An Introduction to Urban Water and Wastewater Treatment TechnologiesContents1. Contaminants in Water 2. Contaminant Sources and Treatability 3. Best Available Technologies 4. Trend of Development2 21. Contaminants in Water1.1 Target of Water Quality ControlWastewater Discharge RegulationKey point: Protection of human health 3 31.2 Capacity of Water EnvironmentAsimplecalculationCi : Concentration of contaminant iMi : Mass of contaminant i in waterV : Water volumeMi0 : Mass of contaminant i receivedMir :Mass of contaminant i assimilated (removed) by the water body itself (self purification)4 41.2 Capacity of Water EnvironmentWaterqualitycriteriaThisisequivalenttoMirisameasureoftheenvironmentalcapacityCis : Standard for contaminant iMis : Maximum permissible mass of contaminant i in water5 51.3 Water Environmental StandardAmerican standard: Clean Water Act (CWA)uAmbient Water Quality Criteria for the Protection of Human HealthuAquatic Life CriteriauNutrient Criteria6 61.3 Water Environmental StandardAmerican standard: Clean Water Act (CWA)TheNRWQC 2002includesuCriteriaforprioritytoxicpollutants:120items(15forinorganic,105fororganicpollutants)uCriteriafornonprioritypollutants:45itemsuCriteriafororganoleptic(tasteandodor)effects:23itemsDownloadableathttp:/www.epa.gov/waterscience/criteria/ wqcriteria.html7 71.3 Water Environmental StandardChinese standard:EnvironmentalQualityStandardsforSurfaceWater(GB3838-2002)uFundamentalparameters(地表水环境质量标准基本项目标准限值):24itemsuSupplementalparametersforsourcewaterforcommunitywatersupply(集中式生活饮用水地表水源地补充项目标准限值):5itemsuSpecificparametersforsourcewaterforcommunitywatersupply(集中式生活饮用水地表水源地特定项目标准限值):80items8 8表1地表水环境质量标准基本项目标准限值(单位:mg/L)9 9表1地表水环境质量标准基本项目标准限值(单位:mg/L)1010表1地表水环境质量标准基本项目标准限值(单位:mg/L)1111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)1212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)1313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)1414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)15151.4 Pollutants of Public ConcernIndicative parametersuSuspendedsolids:SSuDissolvedsolids:TDS(salinity)uOrganicsubstances:COD,BOD,TOC,UVuDissolvedoxygen:DOuAcidity:pHNutrientsuNitrogen:TN,NH3-N,NO3-N,NO2-NuPhosphorous:TP,Portho,Ppoly,Poranic16161.4 Pollutants of Public ConcernSynthetic organic chemicals (SOCs)uIndustrialproductssuchasPCBs(Polychlorinatedbiphenyls)uIndustrialbyproductssuchasDioxinuPesticidesandherbicidesDBP precursorsuNaturalorganicmatter(NOM)suchashumicacidsetc.Persistent organic pollutants (POPs)uDDT,PCBs,PAHs,Hexachlorobenzene,Dioxins,Furans17171.4 Pollutants of Public ConcernEndocrine disruptive chemicals (EDCs) uHeavymetalssuchasCr,Pbetc.uPCBs,hormones,dioxinsuOrgano-chlorinatedpesticidesMicroorganismsuGiardiauCryptosporidiumuVirusesandbacteria18182. Contaminant Sources and Treatability2.1 Contaminant SourcesPoint sources:Sourcesofpollutantsfromadiscretelocationsuchasapipe,tank,pit,orditch.Non-point sources:Sourceofpollutantsfromanumberofpointsthatarespreadoutanddifficulttoidentifyandcontrol.Non-pointsourcesattributeagreatdealtowaterpollution:lNutrients,pesticides,NOMlCertainPOPsandEDCs19192.2 Treatability of PollutantsThetreatabilityofpollutantsdependsontheirSizelSuspendedlColloidallSolubleChemical propertieslOrganiclInorganicBiodegradabilitylBiodegradablelBio-non-degradable2020Water quality and treatability matrix2121Domestic wastewater as an exampleMethodsofpollutantsclassificationuSuspended and soluble:usinga0.45mmfilteruSettleable and non-settleable:plainsettlingfor2hoursuCoagulable and non-coagulable:coagulationandsettlinguSecondary treatment:activatedsludgeprocess(oxidationditch)222223232.3 Limitation of Conventional TreatmentConventional treatmentuTypicalprocessforwatertreatment:CoagulationsedimentationfiltrationchlorinationuTypicalprocessforwastewatertreatment(activatedsludgeprocess):Screeningprimarysettlingbiologicalunitsecondarysettlingchlorination24242.3 Limitation of Conventional TreatmentPollutants that can be removeduSuspendedsolidsuColloidalmatteruBiodegradableorganicmatteruBacteriaandvirusesPollutants that cannot be removeduMostofthedissolvedsolidsuBio-non-degradableorganicmatteruChlorinepersistentmicroorganisms(e.g.Cryptosporidium)25253. Best Available Technologies3.1 Strategic Considerations on the Selection of Available TechnologiesuConventionaltechnologiesarefundamentaltechnologiesandtheirenhancementshouldbethefirstchoiceuConversionofthepropertyofpollutantsissometimesmoreimportantthanacompleteremovalofthepollutantsuCombinationofdifferenttechnologiesisthekeyforeffectiveremovalofpollutants26263.2 Enhancement of Conventional TechnologiesEnhanced coagulationuFortheremovalofNOMindrinkingwatertreatmentuFortheenhancementofprimarytreatmentinwastewatertreatmentTakingNOMremovalasanexampleUSEPA Enhanced Coagulation Rule27273.2 Enhancement of Conventional TechnologiesEnhanced coagulationuRequirementsforenhancedcoagulation:EnhancedcoagulationrequiredasTOC2mg/LuStep1:percentremovalrequirements2828uStep2:0.3/10slope2929upHadjustmentisthekeypoint30303.2 Enhancement of Conventional TechnologiesEnhanced filtrationuForthesafeguardofdrinkingwaterqualityespeciallythecontrolofGiardiaandCryptosporidiumlGiardialamblia:cystsize8-12mmx7-10mmlCryptosporidiumparvum:oosystsize4.5-5mmuFortertiarywastewatertreatmenttoacquirehighqualityeffluent31313.2 Enhancement of Conventional TechnologiesEnhanced filtrationuRelationshipbetweenturbidityandparticlesize3232ExampleofturbidityandCryptosporidiumoocystdata33333.2 Enhancement of Conventional TechnologiesEnhanced filtrationuIronoxide-coatedmediaforNOMsorptionandparticulatefiltrationuIronandaluminumhydroxide-coatedmediafortheremovalofCryptosporidium3434Breakthrough curves for NOM sorption onto coated sand 3535Zeta potential of uncoated sand and sand coated with iron and aluminum hydroxide3636Improvement of the removal of Cryptosporidium oocysts in sand filters37373.2 Enhancement of Conventional TechnologiesEnhancement of biological processuFluidizedpelletbed(FPB)bioreactorasanexamplethroughacombinationofphysicochemicalprocessandbiologicalprocesslHRTreducedtolessthan1hourlPrimarysettlingandsecondarysettlingomittedlOrganicremovalequivalenttoactivatedsludgeprocesslHighTPremovalachieved3838Flow diagram of the FPB bioreactor3939 Pellets (granule sludge) formed in the bioreactor SEM image of microbes on the surface of the pellets 4040 Distribution of aerobic and anaerobic bacteria4141 Removal of SS, COD, TP and TN by the bioreactor42423.3 Ozone and Advanced Oxidation ProcessesReactivity of ozone in aqueous solutionInanaqueoussolution,ozonemayactonvariouscompoundsbylDirectreactionwiththemolecularozonelIndirectreactionwiththeradicalspeciesthatareformedwhenozonedecomposesinwaterAdvanced oxidationOxidationbyfreeradicalreaction4343Pathways of ozonationPseudo first-order kinetic equation of ozone decomposition4444Ozone decomposition process4545Initiators, promotors, and inhibitors of free-radical reactionsuInitiators:thecompoundscapableofinducingtheformationofasuperoxideionO2-fromanozonemoleculeuPromotors:allorganicandinorganicmoleculescapableofregeneratingtheO2-superoxideanionfromthehydroxylradicaluInhibitors:compoundscapableofconsumingOHradicalswithoutregeneratingthesuperoxideanionO2-4646Mechanism of ozone decomposition4747Ozone decomposition process by hydroperoxide ions4848Ozone decomposition process by UV radiation49493.3 Ozone and Advanced Oxidation ProcessesOzonation of synthetic organic chemicalsTwoozonolysispathwaysofozonation:uDirectattackbyelectrophilicordipolarcycloadditionuIndirectattackbyfree radicalsproducedbyreactionwithwaterandwaterconstituents5050Kinetics of ozonation of dissolved organic micropollutantsuOzonationpathwaysuLet5151uTheOHradicalsaregeneratedbyozoneattackonorganicandinorganicinitiators,andthereexistsarelationasuThetotaloxidationrateoftheparticularsubstrateicanbewrittenas5252Characteristics of ozonation of organic compoundsuDecreaseofaromaticityuUnsaturatedstructuretosaturatedstructureuGenerationofintermediateproductsuTotaldegradationoftenneedsveryhighozonedoseandtakeslongertime5353 Example: Ozonation of aromatic compounds54543.3 Ozone and Advanced Oxidation ProcessesOzonation of natural organic matter (NOM)Aquatichumicsubstances(AHS):uIsolationmethod:microfiltrationofthewaterandadsorptionoforganicsonXAD-8resinatpH=2,followedbyNaOHelutionandseparationbyprecipitationatpH=1.uTwomaingroups:Humic acidprecipitatedfractionFulvic acidremainingpartinthesolution5555Possible reaction of zone consumption in a natural aquatic environment d inhibitorsi initiatorsp promotorss - scavengers5656Ozone action on AHS5757The effects of ozonation on AHSuFormationofhydroxyl,carbonylandcarboxylgroups;uIncreaseofpolarityandhydrophilicity;uLossofdoublebondsandaromaticity;uShiftinthemolecularweightdistributiontowardlower-molecular-weightcompounds.5858Py-GC-MS analysis results5959THMs and HPLC analysis results6060Specific UV adsorption (SUVA) as a parameter showing the biodegradability of AHSuTOCorDOC:totalamountoforganiccarbonuUV254:concentrationoforganicswithunsaturatedstructureuSUVA:UV-to-TOCratiowhichrepresentsthefractionofunsaturatedfunctionalgroupsinunitconcentrationoforganicmatteruHighSUVAvalue:lessbiodegradableuLowSUVAvalue:morebiodegradable61613.4 Membrane TechnologiesSpectrum of impurities in water and applicable filtration processes 62623.4 Membrane TechnologiesMembrane operation63633.4 Membrane TechnologiesPressure-driven membrane operationuRO:atleasttwicetheosmoticpressuremustbeexerted5to8MPaforseawateruNF:osmoticbackpressuremuchlowerthanROtypically0.5to1.5MPauUF:operatingpressure50to500kPauMF:operatingpressuresimilartoUF64643.4 Membrane TechnologiesPermeation behavioruDarcyslawuToaccountfortheeffectsofosmoticpressure65653.4 Membrane TechnologiesReduction in Permeate FluxRc:resistanceofconcentrationboundarylayerRcp:resistanceofconcentration-polarizationlayerD:diffusivity66663.4 Membrane TechnologiesReduction in Permeate FluxTheaccumulationofmaterialson,in,andnearamembraneinthepresenceofacrossflowReductionsinpermeatefluxovertime67673.4 Membrane TechnologiesMechanism of membrane foulinguCakeformationuPoreblockageuAdsorptivefoulinguBiofoulingSEMimageofabiofilmformedonamembrane6868Conventional UF or MF process6969Conventional NF or RO process70703.4 Membrane TechnologiesMembrane bioreactor (MBR)uPrincipleofMBR(a) MBR(b) Membrane for tertiary treatment71713.4 Membrane TechnologiesMembrane bioreactor (MBR)uMBRconfiguration(a) Recirculated MBR(b) Integrated MBR72723.4 Membrane TechnologiesMembrane bioreactor (MBR)uAdvantagesofMBRlGreaterbiomassconcentrationandgreaterloadslHighremovalefficiencylLesssludgeproductionlGreaterreliabilityandflexibilityofapplicationlAbilitytoabsorbvariationsandfluctuationsintheappliedhydraulicandorganicloadlCompletecontrolofthesludgeagetoallowthedevelopmentofslow-growingmicroorganisms(suchasnitrifyingbacteria)73734. Trend of Development4.1 Integration of Water and Wastewater SystemFundamental considerationsuWatersupplyandwastewatersystemsaresubsystemsintheseriesofurbanmetabolicsystemofwateruWatersupplyaccordingtothepurposesofuseregardingbothquantityandqualityuDesignofwaterandwastewatersystemsasonecomprehensivewatersystem7474Future urban water system with application of membrane technology75754.2 Decentralized Systems for Wastewater Treatment and ReusePhilosophy of decentralizationuNon-mixinglGrey water:Largevolumes,CODdiluted,littlenutrients,pathogens,nopharmaceuticals,personalcareproductslBlack water:Littlevolumes,possibilitiestominimisethemevenfurther,highCODandnutrients,pathogens,pharmaceuticalsandhormonesuSeparatetreatmentlTreatmentdependsontheobjectiveuRecoveryofusefulresourceslWater,energy,fertilizer76764.3 Control of Micropollutants in Water and Wastewater TreatmentuControlofpollutantsourceuUtilizationofhybridprocesslAdvancedoxidationandcarbonadsorptionuUtilizationofhybridmembraneprocesslMembrane-powderedactivatedcarbonreactorlIonexchangemembranereactor7777