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[HJ3~NN݌$` (#` (# Ќ  b G( 88"b & y OtherConsiderations:  R! 'yR9P  ForPMapplications,wetscrubbersgeneratewasteintheformofaslurry.Thiscreatestheneedforbothwastewatertreatmentandsolidwastedisposal.Initially,theslurryistreatedtoseparatethesolidwastefromthewater.Thetreatedwatercanthenbereusedordischarged.Oncethewaterisremoved,theremainingwastewillbeintheformofasolidorsludge.Ifthesolidwasteisinertandnontoxic,itcangenerallybe_landfilled_.Hazardouswasteswillhavemorestringentproceduresfordisposal.Insomecases,thesolidwastemayhavevalueandcanbesoldorrecycled(EPA,1998).Forgasabsorption,thewaterorothersolventmustbetreatedtoremovethecapturedpollutantfromthesolution.Theeffluentfromthecolumnmayberecycledintothesystemandusedagain.Thisisusuallythecaseifthesolventiscostly(e.g.,hydrocarbonoils,causticsolutions).Initially,therecyclestreammaygotoawastetreatmentsystemtoremovethepollutantsorthereactionproduct.Makeupsolventmaythenbeaddedbeforetheliquidstreamreentersthecolumn(EPA,1996).For_FGD_Ԁapplications,theslurrycombineswiththeSO2ladenwastegastoformawasteslurryinthebottom $0 ofthescrubber.Thesludgeisremovedfromthescrubberand,dependinguponthereagentorsorbentusedtoreactwiththeSO2,thewastereactedsludgeisdisposedof,recycledorregenerated,or,insomecases, G&!2 asalableproduct.Forslurrieswhichproducecalciumsulfateandsulfite,oxidizingthewastesludgeresultsingypsum.Gypsumisapreferredproductbecauseitcanbemarketedandalsobecauseofitssuperior_dewatering_Ԁcharacteristics.Mostscrubbersareoperatedwithouttheoxidizingstepandthewastesludgemustbe_dewatered_Ԁanddisposedofproperly.Someslurriescanberegeneratedandusedagain,butfewsuchsystemsareinuseduetohighenergycostsassociatedwiththeregenerationofthereagent(_Sondreal_,1993;_Soud_,etal.,1993;Merrick,1989).Configuringacontroldevicethatoptimizescontrolofmorethanonepollutantoftendoesnotachievethehighestcontrolpossibleforanyofthepollutantscontrolledalone.Forthisreason,wastegasflowswhichcontainmultiplepollutants(e.g.,PMandSO2,orPMandinorganicgases)aregenerallycontrolledwith {.)< multiplecontroldevices,occasionallymorethanonetypeofwetscrubber(_EC_/R,1996). M/*= P_UU References: _  _Avallone_,1996. MarksStandardHandbookforMechanicalEngineers,editedbyEugene_Avallone_ԀandTheodore_Baumeister_,10thEdition,_McGraw_ԄHill,NewYork,NY,1996. )y _AWMA_,1992.Air&WasteManagementAssociation,AirPollutionEngineeringManual,Van_Nostrand_  Reinhold,NewYork.Cooper,1994.DavidCooperandF.Alley,AirPollutionControl:ADesignApproach,2ndEdition, C  _Waveland_ԀPress,ProspectHeights,IL,1994._EC_/R,1996._EC_/R,Inc., EvaluationofFineParticulateMatterControlTechnology:FinalDraft,preparedforU.S.EPA,IntegratedPolicyandStrategiesGroup,Durham,NC,September,1996.EPA,1981.U.S.EPA,OfficeofAirQualityPlanningandStandards, ControlTechnologiesforSulfurOxideEmissionfromStationarySources,SecondEdition,ResearchTrianglePark,NC,April,1981.EPA,1991.U.S.EPA,OfficeofResearchandDevelopment, ControlTechnologiesforHazardousAirPollutants,EPA/625/691/014,Washington,D.C.,June.EPA,1992.U.S.EPA,OfficeofAirQualityPlanningandStandards, ControlTechnologiesforVolatileOrganicCompoundEmissionsfromStationarySources,EPA453/R92018,ResearchTrianglePark,NC,December,1992EPA,1993.U.S.EPA,OfficeofAirQualityPlanningandStandards, ChromiumEmissionsfromChromiumElectroplatingandChromicAcidAnodizingOperations!BackgroundInformationforProposedStandards,EPA453/R93030a,ResearchTrianglePark,NC,July1993.EPA,1996.U.S.EPA,OfficeofAirQualityPlanningandStandards, _OAQPS_ԀControlCostManual,FifthEdition,EPA453/B96001,ResearchTrianglePark,NCFebruary.EPA,1998.U.S.EPA,OfficeofAirQualityPlanningandStandards, StationarySourceControlTechniquesDocumentforFineParticulateMatter,EPA452/R97001,ResearchTrianglePark,NC,October.Merrick,1989.DavidMerrickandJanVernon, ReviewofFlueGas_Desulphurization_ԀSystems,ChemistryandIndustry,February6,1989._Sondreal_,1993.EverettA._Sondreal_, CleanUtilizationofLowRankCoalsforLowCostPowerGeneration,from CleanandEfficientUseofCoal:TheNewEraforLowRankCoal,OrganizationforEconomicCoOperationandDevelopment/InternationalEnergyAgency,Paris,France,1993._Soud_,etal.,1993._Hermine_ԀN._Soud_,_Mitsuru_Ԁ_Takeshita_,andIreneM.Smith, _FGC_ԀSystemsandInstallationsforCoalFiredPlantsfrom _Desulfurization_Ԁ3,InstitutionofChemicalEngineers,Warwickshire,UK,1993.