城市污水处理技术（英文课件） 77页

'AnIntroductiontoUrbanWaterandWastewaterTreatmentTechnologies Contents1.ContaminantsinWater2.ContaminantSourcesandTreatability3.BestAvailableTechnologies4.TrendofDevelopment2 1.ContaminantsinWater1.1TargetofWaterQualityControlWastewaterDischargeRegulationKeypoint:Protectionofhumanhealth3 1.2CapacityofWaterEnvironmentAsimplecalculationCi:ConcentrationofcontaminantiMi:MassofcontaminantiinwaterV:WatervolumeMi0:MassofcontaminantireceivedMir:Massofcontaminantiassimilated(removed)bythewaterbodyitself(selfpurification)4 1.2CapacityofWaterEnvironmentWaterqualitycriteriaThisisequivalenttoMirisameasureoftheenvironmentalcapacityCis:StandardforcontaminantiMis:Maximumpermissiblemassofcontaminantiinwater5 1.3WaterEnvironmentalStandardAmericanstandard:CleanWaterAct(CWA)AmbientWaterQualityCriteriafortheProtectionofHumanHealthAquaticLifeCriteriaNutrientCriteria6 1.3WaterEnvironmentalStandardAmericanstandard:CleanWaterAct(CWA)TheNRWQC2002includesCriteriaforprioritytoxicpollutants:120items(15forinorganic,105fororganicpollutants)Criteriafornonprioritypollutants:45itemsCriteriafororganoleptic(tasteandodor)effects:23itemsDownloadableathttp://www.epa.gov/waterscience/criteria/wqcriteria.html7 1.3WaterEnvironmentalStandardChinesestandard:EnvironmentalQualityStandardsforSurfaceWater(GB3838-2002)Fundamentalparameters(地表水环境质量标准基本项目标准限值):24itemsSupplementalparametersforsourcewaterforcommunitywatersupply(集中式生活饮用水地表水源地补充项目标准限值):5itemsSpecificparametersforsourcewaterforcommunitywatersupply(集中式生活饮用水地表水源地特定项目标准限值):80items8 表1地表水环境质量标准基本项目标准限值(单位:mg/L)9 表1地表水环境质量标准基本项目标准限值(单位:mg/L)10 表1地表水环境质量标准基本项目标准限值(单位:mg/L)11 表2集中式生活饮用水地表水源地补充项目标准限值(单位：mg/L)12 表3集中式生活饮用水地表水源地特定项目标准限值(单位：mg/L)13 表3集中式生活饮用水地表水源地特定项目标准限值(单位：mg/L)14 表3集中式生活饮用水地表水源地特定项目标准限值(单位：mg/L)15 1.4PollutantsofPublicConcernIndicativeparametersSuspendedsolids:SSDissolvedsolids:TDS(salinity)Organicsubstances:COD,BOD,TOC,UV…Dissolvedoxygen:DOAcidity:pHNutrientsNitrogen:TN,NH3-N,NO3-N,NO2-N…Phosphorous:TP,Portho,Ppoly,Poranic…16 1.4PollutantsofPublicConcernSyntheticorganicchemicals(SOCs)IndustrialproductssuchasPCBs(Polychlorinatedbiphenyls)IndustrialbyproductssuchasDioxinPesticidesandherbicidesDBPprecursorsNaturalorganicmatter(NOM)suchashumicacidsetc.Persistentorganicpollutants(POPs)DDT,PCBs,PAHs,Hexachlorobenzene,Dioxins,Furans…17 1.4PollutantsofPublicConcernEndocrinedisruptivechemicals(EDCs)HeavymetalssuchasCr,Pbetc.PCBs,hormones,dioxinsOrgano-chlorinatedpesticidesMicroorganismsGiardiaCryptosporidiumVirusesandbacteria18 2.ContaminantSourcesandTreatability2.1ContaminantSourcesPointsources:Sourcesofpollutantsfromadiscretelocationsuchasapipe,tank,pit,orditch.Non-pointsources:Sourceofpollutantsfromanumberofpointsthatarespreadoutanddifficulttoidentifyandcontrol.Non-pointsourcesattributeagreatdealtowaterpollution:Nutrients,pesticides,NOMCertainPOPsandEDCs19 2.2TreatabilityofPollutantsThetreatabilityofpollutantsdependsontheirSizeSuspendedColloidalSolubleChemicalpropertiesOrganicInorganicBiodegradabilityBiodegradableBio-non-degradable20 Waterqualityandtreatabilitymatrix21 DomesticwastewaterasanexampleMethodsofpollutantsclassificationSuspendedandsoluble:usinga0.45mmfilterSettleableandnon-settleable:plainsettlingfor2hoursCoagulableandnon-coagulable:coagulationandsettlingSecondarytreatment:activatedsludgeprocess(oxidationditch)22 23 2.3LimitationofConventionalTreatmentConventionaltreatmentTypicalprocessforwatertreatment:Coagulation–sedimentation–filtration–chlorinationTypicalprocessforwastewatertreatment(activatedsludgeprocess):Screening–primarysettling–biologicalunit–secondarysettling–chlorination24 2.3LimitationofConventionalTreatmentPollutantsthatcanberemovedSuspendedsolidsColloidalmatterBiodegradableorganicmatterBacteriaandvirusesPollutantsthatcannotberemovedMostofthedissolvedsolidsBio-non-degradableorganicmatterChlorinepersistentmicroorganisms(e.g.Cryptosporidium)25 3.BestAvailableTechnologies3.1StrategicConsiderationsontheSelectionofAvailableTechnologiesConventionaltechnologiesarefundamentaltechnologiesandtheirenhancementshouldbethefirstchoiceConversionofthepropertyofpollutantsissometimesmoreimportantthanacompleteremovalofthepollutantsCombinationofdifferenttechnologiesisthekeyforeffectiveremovalofpollutants26 3.2EnhancementofConventionalTechnologiesEnhancedcoagulationFortheremovalofNOMindrinkingwatertreatmentFortheenhancementofprimarytreatmentinwastewatertreatmentTakingNOMremovalasanexample–USEPAEnhancedCoagulationRule27 3.2EnhancementofConventionalTechnologiesEnhancedcoagulationRequirementsforenhancedcoagulation:EnhancedcoagulationrequiredasTOC>2mg/LStep1:percentremovalrequirements28 Step2:0.3/10slope29 pHadjustmentisthekeypoint30 3.2EnhancementofConventionalTechnologiesEnhancedfiltrationForthesafeguardofdrinkingwaterqualityespeciallythecontrolofGiardiaandCryptosporidiumGiardialamblia:cystsize8-12mmx7-10mmCryptosporidiumparvum:oosystsize4.5-5mmFortertiarywastewatertreatmenttoacquirehighqualityeffluent31 3.2EnhancementofConventionalTechnologiesEnhancedfiltrationRelationshipbetweenturbidityandparticlesize32 ExampleofturbidityandCryptosporidiumoocystdata33 3.2EnhancementofConventionalTechnologiesEnhancedfiltrationIronoxide-coatedmediaforNOMsorptionandparticulatefiltrationIronandaluminumhydroxide-coatedmediafortheremovalofCryptosporidium34 BreakthroughcurvesforNOMsorptionontocoatedsand35 Zetapotentialofuncoatedsandandsandcoatedwithironandaluminumhydroxide36 ImprovementoftheremovalofCryptosporidiumoocystsinsandfilters37 3.2EnhancementofConventionalTechnologiesEnhancementofbiologicalprocessFluidizedpelletbed(FPB)bioreactorasanexamplethroughacombinationofphysicochemicalprocessandbiologicalprocessHRTreducedtolessthan1hourPrimarysettlingandsecondarysettlingomittedOrganicremovalequivalenttoactivatedsludgeprocessHighTPremovalachieved38 FlowdiagramoftheFPBbioreactor39 Pellets(granulesludge)formedinthebioreactorSEMimageofmicrobesonthesurfaceofthepellets40 Distributionofaerobicandanaerobicbacteria41 RemovalofSS,COD,TPandTNbythebioreactor42 3.3OzoneandAdvancedOxidationProcessesReactivityofozoneinaqueoussolutionInanaqueoussolution,ozonemayactonvariouscompoundsbyDirectreactionwiththemolecularozoneIndirectreactionwiththeradicalspeciesthatareformedwhenozonedecomposesinwaterAdvancedoxidationOxidationbyfreeradicalreaction43 PathwaysofozonationPseudofirst-orderkineticequationofozonedecomposition44 Ozonedecompositionprocess45 Initiators,promotors,andinhibitorsoffree-radicalreactionsInitiators:thecompoundscapableofinducingtheformationofasuperoxideionO2-fromanozonemoleculePromotors:allorganicandinorganicmoleculescapableofregeneratingtheO2-superoxideanionfromthehydroxylradicalInhibitors:compoundscapableofconsumingOHradicalswithoutregeneratingthesuperoxideanionO2-46 Mechanismofozonedecomposition47 Ozonedecompositionprocessbyhydroperoxideions48 OzonedecompositionprocessbyUVradiation49 3.3OzoneandAdvancedOxidationProcessesOzonationofsyntheticorganicchemicalsTwoozonolysispathwaysofozonation:DirectattackbyelectrophilicordipolarcycloadditionIndirectattackbyfreeradicalsproducedbyreactionwithwaterandwaterconstituents50 KineticsofozonationofdissolvedorganicmicropollutantsOzonationpathwaysLet51 TheOHradicalsaregeneratedbyozoneattackonorganicandinorganicinitiators,andthereexistsarelationasThetotaloxidationrateoftheparticularsubstrateicanbewrittenas52 CharacteristicsofozonationoforganiccompoundsDecreaseofaromaticityUnsaturatedstructuretosaturatedstructureGenerationofintermediateproductsTotaldegradationoftenneedsveryhighozonedoseandtakeslongertime53 Example:Ozonationofaromaticcompounds54 3.3OzoneandAdvancedOxidationProcessesOzonationofnaturalorganicmatter(NOM)Aquatichumicsubstances(AHS):Isolationmethod:microfiltrationofthewaterandadsorptionoforganicsonXAD-8resinatpH=2,followedbyNaOHelutionandseparationbyprecipitationatpH=1.Twomaingroups:Humicacid–precipitatedfractionFulvicacid–remainingpartinthesolution55 Possiblereactionofzoneconsumptioninanaturalaquaticenvironmentd–inhibitorsi–initiatorsp–promotorss-scavengers56 OzoneactiononAHS57 TheeffectsofozonationonAHSFormationofhydroxyl,carbonylandcarboxylgroups;Increaseofpolarityandhydrophilicity;Lossofdoublebondsandaromaticity;Shiftinthemolecularweightdistributiontowardlower-molecular-weightcompounds.58 Py-GC-MSanalysisresults59 THMsandHPLCanalysisresults60 SpecificUVadsorption(SUVA)asaparametershowingthebiodegradabilityofAHSTOCorDOC:totalamountoforganiccarbonUV254:concentrationoforganicswithunsaturatedstructureSUVA:UV-to-TOCratiowhichrepresentsthefractionofunsaturatedfunctionalgroupsinunitconcentrationoforganicmatterHighSUVAvalue:lessbiodegradableLowSUVAvalue:morebiodegradable61 3.4MembraneTechnologiesSpectrumofimpuritiesinwaterandapplicablefiltrationprocesses62 3.4MembraneTechnologiesMembraneoperation63 3.4MembraneTechnologiesPressure-drivenmembraneoperationRO:atleasttwicetheosmoticpressuremustbeexerted–5to8MPaforseawaterNF:osmoticbackpressuremuchlowerthanRO–typically0.5to1.5MPaUF:operatingpressure50to500kPaMF:operatingpressuresimilartoUF64 3.4MembraneTechnologiesPermeationbehaviorDarcy’slawToaccountfortheeffectsofosmoticpressure65 3.4MembraneTechnologiesReductioninPermeateFluxRc:resistanceofconcentrationboundarylayerRcp:resistanceofconcentration-polarizationlayerD:diffusivity66 3.4MembraneTechnologiesReductioninPermeateFluxTheaccumulationofmaterialson,in,andnearamembraneinthepresenceofacrossflowReductionsinpermeatefluxovertime67 3.4MembraneTechnologiesMechanismofmembranefoulingCakeformationPoreblockageAdsorptivefoulingBiofoulingSEMimageofabiofilmformedonamembrane68 ConventionalUForMFprocess69 ConventionalNForROprocess70 3.4MembraneTechnologiesMembranebioreactor(MBR)PrincipleofMBR(a)MBR(b)Membranefortertiarytreatment71 3.4MembraneTechnologiesMembranebioreactor(MBR)MBRconfiguration(a)RecirculatedMBR(b)IntegratedMBR72 3.4MembraneTechnologiesMembranebioreactor(MBR)AdvantagesofMBRGreaterbiomassconcentrationandgreaterloadsHighremovalefficiencyLesssludgeproductionGreaterreliabilityandflexibilityofapplicationAbilitytoabsorbvariationsandfluctuationsintheappliedhydraulicandorganicloadCompletecontrolofthesludgeagetoallowthedevelopmentofslow-growingmicroorganisms(suchasnitrifyingbacteria)73 4.TrendofDevelopment4.1IntegrationofWaterandWastewaterSystemFundamentalconsiderationsWatersupplyandwastewatersystemsaresubsystemsintheseriesofurbanmetabolicsystemofwaterWatersupplyaccordingtothepurposesofuseregardingbothquantityandqualityDesignofwaterandwastewatersystemsasonecomprehensivewatersystem74 Futureurbanwatersystemwithapplicationofmembranetechnology75 4.2DecentralizedSystemsforWastewaterTreatmentandReusePhilosophyofdecentralizationNon-mixingGreywater:Largevolumes,CODdiluted,littlenutrients,pathogens,nopharmaceuticals,personalcareproductsBlackwater:Littlevolumes,possibilitiestominimisethemevenfurther,highCODandnutrients,pathogens,pharmaceuticalsandhormonesSeparatetreatmentTreatment–dependsontheobjectiveRecoveryofusefulresourcesWater,energy,fertilizer76 4.3ControlofMicropollutantsinWaterandWastewaterTreatmentControlofpollutantsourceUtilizationofhybridprocessAdvancedoxidationandcarbonadsorptionUtilizationofhybridmembraneprocessMembrane-powderedactivatedcarbonreactorIonexchangemembranereactor……77'