9环境工程专业英语unit-14-15

环境科学与工程专业英语SpecializedEnglishforenvironmentalscienceandengineering化学化工学院贺薇PART3WATERANDWASTEWATERTREATMENTUnit14WaterPurificationUnit15WaterTreatmentProcessesscreening['skri:niŋ]v.筛（煤、矿石等）n.放映，播放；筛查coagulationflocculationSedimentationsedimentationbasin沉淀池filtration[filtreiʃən]n.过滤；滤除disinfectionNewWordsandPhrasesCoagulation[kəʊæɡju'leɪʃn]n.凝结，凝结物coagulatevt.&vi.凝固；使结块，使变稠adj.凝固的，凝结的，凝聚的coagulant[kəʊ'ægjələnt]n.凝结剂沉淀物precipitate;deposition;sediment;sedimentation;subsidence浓缩,冷凝condense;condensationcolloidal[kə'lɔidl]adj.带相同电荷的胶粒不能紧密靠近，它们不能聚集成较大的颗粒。Similarlychargedcolloidalparticlescannotcometogethercloselytoagglomerateintolargerparticles.colloid['kɔlɔid]n.colloidgold胶态金水体所含物质主要有：悬浮物、胶体物质等等。Mainsubstancescontainedinrawwatersaresuspensions,colloidsubstances,etc.desalination[di:sæli'neiʃən]脱盐〔作用〕，去盐〔作用〕saline['seili:n]①〔含〕盐的；②盐水salinity[sə'linəti]n.盐分，盐度；盐浓度；盐份Physical物理方法Sedimentation(Clarification)沉淀Screening格栅Aeration曝气Filtration过滤FlotationandSkimming浮选Degasification脱气Equalization均和BackgroundIntroductionChemical化学方法Chlorination氯化Ozonation臭氧处理Neutralization中和Coagulation絮凝Adsorption吸附IonExchange离子交换长江师范学院化学化工学院Biological生物方法Aerobic好氧法ActivatedSludgeTreatmentMethod活性污泥法TricklingFiltration滴滤法OxidationPonds氧化塘Lagoons泻湖(氧化塘)AerobicDigestion需氧消化Anaerobic厌氧法AnaerobicDigestion厌氧消化SepticTanks化粪池WatertreatmentfordomesticandcommercialusesCriteriaCausingPollutantCorrespondingremovalmeasuresFreeofodorOdorousgasesAerationtoremoveodorgasesFreeofturbidityParticlesAdditionofFe3+andAl3+totrapparticlesLowBODOrganicmaterialsBacteriametabolismLownutrientloadingDissolvedN,PinorganicChemicalprecipitationNH3strippingFreeofdiseasecausingagentsmicroorganismsAdditionofdisinfectantsPrimarywatertreatmentPrimarytreatment:RemovesolidsbyscreeningandsettlingThesewageispassedthroughascreentoremovelargepiecesofdebris(e.g.sticks,stones,rags,andplasticbags).Next,thesewageentersagritchamber,wherethewaterflowisslowedjustenoughtoallowcoarsesandandgraveltosettleoutonthebottom.Waterthenentersthesedimentationtank,itsflowrateisfurtherdecreasedtopermitsuspendedsolidstosettleoutasrawsludge.Primarywatertreatment(Continued)Ca(OH)2andAl2(SO4)3areoftenaddedtospeedupthesedimentationprocess.3Ca(OH)2+Al2(SO4)32Al(OH)3+3CaSO4Al(OH)3isagelatinousprecipitationthatsettlesoutslowly,carryingsuspendedmaterialandbacteriawithit.Oilymaterialfloatstothesurfaceandisskimmedoff.Thegritiscollectedanddisposedinlandfill.Therawsludge:Oldway:incinerated,disposedinlandfillordumpedatsea.Newway:compostedtoproduceanutrientrichbacteria-freematerialforuseasfertilizer.PrimarytreatmentInoldersewage-treatmentplants,thewaterafterprimarytreatmentisoftenchlorinatedtokillpathogensandthendischargedintoanaturalwaterway.Thedischargedwateratthisstagestillcontainsalargeamountofoxygen-consumingwastes,whichmaydepletedissolvedoxygeninthewaterwayandcauseeutrophication.SecondarytreatmentSecondarytreatment,alsocalledbiologicaltreatment:UsebacteriatobreakdownorganiccompoundstoCO2.Amixtureoforganisms–termedactivatedsludge–isaddedtothesewageeffluent.Airoroxygenisvigorouslybubbledthroughpipesintotheeffluent.TheaerobicbacteriadigesttheorganicmaterialandbreakitdownintoCO2andwater.Thebacteriaandanyremainingundecomposedmaterialarereturnedtotheaerationtankandreused.ActivatedsludgeprocessSecondarytreatmentofmunicipalwastewaterMostmunicipalplantschlorinatedthewateraftersecondarytreatmentandthenreleaseitintowaterways.Thedischargedwateratthisstagehas~90%oftheoriginalorganicmatterremoved,butover50%ofN,Pspeciesremains,andmetalionsandmanysyntheticorganiccompoundsareincompletelyremoved.(eutrophication)TertiarytreatmentRemoveNandPnutrients.Premovalbyprecipitationwithlime3PO43-+CaO(lime)Ca5(PO4)3(OH)Phosphatecanalsoberemovedbymicroorganismsthatabsorbphosphate.NH4+removalbyammoniastripping.NH4++OH-=NH3+H2O(ExcessOH-fromlime)AlternativeNH4+removal:nitrifyingbacteriaconvertNH4+toNO3-followedbydenitrifyingbacteriatoconvertNO3-toN2.RemoveorganicsthroughfiltrationbyactivatedcarbonTertiarytreatment,alsocalledadvancedwastetreatment,includesavarietyofprocessesperformedontheeffluentfromsecondarywastetreatment.HydroxyapetiteTertiarytreatmentofmunicipalwastewaterPerformanceofprimaryandsecondarystagesofsewagetreatmentPollutantsRemovedComponentremovedPrimarytreatmentSecondarytreatmentBiologicaloxygendemand30%90%Suspendedsolids60%90%Nitrogencompounds20%50%Phosphoruscompounds10%30%Source:AmericanChemicalSocietySludgedisposalSludgeisanexcellentfertilizerinprinciple:richinorganicmaterialandnutrients.Sludgeoftencontainstoxicmetalspecies,whichrestrictstheapplicationofsludgetocropland.Sludgecanbealow-qualityfuelforgeneratingelectricity.Sludgecouldbeconvertedtomethanebyanaerobicbacteria,butthisoptionsufferspooreconomics.DisinfectionCommondisinfectants:Cholrine,chlorinedioxide,andozone.Disinfectantskillmicroorganismsbyoxidizingvitalmolecules(oftenwithunsaturatedcarbonbond)inthem.Cl2+H2O=HClO+H++Cl-HypochlorousacidActivedisinfectioncomponentProsandconsofvariousdisinfectantsCl2