给水排水专业英语课件16

1Unit16ConventionalwastewaterTreatmentProcesses传统污水处理过程2Conventionalwastewatertreatmentconsistsofpreliminaryprocesses(pumping,screening,andgritremoval),primarysettlingtoremoveheavysolidsandfloatablematerial,andsecondarybiologicalaerationtometabolizeandflocculatecolloidalanddissolvedorganics.传统的废水处理包括初步处理（提升，筛选和除砂），初沉去除重金属固体和漂浮物质，二级曝气生物代谢和絮凝去除胶体和溶解的有机物。Wastesludgedrawnfromtheseunitoperationsisthickenedandprocessedforultimatedisposal(Fig.3~3).从这些单元操作产生的污泥，被浓缩以便最终处理（图3〜3）。3PreliminaryTreatmentUnitsThefollowingpreliminaryprocessescanbeusedinmunicipalwastewatertreatment:coarsescreening(barracks),mediumscreening,comminution,flowmeasuring,pumping,gritremovalpre-aeration,flotation,flocculation,andchemicaltreatment.以下初步处理可以在市政污水处理中使用：粗筛（格栅），中筛选，粉碎，计量泵，抽，预曝气除砂，气浮，絮凝和化学处理。Thelatterthreearenotcommonindomesticwastewatertreatment.Thesepracticesaresometimesdictatedbytheindustrialpollutantsinthemunicipalwastewater.后三种在生活污水处理是不常见的。这些过程有时由城市污水所含的工业污染物决定。4Flotationisusedtoremovefinesuspensions,greaseandfatsandisperformedeitherinaseparateunitorinapre-aerationtankalsousedforgritremoval.气浮是用于去除细小悬浮物，油脂和脂肪，要么是在一个单独的处理单元或在预曝气池用于除砂。Ifadequatepretreatmentisprovidedbypetroleumindustriesandmeat-processingplants,flotationunitsarenotrequiredatamunicipalfacility.在石油工业和肉类加工厂处理中，如果有足够的预处理，气浮单元在市政设施是不需要的。Flocculationwithorwithoutchemicaladditionmaybepracticedonhigh-strengthmunicipalwastestoprovideincreasedprimaryremovalandpreventexcessiveloadsonthesecondarytreatmentprocessed.无论有没有化学添加剂的絮凝过程，高浓度的市政污水必须经过足够的预处理，防止在二级处理中有过度负荷。Chlorinationofrawwastewaterissometimesusedforodorcontrolandtoimprovesettlingcharacteristicsofthewastes.原水的氯化有时用于气味控制和提高废物的稳定特性。5PrimaryTreatmentUnitsPrimarytreatmentissedimentation.Incommonusage,thoughthetermincludesthepreliminarytreatmentprocesses.主要处理方法是沉淀。在常见的用法，虽然该术语包括前处理工艺。Sedimentationofrawwastewaterispracticedinalllargemunicipalplantsandmustprecedetrickling(biological)filtration.在大型的市政污水厂中原水的沉淀和必须在滴滤池（生物处理）前。Completelymixedactivated-sludgeprocessescanbeusedtotreatunsettledrawwastewater;however,thismethodisrestrictedtosmallmunicipalitiesbecauseofthecostsinvolvedinsludgedisposalandoperation.完全混合式活性污泥法被用来处理不沉降的原水，然而，因为污泥处理费用和操作，这个方法一般不在小的城市使用，6SecondaryTreatmentUnitsPrimarysedimentationremoves30%~50%ofthesuspendedsolidsinrawmunicipalwastewater.初沉池能够去除市政污水30％〜50％的悬浮固体。Remainingorganicmatterisextractedinbiologicalsecondarytreatmenttotheallowableeffluentresidualusingactivated-sludgeprocesses,tricklingfilters,orbiologicaltowers.剩余的有机物在二级生物处理被吸附已达到出水的浓度标准，一般二级处理为活性污泥工艺，滴滤池或生物塔。Intheactivated-sludgemethodwastewaterisfedcontinuouslyintoanaeratedtank,wheremicroorganismssynthesizetheorganics.在活性污泥法，废水被连续地送入曝气池，在这里微生物合成有机物。7Theresultingmicrobialfloc(activatedsludge)issettledfromtheaeratedmixedliquorunderquiescentconditionsinafinalclarifierandreturnedtotheaerationtank.产生的微生物絮体（活性污泥），在沉淀池中从曝气混合液中分离出来，并返回到曝气池。Theplanteffluentisclearsupernatantfromsecondarysettling.出厂水为二沉池后的上清液。Advantagesofliquidaerationarehigh-BODremovals,abilitytotreathigh-strengthwastewater,andadaptabilityforfutureuseinplantconversiontoadvancedtreatment.8Ontheotherhand,ahighdegreeofoperationalcontrolisneeded,shockloadsmayupsetthestabilityofthebiologicalprocess,andsustainedhydraulicororganicoverloadingresultsinprocessfailure.另一方面，操作控制要求高，冲击负荷会扰乱生物处理工艺的稳定，持续的水力或者有机负荷会导致处理工艺的失败。9Tricklingfiltersandrotatingbiologicalcontactorshavemediatosupportmicrobialfilms.滴滤池和生物转盘通过媒介支撑生物膜。Theseslimegrowthsextractorganicsfromthewastewaterasittricklesoverthesurfaces.这些生物膜从流过滤料的废水中吸取有机物。Oxygenissuppliedfromairmovingthroughvoidsinthemedia,Excessivebiologicalgrowthwashesoutandiscollectedinthesecondaryclarifier.氧气从媒介中间的空隙补给。产生的过量生物膜被冲洗，在二沉池中收集。10Innorthernclimatestwo-stagestone-mediatricklingfiltersareneededtoachieveefficienttreatment.在北方的气候，两阶段的石头滤料的滴滤池被采用以实现高效处理。Biologicaltowersmaybeeithersingleortwo-stagesystems.生物塔可以是一段或两段系统。Advantagesoffiltrationareeaseofoperationandcapacitytoacceptshockloadsandoverloadingwithoutcausingcompletefailure.过滤优点在于易于操作而且能够接受冲击负荷和超负荷，而不会引起失败。11SludgeDisposalPrimarysedimentationandsecondarybiologicalflocculationprocessesconcentratethewasteorganicsintoavolumeofsludgesignificantlylessthanthequantityofwastewatertreated.初沉污和二级生物絮凝过程浓缩废物，形成的污泥体积远小于被处理污水的量。Butdisposaloftheaccumulatedwastesludgeisamajoreconomicfactorinwastewatertreatment.但是，收集起来的污泥的处置费用是污水处理的主要因素。Theconstructioncostofasludgeprocessingfacilityisapproximatelyone-thirdthatofatreatmentplant.污泥处理设施的建设费大约占水厂费用的1/3。12Flowschemesforwithdrawal,holding,andthickeningrawwastesludgefromsedimentationtanksareillustratedinFig.3-4.图3-4示意了沉淀池中污泥排出、存储、浓缩流程图。Thesettledsolidsfromclarificationoftricklingfiltereffluentarefrequentlyreturnedtotheplantheadforremovalwiththeprimarysludge(topdiagramFig.3-4).经生物滤池出水后的沉淀物，返回水厂头部，与初沉污泥一同被去除。Rawsettlingsmaybestoredintheprimarytankbottomuntilprocessedorpumpedintoaholdingtankforstorage.初沉池底部的沉淀物通过泵抽取到污泥池。13Thewithdrawnsludgemaybeconcentratedinathickener,usuallyagravity-typeunit,priortoprocessing.排出的污泥在浓缩池中浓缩。Intheb