsn_CapitalLeaseObligationCurrent" xlink:label="hdsn_CapitalLeaseObligationCurrent"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="hdsn_CapitalLeaseObligationCurrent" xlink:to="hdsn_CapitalLeaseObligationCurrent_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:label="hdsn_CapitalLeaseObligationCurrent_lbl" xml:lang="en-US"> The amount of capital lease obligation due within one year or the normal operating cycle, if longer. </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="hdsn_CapitalLeaseObligationCurrent_lbl" xml:lang="en-US"> Capital Lease Obligation, Current </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="hdsn_CapitalLeaseObligationCurrent_lbl" xml:lang="en-US"> - Capital lease obligation- current </label>
<loc xlink:type="locator" xlink:href="hdsn-20201231.xsd#hdsn_LongtermDebtCurrentNetOfOtherDebt" xlink:label="hdsn_LongtermDebtCurrentNetOfOtherDebt"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="hdsn_LongtermDebtCurrentNetOfOtherDebt" xlink:to="hdsn_LongtermDebtCurrentNetOfOtherDebt_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:label="hdsn_LongtermDebtCurrentNetOfOtherDebt_lbl" xml:lang="en-US"> Its represent the amount of long-term debt current net of other debt. </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="hdsn_LongtermDebtCurrentNetOfOtherDebt_lbl" xml:lang="en-US"> Long-term Debt Current Net of Other Debt </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/verboseLabel" xlink:label="hdsn_LongtermDebtCurrentNetOfOtherDebt_lbl" xml:lang="en-US"> - Term loan facility-current </label>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DebtCurrent" xlink:label="us-gaap_DebtCurrent"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_DebtCurrent" xlink:to="us-gaap_DebtCurrent_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_DebtCurrent_lbl" xml:lang="en-US"> Debt, Current, Total </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/totalLabel" xlink:label="us-gaap_DebtCurrent_lbl" xml:lang="en-US"> Subtotal </label>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_LongTermDebtAbstract" xlink:label="us-gaap_LongTermDebtAbstract"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_LongTermDebtAbstract" xlink:to="us-gaap_LongTermDebtAbstract_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_LongTermDebtAbstract_lbl" xml:lang="en-US"> Long-term Debt, Unclassified [Abstract] </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/verboseLabel" xlink:label="us-gaap_LongTermDebtAbstract_lbl" xml:lang="en-US"> Long-term debt: </label>
<loc xlink:type="locator" xlink:href="hdsn-20201231.xsd#hdsn_LongTermDebtNonCurrentNetOfOtherDebt" xlink:label="hdsn_LongTermDebtNonCurrentNetOfOtherDebt"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="hdsn_LongTermDebtNonCurrentNetOfOtherDebt" xlink:to="hdsn_LongTermDebtNonCurrentNetOfOtherDebt_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:label="hdsn_LongTermDebtNonCurrentNetOfOtherDebt_lbl" xml:lang="en-US"> Its represent the amount of long-term debt non current net of other debt. </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="hdsn_LongTermDebtNonCurrentNetOfOtherDebt_lbl" xml:lang="en-US"> Long Term Debt Non Current Net of Other Debt </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/verboseLabel" xlink:label="hdsn_LongTermDebtNonCurrentNetOfOtherDebt_lbl" xml:lang="en-US"> - Term loan facility- net of current portion of long-term debt </label>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_UnsecuredLongTermDebt" xlink:label="us-gaap_UnsecuredLongTermDebt"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_UnsecuredLongTermDebt" xlink:to="us-gaap_UnsecuredLongTermDebt_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_UnsecuredLongTermDebt_lbl" xml:lang="en-US"> Unsecured Long-term Debt, Noncurrent </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_UnsecuredLongTermDebt_lbl" xml:lang="en-US"> - Loan from Paycheck Protection Program- net of current portion </label>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_CapitalLeaseObligationsNoncurrent" xlink:label="us-gaap_CapitalLeaseObligationsNoncurrent"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_CapitalLeaseObligationsNoncurrent" xlink:to="us-gaap_CapitalLeaseObligationsNoncurrent_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_CapitalLeaseObligationsNoncurrent_lbl" xml:lang="en-US"> Capital Lease Obligations, Noncurrent </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/verboseLabel" xlink:label="us-gaap_CapitalLeaseObligationsNoncurrent_lbl" xml:lang="en-US"> - Capital lease obligations </label>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DeferredFinanceCostsNoncurrentNet" xlink:label="us-gaap_DeferredFinanceCostsNoncurrentNet"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_DeferredFinanceCostsNoncurrentNet" xlink:to="us-gaap_DeferredFinanceCostsNoncurrentNet_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_DeferredFinanceCostsNoncurrentNet_lbl" xml:lang="en-US"> Debt Issuance Costs, Noncurrent, Net </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2009/role/negatedLabel" xlink:label="us-gaap_DeferredFinanceCostsNoncurrentNet_lbl" xml:lang="en-US"> - Less: deferred financing costs on term loan </label>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DebtLongtermAndShorttermCombinedAmount" xlink:label="us-gaap_DebtLongtermAndShorttermCombinedAmount"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_DebtLongtermAndShorttermCombinedAmount" xlink:to="us-gaap_DebtLongtermAndShorttermCombinedAmount_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_DebtLongtermAndShorttermCombinedAmount_lbl" xml:lang="en-US"> Debt, Long-term and Short-term, Combined Amount </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/totalLabel" xlink:label="us-gaap_DebtLongtermAndShorttermCombinedAmount_lbl" xml:lang="en-US"> Total short-term & long-term debt </label>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_LongTermDebtAndCapitalLeaseObligationsRepaymentsOfPrincipalInNextTwelveMonths" xlink:label="us-gaap_LongTermDebtAndCapitalLeaseObligationsRepaymentsOfPrincipalInNextTwelveMonths"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_LongTermDebtAndCapitalLeaseObligationsRepaymentsOfPrincipalInNextTwelveMonths" xlink:to="us-gaap_LongTermDebtAndCapitalLeaseObligationsRepaymentsOfPrincipalInNextTwelveMonths_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_LongTermDebtAndCapitalLeaseObligationsRepaymentsOfPrincipalInNextTwelveMonths_lbl" xml:lang="en-US"> Long-term Debt and Capital Lease Obligations, Repayments of Principal in Next Twelve Months </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_LongTermDebtAndCapitalLeaseObligationsRepaymentsOfPrincipalInNextTwelveMonths_lbl" xml:lang="en-US"> -2021 </label>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_LongTermDebtAndCapitalLeaseObligationsMaturitiesRepaymentsOfPrincipalInYearTwo" xlink:label="us-gaap_LongTermDebtAndCapitalLeaseObligationsMaturitiesRepaymentsOfPrincipalInYearTwo"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_LongTermDebtAndCapitalLeaseObligationsMaturitiesRepaymentsOfPrincipalInYearTwo" xlink:to="us-gaap_LongTermDebtAndCapitalLeaseObligationsMaturitiesRepaymentsOfPrincipalInYearTwo_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_LongTermDebtAndCapitalLeaseObligationsMaturitiesRepaymentsOfPrincipalInYearTwo_lbl" xml:lang="en-US"> Long-term Debt and Capital Lease Obligations, Maturities, Repayments of Principal in Year Two </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_LongTermDebtAndCapitalLeaseObligationsMaturitiesRepaymentsOfPrincipalInYearTwo_lbl" xml:lang="en-US"> -2022 </label>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_LongTermDebtAndCapitalLeaseObligationsMaturitiesRepaymentsOfPrincipalInYearThree" xlink:label="us-gaap_LongTermDebtAndCapitalLeaseObligationsMaturitiesRepaymentsOfPrincipalInYearThree"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_LongTermDebtAndCapitalLeaseObligationsMaturitiesRepaymentsOfPrincipalInYearThree" xlink:to="us-gaap_LongTermDebtAndCapitalLeaseObligationsMaturitiesRepaymentsOfPrincipalInYearThree_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_LongTermDebtAndCapitalLeaseObligationsMaturitiesRepaymentsOfPrincipalInYearThree_lbl" xml:lang="en-US"> Long-term Debt and Capital Lease Obligations, Maturities, Repayments of Principal in Year Three </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_LongTermDebtAndCapitalLeaseObligationsMaturitiesRepaymentsOfPrincipalInYearThree_lbl" xml:lang="en-US"> -2023 </label>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_LongTermDebtAndCapitalLeaseObligations" xlink:label="us-gaap_LongTermDebtAndCapitalLeaseObligations"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_LongTermDebtAndCapitalLeaseObligations" xlink:to="us-gaap_LongTermDebtAndCapitalLeaseObligations_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_LongTermDebtAndCapitalLeaseObligations_lbl" xml:lang="en-US"> Long-term Debt and Capital Lease Obligations </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/totalLabel" xlink:label="us-gaap_LongTermDebtAndCapitalLeaseObligations_lbl" xml:lang="en-US"> Total </label>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity" xlink:label="us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity" xlink:to="us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity_lbl" xml:lang="en-US"> Line of Credit Facility, Maximum Borrowing Capacity </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity_lbl" xml:lang="en-US"> Line of Credit Facility, Maximum Borrowing Capacity </label>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DebtInstrumentBasisSpreadOnVariableRate1" xlink:label="us-gaap_DebtInstrumentBasisSpreadOnVariableRate1"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_DebtInstrumentBasisSpreadOnVariableRate1" xlink:to="us-gaap_DebtInstrumentBasisSpreadOnVariableRate1_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_DebtInstrumentBasisSpreadOnVariableRate1_lbl" xml:lang="en-US"> Debt Instrument, Basis Spread on Variable Rate </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_DebtInstrumentBasisSpreadOnVariableRate1_lbl" xml:lang="en-US"> Debt Instrument, Basis Spread on Variable Rate </label>
<loc xlink:type="locator" xlink:href="hdsn-20201231.xsd#hdsn_DebtInstrumentAdditionalPercentagePointsInterest" xlink:label="hdsn_DebtInstrumentAdditionalPercentagePointsInterest"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="hdsn_DebtInstrumentAdditionalPercentagePointsInterest" xlink:to="hdsn_DebtInstrumentAdditionalPercentagePointsInterest_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:label="hdsn_DebtInstrumentAdditionalPercentagePointsInterest_lbl" xml:lang="en-US"> Percentage points added to the calculated interest rate dependent on average quarterly undrawn availability. </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="hdsn_DebtInstrumentAdditionalPercentagePointsInterest_lbl" xml:lang="en-US"> Debt Instrument Additional Percentage Points Interest </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="hdsn_DebtInstrumentAdditionalPercentagePointsInterest_lbl" xml:lang="en-US"> Additional interest percentage </label>
<loc xlink:type="locator" xlink:href="hdsn-20201231.xsd#hdsn_RightToDominionInEventOfDefaultOrUndrawnAvailability" xlink:label="hdsn_RightToDominionInEventOfDefaultOrUndrawnAvailability"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="hdsn_RightToDominionInEventOfDefaultOrUndrawnAvailability" xlink:to="hdsn_RightToDominionInEventOfDefaultOrUndrawnAvailability_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:label="hdsn_RightToDominionInEventOfDefaultOrUndrawnAvailability_lbl" xml:lang="en-US"> Represents agent shall receive the right to dominion over certain of the Borrowers' bank accounts in the event of an Event of Default or if undrawn availability. </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="hdsn_RightToDominionInEventOfDefaultOrUndrawnAvailability_lbl" xml:lang="en-US"> Right to Dominion in The Event of Default or Undrawn Availability </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="hdsn_RightToDominionInEventOfDefaultOrUndrawnAvailability_lbl" xml:lang="en-US"> Right to dominion over certain borrower's bank accounts </label>
<loc xlink:type="locator" xlink:href="hdsn-20201231.xsd#hdsn_LineOfCreditFacilityCovenantComplianceMinimumLiquidityToBeDerivedFromAvailability" xlink:label="hdsn_LineOfCreditFacilityCovenantComplianceMinimumLiquidityToBeDerivedFromAvailability"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="hdsn_LineOfCreditFacilityCovenantComplianceMinimumLiquidityToBeDerivedFromAvailability" xlink:to="hdsn_LineOfCreditFacilityCovenantComplianceMinimumLiquidityToBeDerivedFromAvailability_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:label="hdsn_LineOfCreditFacilityCovenantComplianceMinimumLiquidityToBeDerivedFromAvailability_lbl" xml:lang="en-US"> Represents the minimum amount to be derived from availability. </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="hdsn_LineOfCreditFacilityCovenantComplianceMinimumLiquidityToBeDerivedFromAvailability_lbl" xml:lang="en-US"> Line of Credit Facility, Covenant Compliance, Minimum Liquidity to be Derived From Availability </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="hdsn_LineOfCreditFacilityCovenantComplianceMinimumLiquidityToBeDerivedFromAvailability_lbl" xml:lang="en-US"> Minimum amount to be derived from availability </label>
<loc xlink:type="locator" xlink:href="hdsn-20201231.xsd#hdsn_MinimumAggregateUndrawnLoanAvailability" xlink:label="hdsn_MinimumAggregateUndrawnLoanAvailability"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="hdsn_MinimumAggregateUndrawnLoanAvailability" xlink:to="hdsn_MinimumAggregateUndrawnLoanAvailability_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:label="hdsn_MinimumAggregateUndrawnLoanAvailability_lbl" xml:lang="en-US"> The minimum aggregate undrawn term loan availability used to determine percentage of excess cash flow to be used to paydown the loan. </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="hdsn_MinimumAggregateUndrawnLoanAvailability_lbl" xml:lang="en-US"> Minimum Aggregate Undrawn Loan Availability </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="hdsn_MinimumAggregateUndrawnLoanAvailability_lbl" xml:lang="en-US"> Minimum aggregate undrawn loan availability </label>
<loc xlink:type="locator" xlink:href="hdsn-20201231.xsd#hdsn_FixedChargesCoverageRatio" xlink:label="hdsn_FixedChargesCoverageRatio"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="hdsn_FixedChargesCoverageRatio" xlink:to="hdsn_FixedChargesCoverageRatio_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:label="hdsn_FixedChargesCoverageRatio_lbl" xml:lang="en-US"> Fixed charge coverage ratio reported during the year. </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="hdsn_FixedChargesCoverageRatio_lbl" xml:lang="en-US"> Fixed Charges Coverage Ratio </label>
<loc xlink:type="locator" xlink:href="hdsn-20201231.xsd#hdsn_PeriodForFixedChargeCoverageRatio" xlink:label="hdsn_PeriodForFixedChargeCoverageRatio"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="hdsn_PeriodForFixedChargeCoverageRatio" xlink:to="hdsn_PeriodForFixedChargeCoverageRatio_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:label="hdsn_PeriodForFixedChargeCoverageRatio_lbl" xml:lang="en-US"> Represents the period for FCCR covenant. </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="hdsn_PeriodForFixedChargeCoverageRatio_lbl" xml:lang="en-US"> Period For Fixed Charge Coverage Ratio </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="hdsn_PeriodForFixedChargeCoverageRatio_lbl" xml:lang="en-US"> Period for FCCR covenant </label>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_LineOfCreditFacilityInterestRateAtPeriodEnd" xlink:label="us-gaap_LineOfCreditFacilityInterestRateAtPeriodEnd"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_LineOfCreditFacilityInterestRateAtPeriodEnd" xlink:to="us-gaap_LineOfCreditFacilityInterestRateAtPeriodEnd_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_LineOfCreditFacilityInterestRateAtPeriodEnd_lbl" xml:lang="en-US"> Line of Credit Facility, Interest Rate at Period End </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_LineOfCreditFacilityInterestRateAtPeriodEnd_lbl" xml:lang="en-US"> Credit facility effective rate of interest </label>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DebtInstrumentFaceAmount" xlink:label="us-gaap_DebtInstrumentFaceAmount"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_DebtInstrumentFaceAmount" xlink:to="us-gaap_DebtInstrumentFaceAmount_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_DebtInstrumentFaceAmount_lbl" xml:lang="en-US"> Debt Instrument, Face Amount </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_DebtInstrumentFaceAmount_lbl" xml:lang="en-US"> Debt Instrument, Face Amount </label>
<loc xlink:type="locator" xlink:href="hdsn-20201231.xsd#hdsn_DebtInstrumentLineOfCreditFacilityPeriodicPaymentPrincipal" xlink:label="hdsn_DebtInstrumentLineOfCreditFacilityPeriodicPaymentPrincipal"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="hdsn_DebtInstrumentLineOfCreditFacilityPeriodicPaymentPrincipal" xlink:to="hdsn_DebtInstrumentLineOfCreditFacilityPeriodicPaymentPrincipal_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:label="hdsn_DebtInstrumentLineOfCreditFacilityPeriodicPaymentPrincipal_lbl" xml:lang="en-US"> Amount represents the information of principal repayments. </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="hdsn_DebtInstrumentLineOfCreditFacilityPeriodicPaymentPrincipal_lbl" xml:lang="en-US"> Debt Instrument, Line Of Credit Facility Periodic Payment Principal </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="hdsn_DebtInstrumentLineOfCreditFacilityPeriodicPaymentPrincipal_lbl" xml:lang="en-US"> Principal repayment </label>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DebtInstrumentInterestRateStatedPercentage" xlink:label="us-gaap_DebtInstrumentInterestRateStatedPercentage"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_DebtInstrumentInterestRateStatedPercentage" xlink:to="us-gaap_DebtInstrumentInterestRateStatedPercentage_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_DebtInstrumentInterestRateStatedPercentage_lbl" xml:lang="en-US"> Debt Instrument, Interest Rate, Stated Percentage </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_DebtInstrumentInterestRateStatedPercentage_lbl" xml:lang="en-US"> Debt Instrument, Interest Rate, Stated Percentage </label>
<loc xlink:type="locator" xlink:href="hdsn-20201231.xsd#hdsn_TotalLeverageRatio" xlink:label="hdsn_TotalLeverageRatio"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="hdsn_TotalLeverageRatio" xlink:to="hdsn_TotalLeverageRatio_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:label="hdsn_TotalLeverageRatio_lbl" xml:lang="en-US"> Represents the information pertaining to total leverage ratio. </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="hdsn_TotalLeverageRatio_lbl" xml:lang="en-US"> Total Leverage Ratio </label>
<loc xlink:type="locator" xlink:href="hdsn-20201231.xsd#hdsn_RatiosOfIndebtednessToNetCapital" xlink:label="hdsn_RatiosOfIndebtednessToNetCapital"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="hdsn_RatiosOfIndebtednessToNetCapital" xlink:to="hdsn_RatiosOfIndebtednessToNetCapital_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:label="hdsn_RatiosOfIndebtednessToNetCapital_lbl" xml:lang="en-US"> Indebtedness divided by net capitals. </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="hdsn_RatiosOfIndebtednessToNetCapital_lbl" xml:lang="en-US"> Ratios Of Indebtedness To Net Capital </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="hdsn_RatiosOfIndebtednessToNetCapital_lbl" xml:lang="en-US"> Ratios Of Indebtedness To Net Capital </label>
<loc xlink:type="locator" xlink:href="hdsn-20201231.xsd#hdsn_AnnualPrincipalPaymentPercentage" xlink:label="hdsn_AnnualPrincipalPaymentPercentage"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="hdsn_AnnualPrincipalPaymentPercentage" xlink:to="hdsn_AnnualPrincipalPaymentPercentage_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:label="hdsn_AnnualPrincipalPaymentPercentage_lbl" xml:lang="en-US"> The percent per annum of the original principal amount required as a principal payment on the loan. </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="hdsn_AnnualPrincipalPaymentPercentage_lbl" xml:lang="en-US"> Annual Principal Payment Percentage </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="hdsn_AnnualPrincipalPaymentPercentage_lbl" xml:lang="en-US"> Percent per annum </label>
<loc xlink:type="locator" xlink:href="hdsn-20201231.xsd#hdsn_PercentageExcessCashFlow" xlink:label="hdsn_PercentageExcessCashFlow"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="hdsn_PercentageExcessCashFlow" xlink:to="hdsn_PercentageExcessCashFlow_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:label="hdsn_PercentageExcessCashFlow_lbl" xml:lang="en-US"> The percentage of excess cash flow used to calculate the required additional annual principal payment. </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="hdsn_PercentageExcessCashFlow_lbl" xml:lang="en-US"> Percentage Excess Cash Flow </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="hdsn_PercentageExcessCashFlow_lbl" xml:lang="en-US"> Term Loan Facility- net of current portion of long-term debt </label>
<loc xlink:type="locator" xlink:href="hdsn-20201231.xsd#hdsn_DebtInstrumentLastTwelveMonthsAdjustedEarningsBeforeInterestTaxDepreciationAndAmortization" xlink:label="hdsn_DebtInstrumentLastTwelveMonthsAdjustedEarningsBeforeInterestTaxDepreciationAndAmortization"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="hdsn_DebtInstrumentLastTwelveMonthsAdjustedEarningsBeforeInterestTaxDepreciationAndAmortization" xlink:to="hdsn_DebtInstrumentLastTwelveMonthsAdjustedEarningsBeforeInterestTaxDepreciationAndAmortization_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:label="hdsn_DebtInstrumentLastTwelveMonthsAdjustedEarningsBeforeInterestTaxDepreciationAndAmortization_lbl" xml:lang="en-US"> The amount of LTM adjusted ebitda reported during the year. </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="hdsn_DebtInstrumentLastTwelveMonthsAdjustedEarningsBeforeInterestTaxDepreciationAndAmortization_lbl" xml:lang="en-US"> Debt Instrument, Last Twelve Months Adjusted Earnings Before Interest, Tax, Depreciation And Amortization </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="hdsn_DebtInstrumentLastTwelveMonthsAdjustedEarningsBeforeInterestTaxDepreciationAndAmortization_lbl" xml:lang="en-US"> Last twelve months adjusted earnings before interest, tax, depreciation and amortization </label>
<loc xlink:type="locator" xlink:href="hdsn-20201231.xsd#hdsn_DebtInstrumentAmendmentFeePercent" xlink:label="hdsn_DebtInstrumentAmendmentFeePercent"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="hdsn_DebtInstrumentAmendmentFeePercent" xlink:to="hdsn_DebtInstrumentAmendmentFeePercent_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:label="hdsn_DebtInstrumentAmendmentFeePercent_lbl" xml:lang="en-US"> Percent of the fee as closing conditions to the execution and delivery of the amendment. </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="hdsn_DebtInstrumentAmendmentFeePercent_lbl" xml:lang="en-US"> Debt Instrument, Amendment Fee, Percent </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="hdsn_DebtInstrumentAmendmentFeePercent_lbl" xml:lang="en-US"> Amendment fee (as a percent) </label>
<loc xlink:type="locator" xlink:href="hdsn-20201231.xsd#hdsn_DebtInstrumentThresholdPeriodAfterTriggerEventEntityShallCommenceTransaction" xlink:label="hdsn_DebtInstrumentThresholdPeriodAfterTriggerEventEntityShallCommenceTransaction"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="hdsn_DebtInstrumentThresholdPeriodAfterTriggerEventEntityShallCommenceTransaction" xlink:to="hdsn_DebtInstrumentThresholdPeriodAfterTriggerEventEntityShallCommenceTransaction_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:label="hdsn_DebtInstrumentThresholdPeriodAfterTriggerEventEntityShallCommenceTransaction_lbl" xml:lang="en-US"> Represents the threshold period after trigger event the entity shall commence transaction. </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="hdsn_DebtInstrumentThresholdPeriodAfterTriggerEventEntityShallCommenceTransaction_lbl" xml:lang="en-US"> Debt Instrument, Threshold Period After Trigger Event the Entity Shall Commence Transaction </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="hdsn_DebtInstrumentThresholdPeriodAfterTriggerEventEntityShallCommenceTransaction_lbl" xml:lang="en-US"> Threshold period after trigger event the entity shall commence transaction </label>
<loc xlink:type="locator" xlink:href="hdsn-20201231.xsd#hdsn_DebtInstrumentThresholdPeriodAfterTriggerEventEntityShallConsummateTransaction" xlink:label="hdsn_DebtInstrumentThresholdPeriodAfterTriggerEventEntityShallConsummateTransaction"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="hdsn_DebtInstrumentThresholdPeriodAfterTriggerEventEntityShallConsummateTransaction" xlink:to="hdsn_DebtInstrumentThresholdPeriodAfterTriggerEventEntityShallConsummateTransaction_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:label="hdsn_DebtInstrumentThresholdPeriodAfterTriggerEventEntityShallConsummateTransaction_lbl" xml:lang="en-US"> Represents the threshold period after trigger event the entity shall consummate transaction. </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="hdsn_DebtInstrumentThresholdPeriodAfterTriggerEventEntityShallConsummateTransaction_lbl" xml:lang="en-US"> Debt Instrument, Threshold Period After Trigger Event the Entity Shall Consummate Transaction </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="hdsn_DebtInstrumentThresholdPeriodAfterTriggerEventEntityShallConsummateTransaction_lbl" xml:lang="en-US"> Threshold period after trigger event the entity shall consummate transaction </label>
<loc xlink:type="locator" xlink:href="hdsn-20201231.xsd#hdsn_DeferredFinancingCosts" xlink:label="hdsn_DeferredFinancingCosts"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="hdsn_DeferredFinancingCosts" xlink:to="hdsn_DeferredFinancingCosts_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:label="hdsn_DeferredFinancingCosts_lbl" xml:lang="en-US"> Represents the information pertaining to deferred financing costs. </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="hdsn_DeferredFinancingCosts_lbl" xml:lang="en-US"> Deferred Financing Costs </label>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_UnsecuredDebt" xlink:label="us-gaap_UnsecuredDebt"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_UnsecuredDebt" xlink:to="us-gaap_UnsecuredDebt_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_UnsecuredDebt_lbl" xml:lang="en-US"> Unsecured Debt </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_UnsecuredDebt_lbl" xml:lang="en-US"> Unsecured loan </label>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_LongTermDebtTerm" xlink:label="us-gaap_LongTermDebtTerm"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_LongTermDebtTerm" xlink:to="us-gaap_LongTermDebtTerm_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_LongTermDebtTerm_lbl" xml:lang="en-US"> Long-term Debt, Term </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_LongTermDebtTerm_lbl" xml:lang="en-US"> Term of unforgiven loan </label>
<loc xlink:type="locator" xlink:href="hdsn-20201231.xsd#hdsn_DebtInstrumentInterestDeferralTerm" xlink:label="hdsn_DebtInstrumentInterestDeferralTerm"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="hdsn_DebtInstrumentInterestDeferralTerm" xlink:to="hdsn_DebtInstrumentInterestDeferralTerm_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:label="hdsn_DebtInstrumentInterestDeferralTerm_lbl" xml:lang="en-US"> The information pertaining to period for which interest can be deferred for unforgiven loan under paycheck protection program. </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="hdsn_DebtInstrumentInterestDeferralTerm_lbl" xml:lang="en-US"> Debt Instrument , Interest Deferral Term </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="hdsn_DebtInstrumentInterestDeferralTerm_lbl" xml:lang="en-US"> Deferral term of unforgiven loan </label>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_LineOfCreditFacilityExpirationPeriod" xlink:label="us-gaap_LineOfCreditFacilityExpirationPeriod"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_LineOfCreditFacilityExpirationPeriod" xlink:to="us-gaap_LineOfCreditFacilityExpirationPeriod_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_LineOfCreditFacilityExpirationPeriod_lbl" xml:lang="en-US"> Line of Credit Facility, Expiration Period </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_LineOfCreditFacilityExpirationPeriod_lbl" xml:lang="en-US"> Line of Credit Facility, Expiration Period </label>
<loc xlink:type="locator" xlink:href="hdsn-20201231.xsd#hdsn_NumberOfIndependentDirectorsToBeAppointedByTermLoanLenders" xlink:label="hdsn_NumberOfIndependentDirectorsToBeAppointedByTermLoanLenders"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="hdsn_NumberOfIndependentDirectorsToBeAppointedByTermLoanLenders" xlink:to="hdsn_NumberOfIndependentDirectorsToBeAppointedByTermLoanLenders_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:label="hdsn_NumberOfIndependentDirectorsToBeAppointedByTermLoanLenders_lbl" xml:lang="en-US"> Represents the number of independent directors to be appointed by term loan lenders. </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="hdsn_NumberOfIndependentDirectorsToBeAppointedByTermLoanLenders_lbl" xml:lang="en-US"> Number of Independent Directors to be Appointed by Term Loan Lenders </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="hdsn_NumberOfIndependentDirectorsToBeAppointedByTermLoanLenders_lbl" xml:lang="en-US"> Number of independent directors to be appointed by term loan lenders </label>
<loc xlink:type="locator" xlink:href="hdsn-20201231.xsd#hdsn_MinimumAggregateUndrawnAvailabilityExcessCashFlowCalculationAmount" xlink:label="hdsn_MinimumAggregateUndrawnAvailabilityExcessCashFlowCalculationAmount"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="hdsn_MinimumAggregateUndrawnAvailabilityExcessCashFlowCalculationAmount" xlink:to="hdsn_MinimumAggregateUndrawnAvailabilityExcessCashFlowCalculationAmount_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:label="hdsn_MinimumAggregateUndrawnAvailabilityExcessCashFlowCalculationAmount_lbl" xml:lang="en-US"> The minimum aggregate undrawn term loan availability used to determine percentage of excess cash flow to be used to paydown the loan. </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="hdsn_MinimumAggregateUndrawnAvailabilityExcessCashFlowCalculationAmount_lbl" xml:lang="en-US"> Minimum Aggregate Undrawn Availability Excess Cash Flow Calculation Amount </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="hdsn_MinimumAggregateUndrawnAvailabilityExcessCashFlowCalculationAmount_lbl" xml:lang="en-US"> Minimum Aggregate Undrawn Availability Excess Cash Flow Calculation </label>
<loc xlink:type="locator" xlink:href="hdsn-20201231.xsd#hdsn_RentExpenseLineItems" xlink:label="hdsn_RentExpenseLineItems"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="hdsn_RentExpenseLineItems" xlink:to="hdsn_RentExpenseLineItems_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="hdsn_RentExpenseLineItems_lbl" xml:lang="en-US"> Rent Expense [Line Items] </label>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_OperatingLeasesRentExpenseNet" xlink:label="us-gaap_OperatingLeasesRentExpenseNet"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_OperatingLeasesRentExpenseNet" xlink:to="us-gaap_OperatingLeasesRentExpenseNet_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_OperatingLeasesRentExpenseNet_lbl" xml:lang="en-US"> Operating Leases, Rent Expense, Net </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/verboseLabel" xlink:label="us-gaap_OperatingLeasesRentExpenseNet_lbl" xml:lang="en-US"> Rent expense </label>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_LeaseExpirationDate1" xlink:label="us-gaap_LeaseExpirationDate1"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_LeaseExpirationDate1" xlink:to="us-gaap_LeaseExpirationDate1_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_LeaseExpirationDate1_lbl" xml:lang="en-US"> Lease Expiration Date </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/verboseLabel" xlink:label="us-gaap_LeaseExpirationDate1_lbl" xml:lang="en-US"> Lease Expiration Date </label>
<loc xlink:type="locator" xlink:href="hdsn-20201231.xsd#hdsn_LeaseExpirationPeriodDescription" xlink:label="hdsn_LeaseExpirationPeriodDescription"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="hdsn_LeaseExpirationPeriodDescription" xlink:to="hdsn_LeaseExpirationPeriodDescription_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:label="hdsn_LeaseExpirationPeriodDescription_lbl" xml:lang="en-US"> Lease expiration period description. </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="hdsn_LeaseExpirationPeriodDescription_lbl" xml:lang="en-US"> Lease Expiration Period Description </label>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_LeaseAndRentalExpense" xlink:label="us-gaap_LeaseAndRentalExpense"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_LeaseAndRentalExpense" xlink:to="us-gaap_LeaseAndRentalExpense_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_LeaseAndRentalExpense_lbl" xml:lang="en-US"> Operating Leases, Rent Expense </label>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ScheduleOfEmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsTable" xlink:label="us-gaap_ScheduleOfEmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsTable"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_ScheduleOfEmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsTable" xlink:to="us-gaap_ScheduleOfEmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsTable_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_ScheduleOfEmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsTable_lbl" xml:lang="en-US"> Schedule of Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Table] </label>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_EmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsLineItems" xlink:label="us-gaap_EmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsLineItems"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_EmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsLineItems" xlink:to="us-gaap_EmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsLineItems_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_EmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsLineItems_lbl" xml:lang="en-US"> Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items] </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_EmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsLineItems_lbl" xml:lang="en-US"> Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items] </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/verboseLabel" xlink:label="us-gaap_EmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsLineItems_lbl" xml:lang="en-US"> Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items] </label>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedDividendRate" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedDividendRate"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedDividendRate" xlink:to="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedDividendRate_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedDividendRate_lbl" xml:lang="en-US"> Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Expected Dividend Rate </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/verboseLabel" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedDividendRate_lbl" xml:lang="en-US"> Dividend yield </label>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRate" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRate"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRate" xlink:to="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRate_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRate_lbl" xml:lang="en-US"> Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Risk Free Interest Rate </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRate_lbl" xml:lang="en-US"> Risk free interest rate </label>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedVolatilityRate" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedVolatilityRate"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedVolatilityRate" xlink:to="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedVolatilityRate_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedVolatilityRate_lbl" xml:lang="en-US"> Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Expected Volatility Rate </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedVolatilityRate_lbl" xml:lang="en-US"> Expected volatility </label>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardFairValueAssumptionsExpectedTerm1" xlink:label="us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardFairValueAssumptionsExpectedTerm1"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardFairValueAssumptionsExpectedTerm1" xlink:to="us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardFairValueAssumptionsExpectedTerm1_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardFairValueAssumptionsExpectedTerm1_lbl" xml:lang="en-US"> Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Expected Term </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/verboseLabel" xlink:label="us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardFairValueAssumptionsExpectedTerm1_lbl" xml:lang="en-US"> Expected lives </label>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingRollForward" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingRollForward"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingRollForward" xlink:to="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingRollForward_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/definitionGuidance" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingRollForward_lbl" xml:lang="en-US"> Number of Options </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingRollForward_lbl" xml:lang="en-US"> Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding [Roll Forward] </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/verboseLabel" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingRollForward_lbl" xml:lang="en-US"> Shares </label>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumber" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumber"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumber" xlink:to="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumber_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumber_lbl" xml:lang="en-US"> Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Number </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/periodEndLabel" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumber_lbl" xml:lang="en-US"> Outstanding at end of period </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/periodStartLabel" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumber_lbl" xml:lang="en-US"> Outstanding at beginning of period </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/verboseLabel" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumber_lbl" xml:lang="en-US"> Options outstanding </label>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsForfeituresInPeriod" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsForfeituresInPeriod"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsForfeituresInPeriod" xlink:to="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsForfeituresInPeriod_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsForfeituresInPeriod_lbl" xml:lang="en-US"> Share-based Compensation Arrangement by Share-based Payment Award, Options, Forfeitures in Period </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2009/role/negatedLabel" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsForfeituresInPeriod_lbl" xml:lang="en-US"> -Cancelled </label>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriod" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriod"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriod" xlink:to="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriod_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriod_lbl" xml:lang="en-US"> Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period, Net of Forfeitures </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriod_lbl" xml:lang="en-US"> -Granted </label>
<loc xlink:type="locator" xlink:href="hdsn-20201231.xsd#hdsn_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePriceAbstract" xlink:label="hdsn_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePriceAbstract"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="hdsn_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePriceAbstract" xlink:to="hdsn_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePriceAbstract_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="hdsn_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePriceAbstract_lbl" xml:lang="en-US"> Share Based Compensation Arrangement By Share Based Payment Award Options Outstanding Weighted Average Exercise Price [Abstract] </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/verboseLabel" xlink:label="hdsn_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePriceAbstract_lbl" xml:lang="en-US"> Weighted Average Exercise Price </label>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePrice" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePrice"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePrice" xlink:to="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePrice_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePrice_lbl" xml:lang="en-US"> Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Exercise Price </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/periodEndLabel" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePrice_lbl" xml:lang="en-US"> Outstanding at end of period </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/periodStartLabel" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePrice_lbl" xml:lang="en-US"> Outstanding at beginning of period </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePrice_lbl" xml:lang="en-US"> Options outstanding </label>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsForfeituresInPeriodWeightedAverageExercisePrice" xlink:label="us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsForfeituresInPeriodWeightedAverageExercisePrice"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsForfeituresInPeriodWeightedAverageExercisePrice" xlink:to="us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsForfeituresInPeriodWeightedAverageExercisePrice_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsForfeituresInPeriodWeightedAverageExercisePrice_lbl" xml:lang="en-US"> Share-based Compensation Arrangements by Share-based Payment Award, Options, Forfeitures in Period, Weighted Average Exercise Price </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsForfeituresInPeriodWeightedAverageExercisePrice_lbl" xml:lang="en-US"> -Cancelled </label>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsExercisesInPeriodWeightedAverageExercisePrice" xlink:label="us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsExercisesInPeriodWeightedAverageExercisePrice"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsExercisesInPeriodWeightedAverageExercisePrice" xlink:to="us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsExercisesInPeriodWeightedAverageExercisePrice_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsExercisesInPeriodWeightedAverageExercisePrice_lbl" xml:lang="en-US"> Share Based Compensation Arrangements By Share Based Payment Award Options Exercises In Period Weighted Average Exercise Price </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsExercisesInPeriodWeightedAverageExercisePrice_lbl" xml:lang="en-US"> -Exercised </label>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageGrantDateFairValue" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageGrantDateFairValue"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageGrantDateFairValue" xlink:to="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageGrantDateFairValue_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageGrantDateFairValue_lbl" xml:lang="en-US"> Share-Based Compensation Arrangement By Share-Based Payment Award, Options, Grants In Period, Weighted Average Grant Date Fair Value </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageGrantDateFairValue_lbl" xml:lang="en-US"> -Granted </label>
<loc xlink:type="locator" xlink:href="hdsn-20201231.xsd#hdsn_DisclosureWeightedAverageContractualLifeAndExercisePriceAbstract" xlink:label="hdsn_DisclosureWeightedAverageContractualLifeAndExercisePriceAbstract"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="hdsn_DisclosureWeightedAverageContractualLifeAndExercisePriceAbstract" xlink:to="hdsn_DisclosureWeightedAverageContractualLifeAndExercisePriceAbstract_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:label="hdsn_DisclosureWeightedAverageContractualLifeAndExercisePriceAbstract_lbl" xml:lang="en-US"> Disclosure - Weighted Average Contractual Life and Exercise Price [Abstract] </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="hdsn_DisclosureWeightedAverageContractualLifeAndExercisePriceAbstract_lbl" xml:lang="en-US"> Disclosure Weighted Average Contractual Life and Exercise Price [Abstract] </label>
<loc xlink:type="locator" xlink:href="hdsn-20201231.xsd#hdsn_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardPerformanceOptionsTable" xlink:label="hdsn_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardPerformanceOptionsTable"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="hdsn_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardPerformanceOptionsTable" xlink:to="hdsn_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardPerformanceOptionsTable_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:label="hdsn_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardPerformanceOptionsTable_lbl" xml:lang="en-US"> Schedule of Share based Compensation Arrangements by Share based Payment Award, Performance Options [Table] </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="hdsn_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardPerformanceOptionsTable_lbl" xml:lang="en-US"> Schedule Of Share Based Compensation Arrangements By Share Based Payment Award Performance Options [Table] </label>
<loc xlink:type="locator" xlink:href="hdsn-20201231.xsd#hdsn_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardPerformanceOptionsLineItems" xlink:label="hdsn_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardPerformanceOptionsLineItems"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="hdsn_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardPerformanceOptionsLineItems" xlink:to="hdsn_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardPerformanceOptionsLineItems_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:label="hdsn_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardPerformanceOptionsLineItems_lbl" xml:lang="en-US"> Schedule of Share based Compensation Arrangements by Share based Payment Award, Performance Options [Line Items] </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="hdsn_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardPerformanceOptionsLineItems_lbl" xml:lang="en-US"> Schedule Of Share Based Compensation Arrangements By Share Based Payment Award Performance Options [Line Items] </label>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsVestedNumberOfShares" xlink:label="us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsVestedNumberOfShares"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsVestedNumberOfShares" xlink:to="us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsVestedNumberOfShares_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsVestedNumberOfShares_lbl" xml:lang="en-US"> Share-based Compensation Arrangement by Share-based Payment Award, Options, Vested, Number of Shares </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/verboseLabel" xlink:label="us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsVestedNumberOfShares_lbl" xml:lang="en-US"> Options vested </label>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsNonvestedNumberOfShares" xlink:label="us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsNonvestedNumberOfShares"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsNonvestedNumberOfShares" xlink:to="us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsNonvestedNumberOfShares_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsNonvestedNumberOfShares_lbl" xml:lang="en-US"> Share-based Compensation Arrangement by Share-based Payment Award, Options, Nonvested, Number of Shares </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/verboseLabel" xlink:label="us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsNonvestedNumberOfShares_lbl" xml:lang="en-US"> Options unvested </label>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsAdditionalDisclosuresAbstract" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsAdditionalDisclosuresAbstract"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsAdditionalDisclosuresAbstract" xlink:to="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsAdditionalDisclosuresAbstract_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsAdditionalDisclosuresAbstract_lbl" xml:lang="en-US"> Share-based Compensation Arrangement by Share-based Payment Award, Options, Additional Disclosures [Abstract] </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/verboseLabel" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsAdditionalDisclosuresAbstract_lbl" xml:lang="en-US"> Weighted Average Remaining Contractual Life </label>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsOutstandingWeightedAverageRemainingContractualTerm2" xlink:label="us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsOutstandingWeightedAverageRemainingContractualTerm2"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsOutstandingWeightedAverageRemainingContractualTerm2" xlink:to="us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsOutstandingWeightedAverageRemainingContractualTerm2_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsOutstandingWeightedAverageRemainingContractualTerm2_lbl" xml:lang="en-US"> Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Remaining Contractual Term </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/verboseLabel" xlink:label="us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsOutstandingWeightedAverageRemainingContractualTerm2_lbl" xml:lang="en-US"> Options outstanding </label>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsVestedAndExpectedToVestOutstandingWeightedAverageRemainingContractualTerm1" xlink:label="us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsVestedAndExpectedToVestOutstandingWeightedAverageRemainingContractualTerm1"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsVestedAndExpectedToVestOutstandingWeightedAverageRemainingContractualTerm1" xlink:to="us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsVestedAndExpectedToVestOutstandingWeightedAverageRemainingContractualTerm1_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsVestedAndExpectedToVestOutstandingWeightedAverageRemainingContractualTerm1_lbl" xml:lang="en-US"> Share-based Compensation Arrangement by Share-based Payment Award, Options, Vested and Expected to Vest, Outstanding, Weighted Average Remaining Contractual Term </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/verboseLabel" xlink:label="us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsVestedAndExpectedToVestOutstandingWeightedAverageRemainingContractualTerm1_lbl" xml:lang="en-US"> Options vested </label>
<loc xlink:type="locator" xlink:href="hdsn-20201231.xsd#hdsn_ShareBasedCompensationArrangementBySharebasedPaymentAwardOptionsNonVestedOutstandingWeightedAverageRemainingContractualTerms" xlink:label="hdsn_ShareBasedCompensationArrangementBySharebasedPaymentAwardOptionsNonVestedOutstandingWeightedAverageRemainingContractualTerms"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="hdsn_ShareBasedCompensationArrangementBySharebasedPaymentAwardOptionsNonVestedOutstandingWeightedAverageRemainingContractualTerms" xlink:to="hdsn_ShareBasedCompensationArrangementBySharebasedPaymentAwardOptionsNonVestedOutstandingWeightedAverageRemainingContractualTerms_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:label="hdsn_ShareBasedCompensationArrangementBySharebasedPaymentAwardOptionsNonVestedOutstandingWeightedAverageRemainingContractualTerms_lbl" xml:lang="en-US"> Weighted average remaining contractual term for equity-based awards nonvested options in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days. </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="hdsn_ShareBasedCompensationArrangementBySharebasedPaymentAwardOptionsNonVestedOutstandingWeightedAverageRemainingContractualTerms_lbl" xml:lang="en-US"> Share based Compensation Arrangement By Sharebased Payment Award Options Non Vested Outstanding Weighted Average Remaining Contractual Terms </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="hdsn_ShareBasedCompensationArrangementBySharebasedPaymentAwardOptionsNonVestedOutstandingWeightedAverageRemainingContractualTerms_lbl" xml:lang="en-US"> Options unvested </label>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePriceRollforward" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePriceRollforward"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePriceRollforward" xlink:to="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePriceRollforward_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePriceRollforward_lbl" xml:lang="en-US"> Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Exercise Price [Abstract] </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/verboseLabel" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePriceRollforward_lbl" xml:lang="en-US"> Weighted Average Exercise Price </label>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedAndExpectedToVestOutstandingWeightedAverageExercisePrice" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedAndExpectedToVestOutstandingWeightedAverageExercisePrice"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedAndExpectedToVestOutstandingWeightedAverageExercisePrice" xlink:to="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedAndExpectedToVestOutstandingWeightedAverageExercisePrice_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedAndExpectedToVestOutstandingWeightedAverageExercisePrice_lbl" xml:lang="en-US"> Share-based Compensation Arrangement by Share-based Payment Award, Options, Vested and Expected to Vest, Outstanding, Weighted Average Exercise Price </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedAndExpectedToVestOutstandingWeightedAverageExercisePrice_lbl" xml:lang="en-US"> Options vested </label>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsNonvestedWeightedAverageGrantDateFairValue" xlink:label="us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsNonvestedWeightedAverageGrantDateFairValue"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsNonvestedWeightedAverageGrantDateFairValue" xlink:to="us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsNonvestedWeightedAverageGrantDateFairValue_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsNonvestedWeightedAverageGrantDateFairValue_lbl" xml:lang="en-US"> Share-based Compensation Arrangement by Share-based Payment Award, Option, Nonvested, Weighted Average Exercise Price </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/verboseLabel" xlink:label="us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsNonvestedWeightedAverageGrantDateFairValue_lbl" xml:lang="en-US"> Options unvested </label>
<loc xlink:type="locator" xlink:href="hdsn-20201231.xsd#hdsn_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedInPeriodTotalIntrinsicValue" xlink:label="hdsn_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedInPeriodTotalIntrinsicValue"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="hdsn_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedInPeriodTotalIntrinsicValue" xlink:to="hdsn_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedInPeriodTotalIntrinsicValue_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:label="hdsn_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedInPeriodTotalIntrinsicValue_lbl" xml:lang="en-US"> Share Based Compensation Arrangement by Share Based Payment Award, Options, Vested in Period, Total Intrinsic Value </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="hdsn_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedInPeriodTotalIntrinsicValue_lbl" xml:lang="en-US"> Share Based Compensation Arrangement By Share Based Payment Award Options Vested In Period Total Intrinsic Value </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/verboseLabel" xlink:label="hdsn_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedInPeriodTotalIntrinsicValue_lbl" xml:lang="en-US"> Intrinsic value of options vested </label>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisesInPeriodTotalIntrinsicValue" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisesInPeriodTotalIntrinsicValue"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisesInPeriodTotalIntrinsicValue" xlink:to="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisesInPeriodTotalIntrinsicValue_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisesInPeriodTotalIntrinsicValue_lbl" xml:lang="en-US"> Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercises in Period, Intrinsic Value </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/verboseLabel" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisesInPeriodTotalIntrinsicValue_lbl" xml:lang="en-US"> Intrinsic value of options exercised </label>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_AllocatedShareBasedCompensationExpense" xlink:label="us-gaap_AllocatedShareBasedCompensationExpense"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_AllocatedShareBasedCompensationExpense" xlink:to="us-gaap_AllocatedShareBasedCompensationExpense_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_AllocatedShareBasedCompensationExpense_lbl" xml:lang="en-US"> Allocated Share Based Compensation Expense </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_AllocatedShareBasedCompensationExpense_lbl" xml:lang="en-US"> Share based compensation expense </label>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DeferredCompensationArrangementWithIndividualCommonStockReservedForFutureIssuance" xlink:label="us-gaap_DeferredCompensationArrangementWithIndividualCommonStockReservedForFutureIssuance"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_DeferredCompensationArrangementWithIndividualCommonStockReservedForFutureIssuance" xlink:to="us-gaap_DeferredCompensationArrangementWithIndividualCommonStockReservedForFutureIssuance_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_DeferredCompensationArrangementWithIndividualCommonStockReservedForFutureIssuance_lbl" xml:lang="en-US"> Deferred Compensation Arrangement With Individual Common Stock Reserved For Future Issuance </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_DeferredCompensationArrangementWithIndividualCommonStockReservedForFutureIssuance_lbl" xml:lang="en-US"> Common stock reserved for issuance </label>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardAwardVestingPeriod1" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardAwardVestingPeriod1"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardAwardVestingPeriod1" xlink:to="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardAwardVestingPeriod1_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardAwardVestingPeriod1_lbl" xml:lang="en-US"> Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Period </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardAwardVestingPeriod1_lbl" xml:lang="en-US"> Stock option vesting period </label>
<loc xlink:type="locator" xlink:href="hdsn-20201231.xsd#hdsn_ShareBasedCompensationArrangementByShareBasedPaymentAwardPercentageFromFairMarketPrice" xlink:label="hdsn_ShareBasedCompensationArrangementByShareBasedPaymentAwardPercentageFromFairMarketPrice"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="hdsn_ShareBasedCompensationArrangementByShareBasedPaymentAwardPercentageFromFairMarketPrice" xlink:to="hdsn_ShareBasedCompensationArrangementByShareBasedPaymentAwardPercentageFromFairMarketPrice_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:label="hdsn_ShareBasedCompensationArrangementByShareBasedPaymentAwardPercentageFromFairMarketPrice_lbl" xml:lang="en-US"> Share based compensation arrangement by share based payment award percentage from fair market price. </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="hdsn_ShareBasedCompensationArrangementByShareBasedPaymentAwardPercentageFromFairMarketPrice_lbl" xml:lang="en-US"> Share based Compensation Arrangement By Share Based Payment Award Percentage From Fair Market Price </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/verboseLabel" xlink:label="hdsn_ShareBasedCompensationArrangementByShareBasedPaymentAwardPercentageFromFairMarketPrice_lbl" xml:lang="en-US"> Share-based compensation arrangement by share based payment award percentage of fair market Person holding more then 10% voting stock </label>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodGross" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodGross"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodGross" xlink:to="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodGross_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodGross_lbl" xml:lang="en-US"> Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period, Gross </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodGross_lbl" xml:lang="en-US"> Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period, Gross </label>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedAndExpectedToVestOutstandingNumber" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedAndExpectedToVestOutstandingNumber"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedAndExpectedToVestOutstandingNumber" xlink:to="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedAndExpectedToVestOutstandingNumber_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedAndExpectedToVestOutstandingNumber_lbl" xml:lang="en-US"> Share-based Compensation Arrangement by Share-based Payment Award, Options, Vested and Expected to Vest, Outstanding, Number </label>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingIntrinsicValue" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingIntrinsicValue"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingIntrinsicValue" xlink:to="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingIntrinsicValue_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingIntrinsicValue_lbl" xml:lang="en-US"> Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Intrinsic Value </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingIntrinsicValue_lbl" xml:lang="en-US"> Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Intrinsic Value </label>
<loc xlink:type="locator" xlink:href="hdsn-20201231.xsd#hdsn_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsAggregateIntrinsicValueNonvested" xlink:label="hdsn_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsAggregateIntrinsicValueNonvested"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="hdsn_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsAggregateIntrinsicValueNonvested" xlink:to="hdsn_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsAggregateIntrinsicValueNonvested_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:label="hdsn_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsAggregateIntrinsicValueNonvested_lbl" xml:lang="en-US"> Intrinsic value of equity-based compensation awards not vested. Stock units </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="hdsn_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsAggregateIntrinsicValueNonvested_lbl" xml:lang="en-US"> Share-based Compensation Arrangement by Share-based Payment Award, Options, Aggregate Intrinsic Value, Nonvested </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="hdsn_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsAggregateIntrinsicValueNonvested_lbl" xml:lang="en-US"> Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Intrinsic Value </label>
<loc xlink:type="locator" xlink:href="hdsn-20201231.xsd#hdsn_CashReceivedFromSettlementOfWorkingCapitalAdjustmentDispute" xlink:label="hdsn_CashReceivedFromSettlementOfWorkingCapitalAdjustmentDispute"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="hdsn_CashReceivedFromSettlementOfWorkingCapitalAdjustmentDispute" xlink:to="hdsn_CashReceivedFromSettlementOfWorkingCapitalAdjustmentDispute_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:label="hdsn_CashReceivedFromSettlementOfWorkingCapitalAdjustmentDispute_lbl" xml:lang="en-US"> The amount of cash received from settlement of a working capital adjustment dispute, classified as other income. </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="hdsn_CashReceivedFromSettlementOfWorkingCapitalAdjustmentDispute_lbl" xml:lang="en-US"> Cash received from settlement of a working capital adjustment dispute </label>
<loc xlink:type="locator" xlink:href="hdsn-20201231.xsd#hdsn_OtherIncomeRelatingToChangeInEstimateOfItsCylinderDepositLiabilityAccount" xlink:label="hdsn_OtherIncomeRelatingToChangeInEstimateOfItsCylinderDepositLiabilityAccount"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="hdsn_OtherIncomeRelatingToChangeInEstimateOfItsCylinderDepositLiabilityAccount" xlink:to="hdsn_OtherIncomeRelatingToChangeInEstimateOfItsCylinderDepositLiabilityAccount_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:label="hdsn_OtherIncomeRelatingToChangeInEstimateOfItsCylinderDepositLiabilityAccount_lbl" xml:lang="en-US"> The income relating to a change in estimate of its cylinder deposit liability account, classified as other income. </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="hdsn_OtherIncomeRelatingToChangeInEstimateOfItsCylinderDepositLiabilityAccount_lbl" xml:lang="en-US"> Other income relating to a change in estimate of its cylinder deposit liability account </label>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ScheduleOfRelatedPartyTransactionsByRelatedPartyTable" xlink:label="us-gaap_ScheduleOfRelatedPartyTransactionsByRelatedPartyTable"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_ScheduleOfRelatedPartyTransactionsByRelatedPartyTable" xlink:to="us-gaap_ScheduleOfRelatedPartyTransactionsByRelatedPartyTable_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_ScheduleOfRelatedPartyTransactionsByRelatedPartyTable_lbl" xml:lang="en-US"> Schedule of Related Party Transactions, by Related Party [Table] </label>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_RelatedPartyTransactionLineItems" xlink:label="us-gaap_RelatedPartyTransactionLineItems"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_RelatedPartyTransactionLineItems" xlink:to="us-gaap_RelatedPartyTransactionLineItems_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_RelatedPartyTransactionLineItems_lbl" xml:lang="en-US"> Related Party Transaction [Line Items] </label>
<loc xlink:type="locator" xlink:href="hdsn-20201231.xsd#hdsn_MonthlyConsultingFee" xlink:label="hdsn_MonthlyConsultingFee"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="hdsn_MonthlyConsultingFee" xlink:to="hdsn_MonthlyConsultingFee_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:label="hdsn_MonthlyConsultingFee_lbl" xml:lang="en-US"> Amount the company pays as a consulting fee. </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="hdsn_MonthlyConsultingFee_lbl" xml:lang="en-US"> Monthly Consulting Fee </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="hdsn_MonthlyConsultingFee_lbl" xml:lang="en-US"> Monthly consulting fee </label>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DeferredCompensationArrangementWithIndividualCompensationExpense" xlink:label="us-gaap_DeferredCompensationArrangementWithIndividualCompensationExpense"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_DeferredCompensationArrangementWithIndividualCompensationExpense" xlink:to="us-gaap_DeferredCompensationArrangementWithIndividualCompensationExpense_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_DeferredCompensationArrangementWithIndividualCompensationExpense_lbl" xml:lang="en-US"> Deferred Compensation Arrangement with Individual, Compensation Expense </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_DeferredCompensationArrangementWithIndividualCompensationExpense_lbl" xml:lang="en-US"> Base salary </label>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DeferredCompensationArrangementWithIndividualSharesIssued" xlink:label="us-gaap_DeferredCompensationArrangementWithIndividualSharesIssued"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_DeferredCompensationArrangementWithIndividualSharesIssued" xlink:to="us-gaap_DeferredCompensationArrangementWithIndividualSharesIssued_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_DeferredCompensationArrangementWithIndividualSharesIssued_lbl" xml:lang="en-US"> Deferred Compensation Arrangement with Individual, Shares Issued </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_DeferredCompensationArrangementWithIndividualSharesIssued_lbl" xml:lang="en-US"> Stock option to purchase </label>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DeferredCompensationArrangementWithIndividualExercisePrice" xlink:label="us-gaap_DeferredCompensationArrangementWithIndividualExercisePrice"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_DeferredCompensationArrangementWithIndividualExercisePrice" xlink:to="us-gaap_DeferredCompensationArrangementWithIndividualExercisePrice_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_DeferredCompensationArrangementWithIndividualExercisePrice_lbl" xml:lang="en-US"> Deferred Compensation Arrangement with Individual, Exercise Price </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_DeferredCompensationArrangementWithIndividualExercisePrice_lbl" xml:lang="en-US"> Common stock at an exercise price </label>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_StatementEquityComponentsAxis" xlink:label="us-gaap_StatementEquityComponentsAxis"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_StatementEquityComponentsAxis" xlink:to="us-gaap_StatementEquityComponentsAxis_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_StatementEquityComponentsAxis_lbl" xml:lang="en-US"> Equity Components [Axis] </label>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_EquityComponentDomain" xlink:label="us-gaap_EquityComponentDomain"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_EquityComponentDomain" xlink:to="us-gaap_EquityComponentDomain_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_EquityComponentDomain_lbl" xml:lang="en-US"> Equity Component [Domain] </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_EquityComponentDomain_lbl" xml:lang="en-US"> Equity Component [Domain] </label>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_CommonStockMember" xlink:label="us-gaap_CommonStockMember"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_CommonStockMember" xlink:to="us-gaap_CommonStockMember_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_CommonStockMember_lbl" xml:lang="en-US"> Common Stock [Member] </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_CommonStockMember_lbl" xml:lang="en-US"> Common Stock [Member] </label>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_AdditionalPaidInCapitalMember" xlink:label="us-gaap_AdditionalPaidInCapitalMember"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_AdditionalPaidInCapitalMember" xlink:to="us-gaap_AdditionalPaidInCapitalMember_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_AdditionalPaidInCapitalMember_lbl" xml:lang="en-US"> Additional Paid In Capital [Member] </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_AdditionalPaidInCapitalMember_lbl" xml:lang="en-US"> Additional Paid-in Capital [Member] </label>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_RetainedEarningsMember" xlink:label="us-gaap_RetainedEarningsMember"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_RetainedEarningsMember" xlink:to="us-gaap_RetainedEarningsMember_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_RetainedEarningsMember_lbl" xml:lang="en-US"> Retained Earnings [Member] </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_RetainedEarningsMember_lbl" xml:lang="en-US"> Retained Earnings (Accumulated Deficit) [Member] </label>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_UnusualOrInfrequentItemAxis" xlink:label="us-gaap_UnusualOrInfrequentItemAxis"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_UnusualOrInfrequentItemAxis" xlink:to="us-gaap_UnusualOrInfrequentItemAxis_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_UnusualOrInfrequentItemAxis_lbl" xml:lang="en-US"> Unusual or Infrequent Item, or Both [Axis] </label>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_UnusualOrInfrequentItemDomain" xlink:label="us-gaap_UnusualOrInfrequentItemDomain"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_UnusualOrInfrequentItemDomain" xlink:to="us-gaap_UnusualOrInfrequentItemDomain_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_UnusualOrInfrequentItemDomain_lbl" xml:lang="en-US"> Unusual Or Infrequent Item [Domain] </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_UnusualOrInfrequentItemDomain_lbl" xml:lang="en-US"> Unusual or Infrequent Item, or Both [Domain] </label>
<loc xlink:type="locator" xlink:href="hdsn-20201231.xsd#hdsn_CoronavirusAidReliefAndEconomicSecurityActMember" xlink:label="hdsn_CoronavirusAidReliefAndEconomicSecurityActMember"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="hdsn_CoronavirusAidReliefAndEconomicSecurityActMember" xlink:to="hdsn_CoronavirusAidReliefAndEconomicSecurityActMember_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:label="hdsn_CoronavirusAidReliefAndEconomicSecurityActMember_lbl" xml:lang="en-US"> Represents the information pertaining to CARES Act. </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="hdsn_CoronavirusAidReliefAndEconomicSecurityActMember_lbl" xml:lang="en-US"> Coronavirus Aid Relief And Economic Security Act [Member] </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="hdsn_CoronavirusAidReliefAndEconomicSecurityActMember_lbl" xml:lang="en-US"> CARES Act </label>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ConcentrationRiskByTypeAxis" xlink:label="us-gaap_ConcentrationRiskByTypeAxis"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_ConcentrationRiskByTypeAxis" xlink:to="us-gaap_ConcentrationRiskByTypeAxis_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_ConcentrationRiskByTypeAxis_lbl" xml:lang="en-US"> Concentration Risk Type [Axis] </label>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ConcentrationRiskTypeDomain" xlink:label="us-gaap_ConcentrationRiskTypeDomain"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_ConcentrationRiskTypeDomain" xlink:to="us-gaap_ConcentrationRiskTypeDomain_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_ConcentrationRiskTypeDomain_lbl" xml:lang="en-US"> Concentration Risk Type [Domain] </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_ConcentrationRiskTypeDomain_lbl" xml:lang="en-US"> Concentration Risk Type [Domain] </label>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_CustomerConcentrationRiskMember" xlink:label="us-gaap_CustomerConcentrationRiskMember"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_CustomerConcentrationRiskMember" xlink:to="us-gaap_CustomerConcentrationRiskMember_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_CustomerConcentrationRiskMember_lbl" xml:lang="en-US"> Customer Concentration Risk [Member] </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_CustomerConcentrationRiskMember_lbl" xml:lang="en-US"> Customer Concentration Risk [Member] </label>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_AdjustmentsForNewAccountingPronouncementsAxis" xlink:label="us-gaap_AdjustmentsForNewAccountingPronouncementsAxis"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_AdjustmentsForNewAccountingPronouncementsAxis" xlink:to="us-gaap_AdjustmentsForNewAccountingPronouncementsAxis_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_AdjustmentsForNewAccountingPronouncementsAxis_lbl" xml:lang="en-US"> Adjustments for New Accounting Pronouncements [Axis] </label>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_TypeOfAdoptionMember" xlink:label="us-gaap_TypeOfAdoptionMember"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_TypeOfAdoptionMember" xlink:to="us-gaap_TypeOfAdoptionMember_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_TypeOfAdoptionMember_lbl" xml:lang="en-US"> Type Of Adoption [Member] </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_TypeOfAdoptionMember_lbl" xml:lang="en-US"> Type of Adoption [Domain] </label>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_AccountingStandardsUpdate201602Member" xlink:label="us-gaap_AccountingStandardsUpdate201602Member"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_AccountingStandardsUpdate201602Member" xlink:to="us-gaap_AccountingStandardsUpdate201602Member_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_AccountingStandardsUpdate201602Member_lbl" xml:lang="en-US"> Accounting Standards Update201602 [Member] </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_AccountingStandardsUpdate201602Member_lbl" xml:lang="en-US"> ASU Topic 842 [Member] </label>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/srt/2020/elts/srt-2020-01-31.xsd#srt_MajorCustomersAxis" xlink:label="srt_MajorCustomersAxis"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="srt_MajorCustomersAxis" xlink:to="srt_MajorCustomersAxis_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="srt_MajorCustomersAxis_lbl" xml:lang="en-US"> Customer [Axis] </label>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/srt/2020/elts/srt-2020-01-31.xsd#srt_NameOfMajorCustomerDomain" xlink:label="srt_NameOfMajorCustomerDomain"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="srt_NameOfMajorCustomerDomain" xlink:to="srt_NameOfMajorCustomerDomain_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="srt_NameOfMajorCustomerDomain_lbl" xml:lang="en-US"> Name Of Major Customer [Domain] </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="srt_NameOfMajorCustomerDomain_lbl" xml:lang="en-US"> Customer [Domain] </label>
<loc xlink:type="locator" xlink:href="hdsn-20201231.xsd#hdsn_OneCustomerMember" xlink:label="hdsn_OneCustomerMember"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="hdsn_OneCustomerMember" xlink:to="hdsn_OneCustomerMember_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:label="hdsn_OneCustomerMember_lbl" xml:lang="en-US"> Pertains to one customer. </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="hdsn_OneCustomerMember_lbl" xml:lang="en-US"> One Customer [Member] </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="hdsn_OneCustomerMember_lbl" xml:lang="en-US"> One Customer </label>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ConcentrationRiskByBenchmarkAxis" xlink:label="us-gaap_ConcentrationRiskByBenchmarkAxis"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_ConcentrationRiskByBenchmarkAxis" xlink:to="us-gaap_ConcentrationRiskByBenchmarkAxis_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_ConcentrationRiskByBenchmarkAxis_lbl" xml:lang="en-US"> Concentration Risk Benchmark [Axis] </label>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ConcentrationRiskBenchmarkDomain" xlink:label="us-gaap_ConcentrationRiskBenchmarkDomain"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_ConcentrationRiskBenchmarkDomain" xlink:to="us-gaap_ConcentrationRiskBenchmarkDomain_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_ConcentrationRiskBenchmarkDomain_lbl" xml:lang="en-US"> Concentration Risk Benchmark [Domain] </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_ConcentrationRiskBenchmarkDomain_lbl" xml:lang="en-US"> Concentration Risk Benchmark [Domain] </label>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_RevenueFromContractWithCustomerMember" xlink:label="us-gaap_RevenueFromContractWithCustomerMember"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_RevenueFromContractWithCustomerMember" xlink:to="us-gaap_RevenueFromContractWithCustomerMember_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_RevenueFromContractWithCustomerMember_lbl" xml:lang="en-US"> Revenue From Contract With Customer [Member] </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_RevenueFromContractWithCustomerMember_lbl" xml:lang="en-US"> Revenue from Contract with Customer [Member] </label>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_AccountsReceivableMember" xlink:label="us-gaap_AccountsReceivableMember"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_AccountsReceivableMember" xlink:to="us-gaap_AccountsReceivableMember_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_AccountsReceivableMember_lbl" xml:lang="en-US"> Accounts Receivable [Member] </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_AccountsReceivableMember_lbl" xml:lang="en-US"> Accounts Receivable </label>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_IncomeTaxAuthorityAxis" xlink:label="us-gaap_IncomeTaxAuthorityAxis"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_IncomeTaxAuthorityAxis" xlink:to="us-gaap_IncomeTaxAuthorityAxis_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_IncomeTaxAuthorityAxis_lbl" xml:lang="en-US"> Income Tax Authority [Axis] </label>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_IncomeTaxAuthorityDomain" xlink:label="us-gaap_IncomeTaxAuthorityDomain"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_IncomeTaxAuthorityDomain" xlink:to="us-gaap_IncomeTaxAuthorityDomain_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_IncomeTaxAuthorityDomain_lbl" xml:lang="en-US"> Income Tax Authority [Domain] </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_IncomeTaxAuthorityDomain_lbl" xml:lang="en-US"> Income Tax Authority [Domain] </label>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_StateAndLocalJurisdictionMember" xlink:label="us-gaap_StateAndLocalJurisdictionMember"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_StateAndLocalJurisdictionMember" xlink:to="us-gaap_StateAndLocalJurisdictionMember_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_StateAndLocalJurisdictionMember_lbl" xml:lang="en-US"> State And Local Jurisdiction [Member] </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_StateAndLocalJurisdictionMember_lbl" xml:lang="en-US"> State and Local Jurisdiction [Member] </label>
<loc xlink:type="locator" xlink:href="hdsn-20201231.xsd#hdsn_ExpirationPeriodAxis" xlink:label="hdsn_ExpirationPeriodAxis"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="hdsn_ExpirationPeriodAxis" xlink:to="hdsn_ExpirationPeriodAxis_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="hdsn_ExpirationPeriodAxis_lbl" xml:lang="en-US"> Expiration Period [Axis] </label>
<loc xlink:type="locator" xlink:href="hdsn-20201231.xsd#hdsn_ExpirationPeriodDomain" xlink:label="hdsn_ExpirationPeriodDomain"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="hdsn_ExpirationPeriodDomain" xlink:to="hdsn_ExpirationPeriodDomain_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="hdsn_ExpirationPeriodDomain_lbl" xml:lang="en-US"> Expiration Period [Domain] </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="hdsn_ExpirationPeriodDomain_lbl" xml:lang="en-US"> Expiration Period [Domain] </label>
<loc xlink:type="locator" xlink:href="hdsn-20201231.xsd#hdsn_NoExpirationMember" xlink:label="hdsn_NoExpirationMember"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="hdsn_NoExpirationMember" xlink:to="hdsn_NoExpirationMember_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="hdsn_NoExpirationMember_lbl" xml:lang="en-US"> No Expiration [Member] </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="hdsn_NoExpirationMember_lbl" xml:lang="en-US"> No Expiration [Member] </label>
<loc xlink:type="locator" xlink:href="hdsn-20201231.xsd#hdsn_ExpiringThrough2023Member" xlink:label="hdsn_ExpiringThrough2023Member"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="hdsn_ExpiringThrough2023Member" xlink:to="hdsn_ExpiringThrough2023Member_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:label="hdsn_ExpiringThrough2023Member_lbl" xml:lang="en-US"> Represents the expiration period. </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="hdsn_ExpiringThrough2023Member_lbl" xml:lang="en-US"> Expiring Through2023 [Member] </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="hdsn_ExpiringThrough2023Member_lbl" xml:lang="en-US"> Expiring Through 2023 [Member] </label>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_IncomeStatementLocationAxis" xlink:label="us-gaap_IncomeStatementLocationAxis"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_IncomeStatementLocationAxis" xlink:to="us-gaap_IncomeStatementLocationAxis_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_IncomeStatementLocationAxis_lbl" xml:lang="en-US"> Income Statement Location [Axis] </label>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_IncomeStatementLocationDomain" xlink:label="us-gaap_IncomeStatementLocationDomain"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_IncomeStatementLocationDomain" xlink:to="us-gaap_IncomeStatementLocationDomain_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_IncomeStatementLocationDomain_lbl" xml:lang="en-US"> Income Statement Location [Domain] </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_IncomeStatementLocationDomain_lbl" xml:lang="en-US"> Income Statement Location [Domain] </label>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_SellingGeneralAndAdministrativeExpensesMember" xlink:label="us-gaap_SellingGeneralAndAdministrativeExpensesMember"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_SellingGeneralAndAdministrativeExpensesMember" xlink:to="us-gaap_SellingGeneralAndAdministrativeExpensesMember_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_SellingGeneralAndAdministrativeExpensesMember_lbl" xml:lang="en-US"> Selling General And Administrative Expenses [Member] </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_SellingGeneralAndAdministrativeExpensesMember_lbl" xml:lang="en-US"> Selling, General and Administrative Expenses [Member] </label>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_TypeOfArrangementAxis" xlink:label="us-gaap_TypeOfArrangementAxis"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_TypeOfArrangementAxis" xlink:to="us-gaap_TypeOfArrangementAxis_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_TypeOfArrangementAxis_lbl" xml:lang="en-US"> Collaborative Arrangement and Arrangement Other than Collaborative [Axis] </label>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ArrangementsAndNonarrangementTransactionsMember" xlink:label="us-gaap_ArrangementsAndNonarrangementTransactionsMember"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_ArrangementsAndNonarrangementTransactionsMember" xlink:to="us-gaap_ArrangementsAndNonarrangementTransactionsMember_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_ArrangementsAndNonarrangementTransactionsMember_lbl" xml:lang="en-US"> Arrangements And Nonarrangement Transactions [Member] </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_ArrangementsAndNonarrangementTransactionsMember_lbl" xml:lang="en-US"> Collaborative Arrangement and Arrangement Other than Collaborative [Domain] </label>
<loc xlink:type="locator" xlink:href="hdsn-20201231.xsd#hdsn_RevolverGuarantyAndSecurityAgreementMember" xlink:label="hdsn_RevolverGuarantyAndSecurityAgreementMember"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="hdsn_RevolverGuarantyAndSecurityAgreementMember" xlink:to="hdsn_RevolverGuarantyAndSecurityAgreementMember_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:label="hdsn_RevolverGuarantyAndSecurityAgreementMember_lbl" xml:lang="en-US"> n/a. </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="hdsn_RevolverGuarantyAndSecurityAgreementMember_lbl" xml:lang="en-US"> Revolver Guaranty And Security Agreement [Member] </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="hdsn_RevolverGuarantyAndSecurityAgreementMember_lbl" xml:lang="en-US"> Revolver Guaranty and Security Agreement </label>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_LineOfCreditFacilityAxis" xlink:label="us-gaap_LineOfCreditFacilityAxis"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_LineOfCreditFacilityAxis" xlink:to="us-gaap_LineOfCreditFacilityAxis_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_LineOfCreditFacilityAxis_lbl" xml:lang="en-US"> Lender Name [Axis] </label>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_LineOfCreditFacilityLenderDomain" xlink:label="us-gaap_LineOfCreditFacilityLenderDomain"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_LineOfCreditFacilityLenderDomain" xlink:to="us-gaap_LineOfCreditFacilityLenderDomain_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_LineOfCreditFacilityLenderDomain_lbl" xml:lang="en-US"> Line Of Credit Facility Lender [Domain] </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_LineOfCreditFacilityLenderDomain_lbl" xml:lang="en-US"> Line of Credit Facility, Lender [Domain] </label>
<loc xlink:type="locator" xlink:href="hdsn-20201231.xsd#hdsn_TermLoanMember" xlink:label="hdsn_TermLoanMember"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="hdsn_TermLoanMember" xlink:to="hdsn_TermLoanMember_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:label="hdsn_TermLoanMember_lbl" xml:lang="en-US"> Term Loan [Member] </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="hdsn_TermLoanMember_lbl" xml:lang="en-US"> Term Loan [Member] </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="hdsn_TermLoanMember_lbl" xml:lang="en-US"> Term Loan </label>
<loc xlink:type="locator" xlink:href="hdsn-20201231.xsd#hdsn_PncBankMember" xlink:label="hdsn_PncBankMember"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="hdsn_PncBankMember" xlink:to="hdsn_PncBankMember_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="hdsn_PncBankMember_lbl" xml:lang="en-US"> Pnc Bank [Member] </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="hdsn_PncBankMember_lbl" xml:lang="en-US"> PNC Bank [Member] </label>
<loc xlink:type="locator" xlink:href="hdsn-20201231.xsd#hdsn_DomesticRateLoansMember" xlink:label="hdsn_DomesticRateLoansMember"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="hdsn_DomesticRateLoansMember" xlink:to="hdsn_DomesticRateLoansMember_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:label="hdsn_DomesticRateLoansMember_lbl" xml:lang="en-US"> Pertains to domestic rate loans. </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="hdsn_DomesticRateLoansMember_lbl" xml:lang="en-US"> Domestic Rate Loans [Member] </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="hdsn_DomesticRateLoansMember_lbl" xml:lang="en-US"> Domestic Rate Loans [Member] </label>
<loc xlink:type="locator" xlink:href="hdsn-20201231.xsd#hdsn_EurodollarRateLoansMember" xlink:label="hdsn_EurodollarRateLoansMember"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="hdsn_EurodollarRateLoansMember" xlink:to="hdsn_EurodollarRateLoansMember_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:label="hdsn_EurodollarRateLoansMember_lbl" xml:lang="en-US"> Pertains to eurodollar rate loans. </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="hdsn_EurodollarRateLoansMember_lbl" xml:lang="en-US"> Eurodollar Rate Loans [Member] </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="hdsn_EurodollarRateLoansMember_lbl" xml:lang="en-US"> Eurodollar Rate Loans [Member] </label>
<loc xlink:type="locator" xlink:href="hdsn-20201231.xsd#hdsn_WellsFargoMember" xlink:label="hdsn_WellsFargoMember"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="hdsn_WellsFargoMember" xlink:to="hdsn_WellsFargoMember_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:label="hdsn_WellsFargoMember_lbl" xml:lang="en-US"> Represents the information pertaining to wells fargo. </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="hdsn_WellsFargoMember_lbl" xml:lang="en-US"> Wells Fargo [Member] </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="hdsn_WellsFargoMember_lbl" xml:lang="en-US"> Wells Fargo </label>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_CreditFacilityAxis" xlink:label="us-gaap_CreditFacilityAxis"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_CreditFacilityAxis" xlink:to="us-gaap_CreditFacilityAxis_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_CreditFacilityAxis_lbl" xml:lang="en-US"> Credit Facility [Axis] </label>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_CreditFacilityDomain" xlink:label="us-gaap_CreditFacilityDomain"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_CreditFacilityDomain" xlink:to="us-gaap_CreditFacilityDomain_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_CreditFacilityDomain_lbl" xml:lang="en-US"> Credit Facility [Domain] </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_CreditFacilityDomain_lbl" xml:lang="en-US"> Credit Facility [Domain] </label>
<loc xlink:type="locator" xlink:href="hdsn-20201231.xsd#hdsn_AmendedAndRestatedRevolvingCreditAndSecurityAgreementMember" xlink:label="hdsn_AmendedAndRestatedRevolvingCreditAndSecurityAgreementMember"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="hdsn_AmendedAndRestatedRevolvingCreditAndSecurityAgreementMember" xlink:to="hdsn_AmendedAndRestatedRevolvingCreditAndSecurityAgreementMember_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:label="hdsn_AmendedAndRestatedRevolvingCreditAndSecurityAgreementMember_lbl" xml:lang="en-US"> Information pertaining to the amended and restated revolving credit and security agreement. </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="hdsn_AmendedAndRestatedRevolvingCreditAndSecurityAgreementMember_lbl" xml:lang="en-US"> Amended And Restated Revolving Credit And Security Agreement [Member] </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="hdsn_AmendedAndRestatedRevolvingCreditAndSecurityAgreementMember_lbl" xml:lang="en-US"> Amended And Restated Revolving Credit And Security Agreement </label>
<loc xlink:type="locator" xlink:href="hdsn-20201231.xsd#hdsn_SwingLineLoanMember" xlink:label="hdsn_SwingLineLoanMember"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="hdsn_SwingLineLoanMember" xlink:to="hdsn_SwingLineLoanMember_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="hdsn_SwingLineLoanMember_lbl" xml:lang="en-US"> Swing Line Loan [Member] </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="hdsn_SwingLineLoanMember_lbl" xml:lang="en-US"> Swing Line Loan [Member] </label>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_LetterOfCreditMember" xlink:label="us-gaap_LetterOfCreditMember"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_LetterOfCreditMember" xlink:to="us-gaap_LetterOfCreditMember_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_LetterOfCreditMember_lbl" xml:lang="en-US"> Letter Of Credit [Member] </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_LetterOfCreditMember_lbl" xml:lang="en-US"> Letter of Credit [Member] </label>
<loc xlink:type="locator" xlink:href="hdsn-20201231.xsd#hdsn_TermLoanFacilityMember" xlink:label="hdsn_TermLoanFacilityMember"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="hdsn_TermLoanFacilityMember" xlink:to="hdsn_TermLoanFacilityMember_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:label="hdsn_TermLoanFacilityMember_lbl" xml:lang="en-US"> Pertains to the term loan facility. </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="hdsn_TermLoanFacilityMember_lbl" xml:lang="en-US"> Term Loan Facility [Member] </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="hdsn_TermLoanFacilityMember_lbl" xml:lang="en-US"> Term Loan Facility [Member] </label>
<loc xlink:type="locator" xlink:href="hdsn-20201231.xsd#hdsn_WaiverAndFirstAmendmentToTermLoanCreditAndSecurityAgreementMember" xlink:label="hdsn_WaiverAndFirstAmendmentToTermLoanCreditAndSecurityAgreementMember"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="hdsn_WaiverAndFirstAmendmentToTermLoanCreditAndSecurityAgreementMember" xlink:to="hdsn_WaiverAndFirstAmendmentToTermLoanCreditAndSecurityAgreementMember_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:label="hdsn_WaiverAndFirstAmendmentToTermLoanCreditAndSecurityAgreementMember_lbl" xml:lang="en-US"> Information pertaining to the Waiver and First Amendment to Term Loan Credit and Security Agreement. </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="hdsn_WaiverAndFirstAmendmentToTermLoanCreditAndSecurityAgreementMember_lbl" xml:lang="en-US"> Waiver And First Amendment To Term Loan Credit And Security Agreement [Member] </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="hdsn_WaiverAndFirstAmendmentToTermLoanCreditAndSecurityAgreementMember_lbl" xml:lang="en-US"> First Amendment </label>
<loc xlink:type="locator" xlink:href="hdsn-20201231.xsd#hdsn_FourthAmendmentMember" xlink:label="hdsn_FourthAmendmentMember"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="hdsn_FourthAmendmentMember" xlink:to="hdsn_FourthAmendmentMember_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:label="hdsn_FourthAmendmentMember_lbl" xml:lang="en-US"> Represents information pertaining to fourth amendment. </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="hdsn_FourthAmendmentMember_lbl" xml:lang="en-US"> Fourth Amendment [Member] </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="hdsn_FourthAmendmentMember_lbl" xml:lang="en-US"> Fourth Amendment </label>
<loc xlink:type="locator" xlink:href="hdsn-20201231.xsd#hdsn_FifthAmendmentToTermLoanCreditAndSecurityAgreementMember" xlink:label="hdsn_FifthAmendmentToTermLoanCreditAndSecurityAgreementMember"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="hdsn_FifthAmendmentToTermLoanCreditAndSecurityAgreementMember" xlink:to="hdsn_FifthAmendmentToTermLoanCreditAndSecurityAgreementMember_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:label="hdsn_FifthAmendmentToTermLoanCreditAndSecurityAgreementMember_lbl" xml:lang="en-US"> Represents information pertaining to fifth amendment to Term Loan Credit and Security Agreement. </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="hdsn_FifthAmendmentToTermLoanCreditAndSecurityAgreementMember_lbl" xml:lang="en-US"> Fifth Amendment To Term Loan Credit And Security Agreement [Member] </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="hdsn_FifthAmendmentToTermLoanCreditAndSecurityAgreementMember_lbl" xml:lang="en-US"> Fifth Amendment To Term Loan Credit And Security Agreement [Member] </label>
<loc xlink:type="locator" xlink:href="hdsn-20201231.xsd#hdsn_VehicleAndEquipmentLoansMember" xlink:label="hdsn_VehicleAndEquipmentLoansMember"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="hdsn_VehicleAndEquipmentLoansMember" xlink:to="hdsn_VehicleAndEquipmentLoansMember_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="hdsn_VehicleAndEquipmentLoansMember_lbl" xml:lang="en-US"> Vehicle And Equipment Loans [Member] </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="hdsn_VehicleAndEquipmentLoansMember_lbl" xml:lang="en-US"> Vehicle and Equipment Loans </label>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_RevolvingCreditFacilityMember" xlink:label="us-gaap_RevolvingCreditFacilityMember"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_RevolvingCreditFacilityMember" xlink:to="us-gaap_RevolvingCreditFacilityMember_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_RevolvingCreditFacilityMember_lbl" xml:lang="en-US"> Revolving Credit Facility [Member] </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_RevolvingCreditFacilityMember_lbl" xml:lang="en-US"> Revolving Credit Facility </label>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_VariableRateAxis" xlink:label="us-gaap_VariableRateAxis"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_VariableRateAxis" xlink:to="us-gaap_VariableRateAxis_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_VariableRateAxis_lbl" xml:lang="en-US"> Variable Rate [Axis] </label>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_VariableRateDomain" xlink:label="us-gaap_VariableRateDomain"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_VariableRateDomain" xlink:to="us-gaap_VariableRateDomain_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_VariableRateDomain_lbl" xml:lang="en-US"> Variable Rate [Domain] </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_VariableRateDomain_lbl" xml:lang="en-US"> Variable Rate [Domain] </label>
<loc xlink:type="locator" xlink:href="hdsn-20201231.xsd#hdsn_LondonInterbankOfferedRateDailyLiborMember" xlink:label="hdsn_LondonInterbankOfferedRateDailyLiborMember"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="hdsn_LondonInterbankOfferedRateDailyLiborMember" xlink:to="hdsn_LondonInterbankOfferedRateDailyLiborMember_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:label="hdsn_LondonInterbankOfferedRateDailyLiborMember_lbl" xml:lang="en-US"> Daily interest rate at which a bank borrows funds from other banks in the London interbank market. </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="hdsn_LondonInterbankOfferedRateDailyLiborMember_lbl" xml:lang="en-US"> London Interbank Offered Rate Daily Libor [Member] </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="hdsn_LondonInterbankOfferedRateDailyLiborMember_lbl" xml:lang="en-US"> London Interbank Offered Rate Daily Libor [Member] </label>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_FederalFundsPurchasedMember" xlink:label="us-gaap_FederalFundsPurchasedMember"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_FederalFundsPurchasedMember" xlink:to="us-gaap_FederalFundsPurchasedMember_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_FederalFundsPurchasedMember_lbl" xml:lang="en-US"> Federal Funds Purchased [Member] </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_FederalFundsPurchasedMember_lbl" xml:lang="en-US"> Federal Funds Purchased [Member] </label>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_EurodollarMember" xlink:label="us-gaap_EurodollarMember"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_EurodollarMember" xlink:to="us-gaap_EurodollarMember_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_EurodollarMember_lbl" xml:lang="en-US"> Eurodollar [Member] </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_EurodollarMember_lbl" xml:lang="en-US"> Euro Dollar </label>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ShortTermDebtTypeAxis" xlink:label="us-gaap_ShortTermDebtTypeAxis"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_ShortTermDebtTypeAxis" xlink:to="us-gaap_ShortTermDebtTypeAxis_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_ShortTermDebtTypeAxis_lbl" xml:lang="en-US"> Short-term Debt, Type [Axis] </label>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ShortTermDebtTypeDomain" xlink:label="us-gaap_ShortTermDebtTypeDomain"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_ShortTermDebtTypeDomain" xlink:to="us-gaap_ShortTermDebtTypeDomain_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_ShortTermDebtTypeDomain_lbl" xml:lang="en-US"> Short Term Debt Type [Domain] </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_ShortTermDebtTypeDomain_lbl" xml:lang="en-US"> Short-term Debt, Type [Domain] </label>
<loc xlink:type="locator" xlink:href="hdsn-20201231.xsd#hdsn_FCCRMember" xlink:label="hdsn_FCCRMember"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="hdsn_FCCRMember" xlink:to="hdsn_FCCRMember_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:label="hdsn_FCCRMember_lbl" xml:lang="en-US"> Fixed Charge Coverage Ratio </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="hdsn_FCCRMember_lbl" xml:lang="en-US"> F C C R [Member] </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="hdsn_FCCRMember_lbl" xml:lang="en-US"> FCCR [Member] </label>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_LongtermDebtTypeAxis" xlink:label="us-gaap_LongtermDebtTypeAxis"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_LongtermDebtTypeAxis" xlink:to="us-gaap_LongtermDebtTypeAxis_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_LongtermDebtTypeAxis_lbl" xml:lang="en-US"> Long-term Debt, Type [Axis] </label>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_LongtermDebtTypeDomain" xlink:label="us-gaap_LongtermDebtTypeDomain"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_LongtermDebtTypeDomain" xlink:to="us-gaap_LongtermDebtTypeDomain_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_LongtermDebtTypeDomain_lbl" xml:lang="en-US"> Longterm Debt Type [Domain] </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_LongtermDebtTypeDomain_lbl" xml:lang="en-US"> Long-term Debt, Type [Domain] </label>
<loc xlink:type="locator" xlink:href="hdsn-20201231.xsd#hdsn_PaycheckProtectionProgramMember" xlink:label="hdsn_PaycheckProtectionProgramMember"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="hdsn_PaycheckProtectionProgramMember" xlink:to="hdsn_PaycheckProtectionProgramMember_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:label="hdsn_PaycheckProtectionProgramMember_lbl" xml:lang="en-US"> This represents Paycheck Protection Program. </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="hdsn_PaycheckProtectionProgramMember_lbl" xml:lang="en-US"> Paycheck Protection Program [Member] </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="hdsn_PaycheckProtectionProgramMember_lbl" xml:lang="en-US"> Paycheck Protection Program [Member] </label>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DebtInstrumentAxis" xlink:label="us-gaap_DebtInstrumentAxis"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_DebtInstrumentAxis" xlink:to="us-gaap_DebtInstrumentAxis_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_DebtInstrumentAxis_lbl" xml:lang="en-US"> Debt Instrument [Axis] </label>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DebtInstrumentNameDomain" xlink:label="us-gaap_DebtInstrumentNameDomain"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_DebtInstrumentNameDomain" xlink:to="us-gaap_DebtInstrumentNameDomain_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_DebtInstrumentNameDomain_lbl" xml:lang="en-US"> Debt Instrument Name [Domain] </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_DebtInstrumentNameDomain_lbl" xml:lang="en-US"> Debt Instrument, Name [Domain] </label>
<loc xlink:type="locator" xlink:href="hdsn-20201231.xsd#hdsn_CaresActLoanMember" xlink:label="hdsn_CaresActLoanMember"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="hdsn_CaresActLoanMember" xlink:to="hdsn_CaresActLoanMember_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:label="hdsn_CaresActLoanMember_lbl" xml:lang="en-US"> Represents the information pertaining to CARES Act Loan. </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="hdsn_CaresActLoanMember_lbl" xml:lang="en-US"> Cares Act Loan [Member] </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="hdsn_CaresActLoanMember_lbl" xml:lang="en-US"> CARES Act Loan [Member] </label>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/srt/2020/elts/srt-2020-01-31.xsd#srt_StatementScenarioAxis" xlink:label="srt_StatementScenarioAxis"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="srt_StatementScenarioAxis" xlink:to="srt_StatementScenarioAxis_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="srt_StatementScenarioAxis_lbl" xml:lang="en-US"> Scenario [Axis] </label>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/srt/2020/elts/srt-2020-01-31.xsd#srt_ScenarioUnspecifiedDomain" xlink:label="srt_ScenarioUnspecifiedDomain"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="srt_ScenarioUnspecifiedDomain" xlink:to="srt_ScenarioUnspecifiedDomain_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="srt_ScenarioUnspecifiedDomain_lbl" xml:lang="en-US"> Scenario Unspecified [Domain] </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="srt_ScenarioUnspecifiedDomain_lbl" xml:lang="en-US"> Scenario, Unspecified [Domain] </label>
<loc xlink:type="locator" xlink:href="hdsn-20201231.xsd#hdsn_EffectiveMarch312020Member" xlink:label="hdsn_EffectiveMarch312020Member"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="hdsn_EffectiveMarch312020Member" xlink:to="hdsn_EffectiveMarch312020Member_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:label="hdsn_EffectiveMarch312020Member_lbl" xml:lang="en-US"> Represents the information pertaining to repayment of principal effective March 31, 2020. </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="hdsn_EffectiveMarch312020Member_lbl" xml:lang="en-US"> Effective March312020 [Member] </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="hdsn_EffectiveMarch312020Member_lbl" xml:lang="en-US"> Effective March 31, 2020 [Member] </label>
<loc xlink:type="locator" xlink:href="hdsn-20201231.xsd#hdsn_EffectiveDecember312020Member" xlink:label="hdsn_EffectiveDecember312020Member"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="hdsn_EffectiveDecember312020Member" xlink:to="hdsn_EffectiveDecember312020Member_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:label="hdsn_EffectiveDecember312020Member_lbl" xml:lang="en-US"> Represents the information pertaining to repayment of principal effective December 31, 2020 </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="hdsn_EffectiveDecember312020Member_lbl" xml:lang="en-US"> Effective December312020 [Member] </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="hdsn_EffectiveDecember312020Member_lbl" xml:lang="en-US"> Effective December 31, 2020 [Member] </label>
<loc xlink:type="locator" xlink:href="hdsn-20201231.xsd#hdsn_ThroughMarch312020Member" xlink:label="hdsn_ThroughMarch312020Member"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="hdsn_ThroughMarch312020Member" xlink:to="hdsn_ThroughMarch312020Member_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:label="hdsn_ThroughMarch312020Member_lbl" xml:lang="en-US"> Represents the information pertaining to repayment of principal through March 31, 2020. </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="hdsn_ThroughMarch312020Member_lbl" xml:lang="en-US"> Through March312020 [Member] </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="hdsn_ThroughMarch312020Member_lbl" xml:lang="en-US"> Through March 31, 2020 [Member] </label>
<loc xlink:type="locator" xlink:href="hdsn-20201231.xsd#hdsn_FromApril12020ThroughMarch312021Member" xlink:label="hdsn_FromApril12020ThroughMarch312021Member"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="hdsn_FromApril12020ThroughMarch312021Member" xlink:to="hdsn_FromApril12020ThroughMarch312021Member_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:label="hdsn_FromApril12020ThroughMarch312021Member_lbl" xml:lang="en-US"> Represents the information pertaining to repayment of principal from April 1, 2020 through March 31, 2021. </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="hdsn_FromApril12020ThroughMarch312021Member_lbl" xml:lang="en-US"> From April12020 Through March312021 [Member] </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="hdsn_FromApril12020ThroughMarch312021Member_lbl" xml:lang="en-US"> From April 1, 2020 through March 31, 2021 [Member] </label>
<loc xlink:type="locator" xlink:href="hdsn-20201231.xsd#hdsn_FromApril12021AndThereafterMember" xlink:label="hdsn_FromApril12021AndThereafterMember"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="hdsn_FromApril12021AndThereafterMember" xlink:to="hdsn_FromApril12021AndThereafterMember_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:label="hdsn_FromApril12021AndThereafterMember_lbl" xml:lang="en-US"> Represents the information pertaining to repayment of principal from April 1, 2021 and thereafter. </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="hdsn_FromApril12021AndThereafterMember_lbl" xml:lang="en-US"> From April12021 And Thereafter [Member] </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="hdsn_FromApril12021AndThereafterMember_lbl" xml:lang="en-US"> From April 1, 2021 and thereafter [Member] </label>
<loc xlink:type="locator" xlink:href="hdsn-20201231.xsd#hdsn_PropertyLocationAxis" xlink:label="hdsn_PropertyLocationAxis"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="hdsn_PropertyLocationAxis" xlink:to="hdsn_PropertyLocationAxis_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="hdsn_PropertyLocationAxis_lbl" xml:lang="en-US"> Property Location [Axis] </label>
<loc xlink:type="locator" xlink:href="hdsn-20201231.xsd#hdsn_PropertyLocationDomain" xlink:label="hdsn_PropertyLocationDomain"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="hdsn_PropertyLocationDomain" xlink:to="hdsn_PropertyLocationDomain_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="hdsn_PropertyLocationDomain_lbl" xml:lang="en-US"> Property Location [Domain] </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="hdsn_PropertyLocationDomain_lbl" xml:lang="en-US"> Property Location [Domain] </label>
<loc xlink:type="locator" xlink:href="hdsn-20201231.xsd#hdsn_AuburnWashingtonMember" xlink:label="hdsn_AuburnWashingtonMember"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="hdsn_AuburnWashingtonMember" xlink:to="hdsn_AuburnWashingtonMember_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="hdsn_AuburnWashingtonMember_lbl" xml:lang="en-US"> Auburn Washington [Member] </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="hdsn_AuburnWashingtonMember_lbl" xml:lang="en-US"> Auburn Washington [Member] </label>
<loc xlink:type="locator" xlink:href="hdsn-20201231.xsd#hdsn_BatonRougeLouisianaMember" xlink:label="hdsn_BatonRougeLouisianaMember"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="hdsn_BatonRougeLouisianaMember" xlink:to="hdsn_BatonRougeLouisianaMember_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="hdsn_BatonRougeLouisianaMember_lbl" xml:lang="en-US"> Baton Rouge Louisiana [Member] </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="hdsn_BatonRougeLouisianaMember_lbl" xml:lang="en-US"> Baton Rouge Louisiana [Member] </label>
<loc xlink:type="locator" xlink:href="hdsn-20201231.xsd#hdsn_ChampaignIllinoisMember" xlink:label="hdsn_ChampaignIllinoisMember"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="hdsn_ChampaignIllinoisMember" xlink:to="hdsn_ChampaignIllinoisMember_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="hdsn_ChampaignIllinoisMember_lbl" xml:lang="en-US"> Champaign Illinois [Member] </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="hdsn_ChampaignIllinoisMember_lbl" xml:lang="en-US"> Champaign Illinois [Member] </label>
<loc xlink:type="locator" xlink:href="hdsn-20201231.xsd#hdsn_ChampaignIllinois2ndLocationMember" xlink:label="hdsn_ChampaignIllinois2ndLocationMember"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="hdsn_ChampaignIllinois2ndLocationMember" xlink:to="hdsn_ChampaignIllinois2ndLocationMember_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:label="hdsn_ChampaignIllinois2ndLocationMember_lbl" xml:lang="en-US"> n/a </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="hdsn_ChampaignIllinois2ndLocationMember_lbl" xml:lang="en-US"> Champaign Illinois2nd Location [Member] </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="hdsn_ChampaignIllinois2ndLocationMember_lbl" xml:lang="en-US"> Champaign, Illinois (2nd location) [Member] </label>
<loc xlink:type="locator" xlink:href="hdsn-20201231.xsd#hdsn_CharlotteNorthCarolinaMember" xlink:label="hdsn_CharlotteNorthCarolinaMember"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="hdsn_CharlotteNorthCarolinaMember" xlink:to="hdsn_CharlotteNorthCarolinaMember_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="hdsn_CharlotteNorthCarolinaMember_lbl" xml:lang="en-US"> Charlotte North Carolina [Member] </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="hdsn_CharlotteNorthCarolinaMember_lbl" xml:lang="en-US"> CharlotteNorthCarolina [Member] </label>
<loc xlink:type="locator" xlink:href="hdsn-20201231.xsd#hdsn_EscondidoCaliforniaMember" xlink:label="hdsn_EscondidoCaliforniaMember"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="hdsn_EscondidoCaliforniaMember" xlink:to="hdsn_EscondidoCaliforniaMember_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="hdsn_EscondidoCaliforniaMember_lbl" xml:lang="en-US"> Escondido California [Member] </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="hdsn_EscondidoCaliforniaMember_lbl" xml:lang="en-US"> EscondidoCalifornia [Member] </label>
<loc xlink:type="locator" xlink:href="hdsn-20201231.xsd#hdsn_HampsteadNewHampshireMemberMember" xlink:label="hdsn_HampsteadNewHampshireMemberMember"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="hdsn_HampsteadNewHampshireMemberMember" xlink:to="hdsn_HampsteadNewHampshireMemberMember_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="hdsn_HampsteadNewHampshireMemberMember_lbl" xml:lang="en-US"> Hampstead New Hampshire Member [Member] </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="hdsn_HampsteadNewHampshireMemberMember_lbl" xml:lang="en-US"> HampsteadNewHampshireMember [Member] </label>
<loc xlink:type="locator" xlink:href="hdsn-20201231.xsd#hdsn_LongBeachCaliforniaMember" xlink:label="hdsn_LongBeachCaliforniaMember"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="hdsn_LongBeachCaliforniaMember" xlink:to="hdsn_LongBeachCaliforniaMember_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:label="hdsn_LongBeachCaliforniaMember_lbl" xml:lang="en-US"> n/a </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="hdsn_LongBeachCaliforniaMember_lbl" xml:lang="en-US"> Long Beach California [Member] </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="hdsn_LongBeachCaliforniaMember_lbl" xml:lang="en-US"> Long Beach California [Member] </label>
<loc xlink:type="locator" xlink:href="hdsn-20201231.xsd#hdsn_LongIslandCityNewYorkMember" xlink:label="hdsn_LongIslandCityNewYorkMember"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="hdsn_LongIslandCityNewYorkMember" xlink:to="hdsn_LongIslandCityNewYorkMember_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:label="hdsn_LongIslandCityNewYorkMember_lbl" xml:lang="en-US"> n/a </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="hdsn_LongIslandCityNewYorkMember_lbl" xml:lang="en-US"> Long Island City New York [Member] </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="hdsn_LongIslandCityNewYorkMember_lbl" xml:lang="en-US"> Long Island City New York [Member] </label>
<loc xlink:type="locator" xlink:href="hdsn-20201231.xsd#hdsn_OntarioCaliforniaMemberMember" xlink:label="hdsn_OntarioCaliforniaMemberMember"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="hdsn_OntarioCaliforniaMemberMember" xlink:to="hdsn_OntarioCaliforniaMemberMember_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="hdsn_OntarioCaliforniaMemberMember_lbl" xml:lang="en-US"> Ontario California Member [Member] </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="hdsn_OntarioCaliforniaMemberMember_lbl" xml:lang="en-US"> OntarioCaliforniaMember [Member] </label>
<loc xlink:type="locator" xlink:href="hdsn-20201231.xsd#hdsn_PearlRiverNewYorkMember" xlink:label="hdsn_PearlRiverNewYorkMember"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="hdsn_PearlRiverNewYorkMember" xlink:to="hdsn_PearlRiverNewYorkMember_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="hdsn_PearlRiverNewYorkMember_lbl" xml:lang="en-US"> Pearl River New York [Member] </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="hdsn_PearlRiverNewYorkMember_lbl" xml:lang="en-US"> Pearl River New York [Member] </label>
<loc xlink:type="locator" xlink:href="hdsn-20201231.xsd#hdsn_RiversideCaliforniaMemberMember" xlink:label="hdsn_RiversideCaliforniaMemberMember"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="hdsn_RiversideCaliforniaMemberMember" xlink:to="hdsn_RiversideCaliforniaMemberMember_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="hdsn_RiversideCaliforniaMemberMember_lbl" xml:lang="en-US"> Riverside California Member [Member] </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="hdsn_RiversideCaliforniaMemberMember_lbl" xml:lang="en-US"> RiversideCaliforniaMember [Member] </label>
<loc xlink:type="locator" xlink:href="hdsn-20201231.xsd#hdsn_RantoulIllinoisMember" xlink:label="hdsn_RantoulIllinoisMember"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="hdsn_RantoulIllinoisMember" xlink:to="hdsn_RantoulIllinoisMember_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:label="hdsn_RantoulIllinoisMember_lbl" xml:lang="en-US"> n/a </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="hdsn_RantoulIllinoisMember_lbl" xml:lang="en-US"> Rantoul Illinois [Member] </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="hdsn_RantoulIllinoisMember_lbl" xml:lang="en-US"> Rantoul, Illinois [Member] </label>
<loc xlink:type="locator" xlink:href="hdsn-20201231.xsd#hdsn_SmyrnaGeorgiaMemberMember" xlink:label="hdsn_SmyrnaGeorgiaMemberMember"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="hdsn_SmyrnaGeorgiaMemberMember" xlink:to="hdsn_SmyrnaGeorgiaMemberMember_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="hdsn_SmyrnaGeorgiaMemberMember_lbl" xml:lang="en-US"> Smyrna Georgia Member [Member] </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="hdsn_SmyrnaGeorgiaMemberMember_lbl" xml:lang="en-US"> SmyrnaGeorgiaMember [Member] </label>
<loc xlink:type="locator" xlink:href="hdsn-20201231.xsd#hdsn_StonyPointNyMemberMember" xlink:label="hdsn_StonyPointNyMemberMember"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="hdsn_StonyPointNyMemberMember" xlink:to="hdsn_StonyPointNyMemberMember_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="hdsn_StonyPointNyMemberMember_lbl" xml:lang="en-US"> Stony Point Ny Member [Member] </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="hdsn_StonyPointNyMemberMember_lbl" xml:lang="en-US"> StonyPointNyMember [Member] </label>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_OptionIndexedToIssuersEquityTypeAxis" xlink:label="us-gaap_OptionIndexedToIssuersEquityTypeAxis"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_OptionIndexedToIssuersEquityTypeAxis" xlink:to="us-gaap_OptionIndexedToIssuersEquityTypeAxis_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_OptionIndexedToIssuersEquityTypeAxis_lbl" xml:lang="en-US"> Option Indexed to Issuer's Equity, Type [Axis] </label>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_OptionIndexedToIssuersEquityTypeDomain" xlink:label="us-gaap_OptionIndexedToIssuersEquityTypeDomain"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_OptionIndexedToIssuersEquityTypeDomain" xlink:to="us-gaap_OptionIndexedToIssuersEquityTypeDomain_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_OptionIndexedToIssuersEquityTypeDomain_lbl" xml:lang="en-US"> Option Indexed To Issuers Equity Type [Domain] </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_OptionIndexedToIssuersEquityTypeDomain_lbl" xml:lang="en-US"> Option Indexed to Issuer's Equity, Type [Domain] </label>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_EmployeeStockOptionMember" xlink:label="us-gaap_EmployeeStockOptionMember"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_EmployeeStockOptionMember" xlink:to="us-gaap_EmployeeStockOptionMember_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_EmployeeStockOptionMember_lbl" xml:lang="en-US"> Employee Stock Option [Member] </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_EmployeeStockOptionMember_lbl" xml:lang="en-US"> Employee Stock Option [Member] </label>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DeferredCompensationArrangementWithIndividualShareBasedPaymentsByTypeOfDeferredCompensationAxis" xlink:label="us-gaap_DeferredCompensationArrangementWithIndividualShareBasedPaymentsByTypeOfDeferredCompensationAxis"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_DeferredCompensationArrangementWithIndividualShareBasedPaymentsByTypeOfDeferredCompensationAxis" xlink:to="us-gaap_DeferredCompensationArrangementWithIndividualShareBasedPaymentsByTypeOfDeferredCompensationAxis_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_DeferredCompensationArrangementWithIndividualShareBasedPaymentsByTypeOfDeferredCompensationAxis_lbl" xml:lang="en-US"> Equity-Based Arrangements, Individual Contracts, Type of Deferred Compensation [Axis] </label>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_EquityBasedArrangementsIndividualContractsTypeOfDeferredCompensationDomain" xlink:label="us-gaap_EquityBasedArrangementsIndividualContractsTypeOfDeferredCompensationDomain"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_EquityBasedArrangementsIndividualContractsTypeOfDeferredCompensationDomain" xlink:to="us-gaap_EquityBasedArrangementsIndividualContractsTypeOfDeferredCompensationDomain_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_EquityBasedArrangementsIndividualContractsTypeOfDeferredCompensationDomain_lbl" xml:lang="en-US"> Equity Based Arrangements Individual Contracts Type Of Deferred Compensation [Domain] </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_EquityBasedArrangementsIndividualContractsTypeOfDeferredCompensationDomain_lbl" xml:lang="en-US"> Equity-Based Arrangements, Individual Contracts, Type of Deferred Compensation [Domain] </label>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_PlanNameAxis" xlink:label="us-gaap_PlanNameAxis"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_PlanNameAxis" xlink:to="us-gaap_PlanNameAxis_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_PlanNameAxis_lbl" xml:lang="en-US"> Plan Name [Axis] </label>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_PlanNameDomain" xlink:label="us-gaap_PlanNameDomain"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_PlanNameDomain" xlink:to="us-gaap_PlanNameDomain_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_PlanNameDomain_lbl" xml:lang="en-US"> Plan Name [Domain] </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_PlanNameDomain_lbl" xml:lang="en-US"> Plan Name [Domain] </label>
<loc xlink:type="locator" xlink:href="hdsn-20201231.xsd#hdsn_TwoThousandAndFourteenStockIncentivePlanMember" xlink:label="hdsn_TwoThousandAndFourteenStockIncentivePlanMember"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="hdsn_TwoThousandAndFourteenStockIncentivePlanMember" xlink:to="hdsn_TwoThousandAndFourteenStockIncentivePlanMember_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="hdsn_TwoThousandAndFourteenStockIncentivePlanMember_lbl" xml:lang="en-US"> Two Thousand And Fourteen Stock Incentive Plan [Member] </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="hdsn_TwoThousandAndFourteenStockIncentivePlanMember_lbl" xml:lang="en-US"> 2014 Stock Incentive Plan </label>
<loc xlink:type="locator" xlink:href="hdsn-20201231.xsd#hdsn_TwoThousandAndEighteenStockIncentivePlanMember" xlink:label="hdsn_TwoThousandAndEighteenStockIncentivePlanMember"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="hdsn_TwoThousandAndEighteenStockIncentivePlanMember" xlink:to="hdsn_TwoThousandAndEighteenStockIncentivePlanMember_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:label="hdsn_TwoThousandAndEighteenStockIncentivePlanMember_lbl" xml:lang="en-US"> Two Thousand And Eighteen Stock Incentive Plan </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="hdsn_TwoThousandAndEighteenStockIncentivePlanMember_lbl" xml:lang="en-US"> Two Thousand And Eighteen Stock Incentive Plan [Member] </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="hdsn_TwoThousandAndEighteenStockIncentivePlanMember_lbl" xml:lang="en-US"> 2018 Stock Incentive Plan </label>
<loc xlink:type="locator" xlink:href="hdsn-20201231.xsd#hdsn_TwoThousandAndTwentyStockIncentivePlanMember" xlink:label="hdsn_TwoThousandAndTwentyStockIncentivePlanMember"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="hdsn_TwoThousandAndTwentyStockIncentivePlanMember" xlink:to="hdsn_TwoThousandAndTwentyStockIncentivePlanMember_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:label="hdsn_TwoThousandAndTwentyStockIncentivePlanMember_lbl" xml:lang="en-US"> Represents the information pertaining to two thousand and twenty stock incentive plan. </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="hdsn_TwoThousandAndTwentyStockIncentivePlanMember_lbl" xml:lang="en-US"> Two Thousand And Twenty Stock Incentive Plan [Member] </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="hdsn_TwoThousandAndTwentyStockIncentivePlanMember_lbl" xml:lang="en-US"> 2020 Stock Incentive Plan </label>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/srt/2020/elts/srt-2020-01-31.xsd#srt_TitleOfIndividualAxis" xlink:label="srt_TitleOfIndividualAxis"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="srt_TitleOfIndividualAxis" xlink:to="srt_TitleOfIndividualAxis_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="srt_TitleOfIndividualAxis_lbl" xml:lang="en-US"> Title of Individual [Axis] </label>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/srt/2020/elts/srt-2020-01-31.xsd#srt_TitleOfIndividualWithRelationshipToEntityDomain" xlink:label="srt_TitleOfIndividualWithRelationshipToEntityDomain"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="srt_TitleOfIndividualWithRelationshipToEntityDomain" xlink:to="srt_TitleOfIndividualWithRelationshipToEntityDomain_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="srt_TitleOfIndividualWithRelationshipToEntityDomain_lbl" xml:lang="en-US"> Title Of Individual With Relationship To Entity [Domain] </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="srt_TitleOfIndividualWithRelationshipToEntityDomain_lbl" xml:lang="en-US"> Title of Individual [Domain] </label>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/srt/2020/elts/srt-2020-01-31.xsd#srt_VicePresidentMember" xlink:label="srt_VicePresidentMember"/>
<labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="srt_VicePresidentMember" xlink:to="srt_VicePresidentMember_lbl"/>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="srt_VicePresidentMember_lbl" xml:lang="en-US"> Vice President [Member] </label>
<label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="srt_VicePresidentMember_lbl" xml:lang="en-US"> Stephen P. Mandracchia </label>
</labelLink>
</linkbase>

3 Subsequent Filings that Reference this Filing

  As Of               Filer                 Filing    For·On·As Docs:Size             Issuer                      Filing Agent

 3/14/24  Hudson Technologies Inc./NY       10-K       12/31/23   80:7.9M                                   Toppan Merrill/FA2
 3/14/23  Hudson Technologies Inc./NY       10-K       12/31/22   77:7.2M                                   Toppan Merrill/FA2
 3/24/22  Hudson Technologies Inc./NY       10-K       12/31/21   83:7.8M                                   Toppan Merrill/FA2

32 Previous Filings that this Filing References

  As Of               Filer                 Filing    For·On·As Docs:Size             Issuer                      Filing Agent

 9/16/20  Hudson Technologies Inc./NY       8-K:5,9     9/14/20    5:232K                                   Toppan Merrill/FA
 7/20/20  Hudson Technologies Inc./NY       8-K:5,9     7/15/20    3:160K                                   Toppan Merrill/FA
 6/30/20  Hudson Technologies Inc./NY       S-8         6/30/20    4:137K                                   Toppan Merrill/FA
 5/15/20  Hudson Technologies Inc./NY       10-Q        3/31/20   56:4.2M                                   Toppan Merrill/FA
 3/13/20  Hudson Technologies Inc./NY       10-K       12/31/19   78:6.5M                                   Toppan Merrill/FA
12/20/19  Hudson Technologies Inc./NY       8-K:1,2,5,812/19/19    8:1.9M                                   Toppan Merrill/FA
 9/23/19  Hudson Technologies Inc./NY       8-K:5,9     9/20/19    4:317K                                   Toppan Merrill/FA
 5/02/19  Hudson Technologies Inc./NY       10-Q        3/31/19   57:6M                                     Toppan Merrill/FA
 3/15/19  Hudson Technologies Inc./NY       10-K       12/31/18   86:11M                                    Toppan Merrill/FA
12/21/18  Hudson Technologies Inc./NY       S-8        12/21/18    5:141K                                   Toppan Merrill/FA
12/03/18  Hudson Technologies Inc./NY       8-K:2,9    11/30/18    4:198K                                   Toppan Merrill/FA
11/23/18  Hudson Technologies Inc./NY       8-K:2,9    11/21/18    3:98K                                    Toppan Merrill/FA
11/15/18  Hudson Technologies Inc./NY       8-K:2,9    11/14/18    3:64K                                    Toppan Merrill/FA
10/16/18  Hudson Technologies Inc./NY       8-K:2,8,9  10/15/18    3:75K                                    Toppan Merrill/FA
 8/15/18  Hudson Technologies Inc./NY       8-K:2,8,9   8/14/18    3:120K                                   Toppan Merrill/FA
10/11/17  Hudson Technologies Inc./NY       8-K:2,9    10/10/17    6:1.6M                                   Toppan Merrill/FA
 8/09/17  Hudson Technologies Inc./NY       8-K:1,8,9   8/09/17    3:511K                                   Toppan Merrill/FA
 9/09/16  Hudson Technologies Inc./NY       8-K:5,9     9/05/16    2:101K                                   Toppan Merrill/FA
 3/11/16  Hudson Technologies Inc./NY       10-K       12/31/15   71:5.2M                                   Toppan Merrill/FA
11/10/15  Hudson Technologies Inc./NY       10-Q        9/30/15   37:2.4M                                   Toppan Merrill/FA
10/29/14  Hudson Technologies Inc./NY       10-Q        9/30/14   48:3.3M                                   Toppan Merrill/FA
 8/12/14  Hudson Technologies Inc./NY       DEF 14A     9/17/14    1:387K                                   Toppan Merrill/FA
 2/28/14  Hudson Technologies Inc./NY       10-K       12/31/13   73:6.9M                                   Toppan Merrill/FA
10/31/12  Hudson Technologies Inc./NY       10-Q        9/30/12   37:2.2M                                   Toppan Merrill/FA
 3/05/09  Hudson Technologies Inc./NY       10-K       12/31/08   16:764K                                   Mandracchia Stephen P
 7/29/08  Hudson Technologies Inc./NY       DEF 14A     8/27/08    1:571K                                   Toppan Merrill/FA
 5/31/05  Hudson Technologies Inc./NY       8-K:8       5/31/05    2:53K                                    Mandracchia Stephen P
 8/18/04  Hudson Technologies Inc./NY       DEF 14A    12/31/03    1:182K                                   Mandracchia Stephen P
 4/15/03  Hudson Technologies Inc./NY       10KSB      12/31/02    8:259K                                   Edgar Ease Svc Bureau/FA
 3/29/02  Hudson Technologies Inc./NY       10KSB      12/31/01    6:164K                                   Document Techs Inc./FA
 3/29/01  Hudson Technologies Inc./NY       10-K       12/31/00    7:508K                                   Document Techs Inc./FA
 8/13/99  Hudson Technologies Inc./NY       10QSB       6/30/99    5:153K                                   Document Techs Inc./FA
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