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| <xsd:element id="hdsn_ScheduleOfOperatingLeaseInBalanceSheetClassificationTableTextBlock" name="ScheduleOfOperatingLeaseInBalanceSheetClassificationTableTextBlock" nillable="true" type="dtr-types:textBlockItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration"/> |
| <xsd:element id="hdsn_ScheduleOfOperatingLeaseOtherInformationTableTextBlock" name="ScheduleOfOperatingLeaseOtherInformationTableTextBlock" nillable="true" type="dtr-types:textBlockItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration"/> |
| <xsd:element name="SignificantAccountingPoliciesTable" type="xbrli:stringItemType" abstract="true" xbrli:periodType="duration" nillable="true" id="hdsn_SignificantAccountingPoliciesTable" substitutionGroup="xbrldt:hypercubeItem"/> |
| <xsd:element name="SignificantAccountingPoliciesLineItems" type="xbrli:stringItemType" abstract="true" xbrli:periodType="duration" nillable="true" id="hdsn_SignificantAccountingPoliciesLineItems" substitutionGroup="xbrli:item"/> |
| <xsd:element name="ExpirationPeriodAxis" type="xbrli:stringItemType" abstract="true" xbrli:periodType="duration" nillable="true" id="hdsn_ExpirationPeriodAxis" substitutionGroup="xbrldt:dimensionItem"/> |
| <xsd:element name="ExpirationPeriodDomain" type="dtr-types:domainItemType" abstract="true" xbrli:periodType="duration" nillable="true" id="hdsn_ExpirationPeriodDomain" substitutionGroup="xbrli:item"/> |
| <xsd:element name="CylindersMember" type="dtr-types:domainItemType" abstract="true" xbrli:periodType="duration" nillable="true" id="hdsn_CylindersMember" substitutionGroup="xbrli:item"/> |
| <xsd:element name="BalanceSheetClassificationAbstract" type="xbrli:stringItemType" abstract="true" xbrli:periodType="duration" nillable="true" id="hdsn_BalanceSheetClassificationAbstract" substitutionGroup="xbrli:item"/> |
| <xsd:element name="OtherInformationAbstract" type="xbrli:stringItemType" abstract="true" xbrli:periodType="duration" nillable="true" id="hdsn_OtherInformationAbstract" substitutionGroup="xbrli:item"/> |
| <xsd:element name="StockOptionPlanMember" type="dtr-types:domainItemType" abstract="true" xbrli:periodType="duration" nillable="true" id="hdsn_StockOptionPlanMember" substitutionGroup="xbrli:item"/> |
| <xsd:element name="ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePriceAbstract" type="xbrli:stringItemType" abstract="true" xbrli:periodType="duration" nillable="true" id="hdsn_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePriceAbstract" substitutionGroup="xbrli:item"/> |
| <xsd:element name="TwoThousandAndFourteenStockIncentivePlanMember" type="dtr-types:domainItemType" abstract="true" xbrli:periodType="duration" nillable="true" id="hdsn_TwoThousandAndFourteenStockIncentivePlanMember" substitutionGroup="xbrli:item"/> |
| <xsd:element name="TwoThousandAndEighteenStockIncentivePlanMember" type="dtr-types:domainItemType" abstract="true" xbrli:periodType="duration" nillable="true" id="hdsn_TwoThousandAndEighteenStockIncentivePlanMember" substitutionGroup="xbrli:item"/> |
| <xsd:element id="hdsn_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsAggregateIntrinsicValueNonvested" name="SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsAggregateIntrinsicValueNonvested" nillable="true" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="instant" xbrli:balance="debit"/> |
| <xsd:element id="hdsn_LongtermDebtCurrentNetOfOtherDebt" name="LongtermDebtCurrentNetOfOtherDebt" nillable="true" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="instant" xbrli:balance="credit"/> |
| <xsd:element name="TermLoanMember" type="dtr-types:domainItemType" abstract="true" xbrli:periodType="duration" nillable="true" id="hdsn_TermLoanMember" substitutionGroup="xbrli:item"/> |
| <xsd:element name="FCCRMember" type="dtr-types:domainItemType" abstract="true" xbrli:periodType="duration" nillable="true" id="hdsn_FCCRMember" substitutionGroup="xbrli:item"/> |
| <xsd:element name="SwingLineLoanMember" type="dtr-types:domainItemType" abstract="true" xbrli:periodType="duration" nillable="true" id="hdsn_SwingLineLoanMember" substitutionGroup="xbrli:item"/> |
| <xsd:element id="hdsn_FixedChargesCoverageRatio" name="FixedChargesCoverageRatio" nillable="true" type="xbrli:pureItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration"/> |
| <xsd:element id="hdsn_LongTermDebtNonCurrentNetOfOtherDebt" name="LongTermDebtNonCurrentNetOfOtherDebt" nillable="true" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="instant" xbrli:balance="credit"/> |
| <xsd:element id="hdsn_DebtInstrumentLeverageRatioRequired" name="DebtInstrumentLeverageRatioRequired" nillable="true" type="xbrli:pureItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration"/> |
| <xsd:element id="hdsn_OneCustomerMember" name="OneCustomerMember" nillable="true" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" abstract="true" xbrli:periodType="duration"/> |
| <xsd:element id="hdsn_NoCustomerMember" name="NoCustomerMember" nillable="true" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" abstract="true" xbrli:periodType="duration"/> |
| <xsd:element id="hdsn_AmendedAndRestatedRevolvingCreditAndSecurityAgreementMember" name="AmendedAndRestatedRevolvingCreditAndSecurityAgreementMember" nillable="true" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" abstract="true" xbrli:periodType="duration"/> |
| <xsd:element id="hdsn_DebtInstrumentAdditionalPercentagePointsInterest" name="DebtInstrumentAdditionalPercentagePointsInterest" nillable="true" type="dtr-types:percentItemType" substitutionGroup="xbrli:item" xbrli:periodType="instant"/> |
| <xsd:element id="hdsn_TermLoanFacilityMember" name="TermLoanFacilityMember" nillable="true" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" abstract="true" xbrli:periodType="duration"/> |
| <xsd:element id="hdsn_DebtPrepaymentPremiumPercentageYearTwo" name="DebtPrepaymentPremiumPercentageYearTwo" nillable="true" type="dtr-types:percentItemType" substitutionGroup="xbrli:item" xbrli:periodType="instant"/> |
| <xsd:element id="hdsn_DebtPrepaymentPremiumPercentageYearThree" name="DebtPrepaymentPremiumPercentageYearThree" nillable="true" type="dtr-types:percentItemType" substitutionGroup="xbrli:item" xbrli:periodType="instant"/> |
| <xsd:element id="hdsn_DebtPrepaymentPremiumPercentageYearFourAndThereafter" name="DebtPrepaymentPremiumPercentageYearFourAndThereafter" nillable="true" type="dtr-types:percentItemType" substitutionGroup="xbrli:item" xbrli:periodType="instant"/> |
| <xsd:element id="hdsn_CylinderDepositLiabilityPolicyTextBlock" name="CylinderDepositLiabilityPolicyTextBlock" nillable="true" type="dtr-types:textBlockItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration"/> |
| <xsd:element id="hdsn_PropertyLocationAxis" name="PropertyLocationAxis" nillable="true" type="xbrli:stringItemType" substitutionGroup="xbrldt:dimensionItem" abstract="true" xbrli:periodType="duration"/> |
| <xsd:element id="hdsn_PropertyLocationDomain" name="PropertyLocationDomain" nillable="true" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" abstract="true" xbrli:periodType="duration"/> |
| <xsd:element id="hdsn_MinimumAggregateUndrawnLoanAvailability" name="MinimumAggregateUndrawnLoanAvailability" nillable="true" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" xbrli:balance="credit"/> |
| <xsd:element id="hdsn_IncreaseDecreaseInLeaseObligations" name="IncreaseDecreaseInLeaseObligations" nillable="true" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" xbrli:balance="debit"/> |
| <xsd:element id="hdsn_WellsFargoMember" name="WellsFargoMember" nillable="true" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" abstract="true" xbrli:periodType="duration"/> |
| <xsd:element id="hdsn_LineOfCreditFacilityCovenantComplianceMinimumLiquidityToBeDerivedFromAvailability" name="LineOfCreditFacilityCovenantComplianceMinimumLiquidityToBeDerivedFromAvailability" nillable="true" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="instant" xbrli:balance="credit"/> |
| <xsd:element id="hdsn_PeriodForFixedChargeCoverageRatio" name="PeriodForFixedChargeCoverageRatio" nillable="true" type="xbrli:durationItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration"/> |
| <xsd:element id="hdsn_CylinderDepositValue" name="CylinderDepositValue" nillable="true" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" xbrli:balance="debit"/> |
| <xsd:element id="hdsn_CaresActLoanMember" name="CaresActLoanMember" nillable="true" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" abstract="true" xbrli:periodType="duration"/> |
| <xsd:element id="hdsn_PaycheckProtectionProgramMember" name="PaycheckProtectionProgramMember" nillable="true" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" abstract="true" xbrli:periodType="duration"/> |
| <xsd:element id="hdsn_DebtInstrumentInterestDeferralTerm" name="DebtInstrumentInterestDeferralTerm" nillable="true" type="xbrli:durationItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration"/> |
| <xsd:element id="hdsn_TwoThousandAndTwentyStockIncentivePlanMember" name="TwoThousandAndTwentyStockIncentivePlanMember" nillable="true" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" abstract="true" xbrli:periodType="duration"/> |
| <xsd:element id="hdsn_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsAggregateIntrinsicValueNonVested" name="ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsAggregateIntrinsicValueNonVested" nillable="true" type="dtr-types:percentItemType" substitutionGroup="xbrli:item" xbrli:periodType="instant"/> |
| <xsd:element id="hdsn_LesseeOperatingLeaseLiabilityPaymentsDueAfterYearThree" name="LesseeOperatingLeaseLiabilityPaymentsDueAfterYearThree" nillable="true" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="instant" xbrli:balance="credit"/> |
| <xsd:element name="TwentyTwentyOneTermLoanFacilityMember" id="hdsn_TwentyTwentyOneTermLoanFacilityMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" abstract="true"/> |
| <xsd:element name="SecuredOvernightFinancingRateMember" id="hdsn_SecuredOvernightFinancingRateMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" abstract="true"/> |
| <xsd:element name="ApplicableLeverageRationMember" id="hdsn_ApplicableLeverageRationMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" abstract="true"/> |
| <xsd:element name="SecuredOvernightFinancingRatePlusApplicableLeverageRatioMember" id="hdsn_SecuredOvernightFinancingRatePlusApplicableLeverageRatioMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" abstract="true"/> |
| <xsd:element name="PrincipalPaymentAsPercentageOfOriginalPrincipalAmountOfOutstandingTermLoanPerAnnum" id="hdsn_PrincipalPaymentAsPercentageOfOriginalPrincipalAmountOfOutstandingTermLoanPerAnnum" type="dtr-types:percentItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" abstract="false"/> |
| <xsd:element name="DebtPrepaymentPremiumPercentageYearOne" id="hdsn_DebtPrepaymentPremiumPercentageYearOne" type="dtr-types:percentItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" abstract="false"/> |
| <xsd:element name="DebtInstrumentPaymentExcessCashFlowAmount" id="hdsn_DebtInstrumentPaymentExcessCashFlowAmount" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" abstract="false" xbrli:balance="debit"/> |
| <xsd:element name="RevolvingCreditFacilityAmendmentMember" id="hdsn_RevolvingCreditFacilityAmendmentMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" abstract="true"/> |
| <xsd:element name="FirstInLastOutTrancheMember" id="hdsn_FirstInLastOutTrancheMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" abstract="true"/> |
| <xsd:element name="SecuredOvernightFinancingRateAndFirstInLastOutTrancheMember" id="hdsn_SecuredOvernightFinancingRateAndFirstInLastOutTrancheMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" abstract="true"/> |
| <xsd:element name="PrimeCommercialLendingRateOfWellsFargoMember" id="hdsn_PrimeCommercialLendingRateOfWellsFargoMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" abstract="true"/> |
| <xsd:element name="PercentageOfStepdownFromBaselineLevelsFinalRule" id="hdsn_PercentageOfStepdownFromBaselineLevelsFinalRule" type="dtr-types:percentItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" abstract="false"/> |
| <xsd:element name="PercentageOfCumulativeReductionFromBaselineLevelsSubsequentAllowance" id="hdsn_PercentageOfCumulativeReductionFromBaselineLevelsSubsequentAllowance" type="dtr-types:percentItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" abstract="false"/> |
| <xsd:element name="AllocationAllowanceReceivedByCompany" id="hdsn_AllocationAllowanceReceivedByCompany" type="xbrli:integerItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" abstract="false"/> |
| <xsd:element name="AllocationAllowanceReceivedByCompanyAsPercentageOfHydrofluorocarbonsConsumption" id="hdsn_AllocationAllowanceReceivedByCompanyAsPercentageOfHydrofluorocarbonsConsumption" type="dtr-types:percentItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" abstract="false"/> |
| <xsd:element name="NetOperatingLoss" id="hdsn_NetOperatingLoss" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="instant" abstract="false" xbrli:balance="debit"/> |
| <xsd:element name="LongTermDebtFirstInLastOutFilo" id="hdsn_LongTermDebtFirstInLastOutFilo" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="instant" abstract="false" xbrli:balance="credit"/> |
| <xsd:element name="AmortizationOfDeferredFinancingCosts" id="hdsn_AmortizationOfDeferredFinancingCosts" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" abstract="false" xbrli:balance="debit"/> |
| <xsd:element name="AdjustmentsToAdditionalPaidInCapitalIncomeTaxEffectFromShareBasedCompensationNet" id="hdsn_AdjustmentsToAdditionalPaidInCapitalIncomeTaxEffectFromShareBasedCompensationNet" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" abstract="false" xbrli:balance="debit"/> |
| <xsd:element name="ExcessTaxBenefitsFromShareBasedCompensationFinancingActivities" id="hdsn_ExcessTaxBenefitsFromShareBasedCompensationFinancingActivities" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" abstract="false" xbrli:balance="debit"/> |
| <xsd:element name="PaymentsProtectionProgramForgiveness" id="hdsn_PaymentsProtectionProgramForgiveness" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" abstract="false" xbrli:balance="debit"/> |
| </xsd:schema> |