給水排水專業(yè)英語課件

Unit16

ConventionalwastewaterTreatmentProcesses

傳統(tǒng)污水處理過程1Unit16

ConventionalwastewatConventionalwastewatertreatmentconsistsofpreliminaryprocesses(pumping,screening,andgritremoval),primarysettlingtoremoveheavysolidsandfloatablematerial,andsecondarybiologicalaerationtometabolizeandflocculatecolloidalanddissolvedorganics.傳統(tǒng)的廢水處理包括初步處理（提升，篩選和除砂），初沉去除重金屬固體和漂浮物質(zhì)，二級曝氣生物代謝和絮凝去除膠體和溶解的有機(jī)物。Wastesludgedrawnfromtheseunitoperationsisthickenedandprocessedforultimatedisposal(Fig.3~3).從這些單元操作產(chǎn)生的污泥，被濃縮以便最終處理（圖3?3）。2ConventionalwastewatertreatmPreliminaryTreatmentUnitsThefollowingpreliminaryprocessescanbeusedinmunicipalwastewatertreatment:coarsescreening(barracks),mediumscreening,comminution,flowmeasuring,pumping,gritremovalpre-aeration,flotation,flocculation,andchemicaltreatment.以下初步處理可以在市政污水處理中使用：粗篩（格柵），中篩選，粉碎，計(jì)量泵，抽，預(yù)曝氣除砂，氣浮，絮凝和化學(xué)處理。Thelatterthreearenotcommonindomesticwastewatertreatment.Thesepracticesaresometimesdictatedbytheindustrialpollutantsinthemunicipalwastewater.后三種在生活污水處理是不常見的。這些過程有時(shí)由城市污水所含的工業(yè)污染物決定。3PreliminaryTreatmentUnits3Flotationisusedtoremovefinesuspensions,greaseandfatsandisperformedeitherinaseparateunitorinapre-aerationtankalsousedforgritremoval.氣浮是用于去除細(xì)小懸浮物，油脂和脂肪，要么是在一個(gè)單獨(dú)的處理單元或在預(yù)曝氣池用于除砂。Ifadequatepretreatmentisprovidedbypetroleumindustriesandmeat-processingplants,flotationunitsarenotrequiredatamunicipalfacility.在石油工業(yè)和肉類加工廠處理中，如果有足夠的預(yù)處理，氣浮單元在市政設(shè)施是不需要的。Flocculationwithorwithoutchemicaladditionmaybepracticedonhigh-strengthmunicipalwastestoprovideincreasedprimaryremovalandpreventexcessiveloadsonthesecondarytreatmentprocessed.無論有沒有化學(xué)添加劑的絮凝過程，高濃度的市政污水必須經(jīng)過足夠的預(yù)處理，防止在二級處理中有過度負(fù)荷。Chlorinationofrawwastewaterissometimesusedforodorcontrolandtoimprovesettlingcharacteristicsofthewastes.原水的氯化有時(shí)用于氣味控制和提高廢物的穩(wěn)定特性。4FlotationisusedtoremovefiPrimaryTreatmentUnits

Primarytreatmentissedimentation.Incommonusage,thoughthetermincludesthepreliminarytreatmentprocesses.主要處理方法是沉淀。在常見的用法，雖然該術(shù)語包括前處理工藝。Sedimentationofraw

wastewaterispracticedinalllargemunicipalplantsandmustprecedetrickling(biological)filtration.在大型的市政污水廠中原水的沉淀和必須在滴濾池（生物處理）前。Completely

mixedactivated-sludgeprocessescanbeusedtotreatunsettledrawwastewater;however,thismethodisrestrictedtosmallmunicipalitiesbecauseofthecostsinvolvedinsludgedisposalandoperation.

完全混合式活性污泥法被用來處理不沉降的原水，然而，因?yàn)槲勰嗵幚碣M(fèi)用和操作，這個(gè)方法一般不在小的城市使用，5PrimaryTreatmentUnits

5SecondaryTreatmentUnitsPrimarysedimentationremoves30%~50%ofthesuspendedsolidsinrawmunicipalwastewater.初沉池能夠去除市政污水30％?50％的懸浮固體。Remainingorganicmatterisextractedinbiologicalsecondarytreatmenttotheallowableeffluentresidualusingactivated-sludgeprocesses,tricklingfilters,orbiologicaltowers.剩余的有機(jī)物在二級生物處理被吸附已達(dá)到出水的濃度標(biāo)準(zhǔn)，一般二級處理為活性污泥工藝，滴濾池或生物塔。Intheactivated-sludgemethodwastewaterisfedcontinuouslyintoanaeratedtank,where

microorganismssynthesizetheorganics.在活性污泥法，廢水被連續(xù)地送入曝氣池，在這里微生物合成有機(jī)物。6SecondaryTreatmentUnits6Theresulting

microbialfloc(activatedsludge)issettledfromtheaeratedmixedliquorunderquiescentconditionsinafinalclarifierandreturnedtotheaerationtank.產(chǎn)生的微生物絮體（活性污泥），在沉淀池中從曝氣混合液中分離出來，并返回到曝氣池。Theplanteffluentisclearsupernatantfromsecondarysettling.出廠水為二沉池后的上清液。Advantagesofliquidaerationarehigh-BODremovals,abilitytotreathigh-strengthwastewater,andadaptabilityforfutureuseinplantconversiontoadvancedtreatment.7Theresulting

microbialfloc(Ontheotherhand,ahighdegreeofoperationalcontrolisneeded,shockloadsmayupsetthestabilityofthebiologicalprocess,andsustainedhydraulicororganicoverloadingresultsinprocessfailure.另一方面，操作控制要求高，沖擊負(fù)荷會擾亂生物處理工藝的穩(wěn)定，持續(xù)的水力或者有機(jī)負(fù)荷會導(dǎo)致處理工藝的失敗。8Ontheotherhand,ahighdegrTricklingfiltersandrotatingbiologicalcontactorshavemediatosupportmicrobialfilms.滴濾池和生物轉(zhuǎn)盤通過媒介支撐生物膜。Theseslimegrowthsextractorganicsfromthewastewaterasittricklesoverthesurfaces.這些生物膜從流過濾料的廢水中吸取有機(jī)物。Oxygenissuppliedfromairmovingthroughvoidsinthemedia,Excessivebiologicalgrowthwashesoutandiscollectedinthesecondaryclarifier.氧氣從媒介中間的空隙補(bǔ)給。產(chǎn)生的過量生物膜被沖洗，在二沉池中收集。9TricklingfiltersandrotatingInnorthernclimatestwo-stagestone-mediatricklingfiltersareneededtoachieveefficienttreatment.在北方的氣候，兩階段的石頭濾料的滴濾池被采用以實(shí)現(xiàn)高效處理。Biologicaltowersmaybeeithersingle

ortwo-stagesystems.生物塔可以是一段或兩段系統(tǒng)。Advantagesoffiltrationareeaseofoperationandcapacitytoacceptshockloadsandoverloadingwithoutcausingcompletefailure.

過濾優(yōu)點(diǎn)在于易于操作而且能夠接受沖擊負(fù)荷和超負(fù)荷，而不會引起失敗。10Innorthernclimatestwo-stagSludgeDisposalPrimarysedimentationandsecondarybiologicalflocculationprocessesconcentratethewasteorganicsintoavolumeofsludgesignificantlylessthanthequantityofwastewatertreated.初沉污和二級生物絮凝過程濃縮廢物，形成的污泥體積遠(yuǎn)小于被處理污水的量。Butdisposaloftheaccumulatedwastesludgeisamajoreconomicfactorinwastewatertreatment.但是，收集起來的污泥的處置費(fèi)用是污水處理的主要因素。Theconstructioncostofasludgeprocessingfacilityisapproximatelyone-thirdthatofatreatmentplant.

污泥處理設(shè)施的建設(shè)費(fèi)大約占水廠費(fèi)用的1/3。11SludgeDisposal11Flowschemesforwithdrawal,holding,andthickeningrawwastesludgefromsedimentationtanksareillustratedinFig.3-4.圖3-4示意了沉淀池中污泥排出、存儲、濃縮流程圖。Thesettledsolidsfromclarificationoftricklingfiltereffluentarefrequentlyreturnedtotheplantheadforremovalwiththeprimarysludge(topdiagramFig.3-4).經(jīng)生物濾池出水后的沉淀物，返回水廠頭部，與初沉污泥一同被去除。Rawsettlingsmaybestoredintheprimarytankbottomuntilprocessedorpumpedintoaholdingtankforstorage.初沉池底部的沉淀物通過泵抽取到污泥池。12Flowschemesforwithdrawal,hThewithdrawnsludgemaybeconcentratedinathickener,usually

agravity-typeunit,priortoprocessing.排出的污泥在濃縮池中濃縮。InthebottomdiagramofFig.3-4,waste-activatedsludgeismixedwithprimaryresidueafterwithdrawal.在圖3-4的下面的示意圖中，剩余活性污泥與初沉污泥混合處理。Aholdingtankiscommonlyusedinthissystemarrangement,alongwithathickener.在濃縮池之前，存在一個(gè)污泥存儲池。Thewasteactivatedmaybethickenedseparatelyorthecombinedsludgethickenedpriortoprocessing.剩余活性污泥有可能被單獨(dú)濃縮，也有可能與其他污泥聯(lián)合濃縮。13ThewithdrawnsludgemaybecoCommonalternativesforprocessinganddisposalofrawsludgeareanaerobicdigestionandmechanicaldewateringbyvacuumorpressurefiltration.常見的方法處理和處置生污泥厭氧消化和機(jī)械脫水是由真空或壓力過濾。Centrifugationandwetcombustionarelessoftenemployed.離心和濕式燃燒更經(jīng)常使用。

Conventionalmethodsofdisposalincludeburialinlandfill,incineration,productionofsoilconditioner,andbargingtosea.常規(guī)方法處理包括埋葬在垃圾填埋、焚燒、生產(chǎn)的土壤改良劑，和駁運(yùn)到海洋。Forcoastalcitiesoceandumpingisoftenleastexpensive,whereasburialisregularlypracticediflandfillareaisavailable.對于沿海城市海洋傾倒往往是最便宜的，如果垃圾填埋區(qū)是可用的，填埋經(jīng)常采用。Incineration

althoughmorecostly,isfrequentlytheonlyfeasiblemethodofdisposalinurbanizedareas.焚燒，雖然更昂貴，通常是唯一可行的處置方法在城市化的地區(qū)。14CommonalternativesforprocesAllpossiblesludge-disposalprocessesforamunicipaltreatmentplantmustbegiven

carefulconsideration.對所有的污泥處置方式，污水廠必須仔細(xì)衡量。Themethodselectedshouldbethemosteconomicalprocess,ifitisbest,withdueregardtoenvironmentalconditions.Attentionmustbegiventosuchfactorsastruckingsludgethroughresidentialareas,futureuseoflandfillareas,groundwaterpollution,airpollution,otherpotentialpublichealthhazards,andesthetics.必須注意通過居住區(qū)的污泥運(yùn)輸?shù)纫蛩?，將來使用垃圾的地區(qū)，地下水污染、空氣污染、其他潛在的公共衛(wèi)生風(fēng)險(xiǎn)，和美學(xué)。15Allpossiblesludge-disposalpAdvancedwastewatertreatmentPhosphorusremovalispracticedinprocessingwastewaterthatdisch