专业英语(给排水与环境工程-李田)Unit-9

Unit9Sedimentation—p59新浪微博：南昌工程学院臾凉先森Newwordsandexpressionspotableadj.可饮用的，potablewaterClarificationn.澄清，净化clarifiern.澄清池，澄清器开.apparatusn.器械,设备,仪器prechlorinationn.预氯化inletn.进口turbulentadj.紊流的，湍流的Turbulencen.紊流，紊乱perimetern.周长圆周weirn.堰，溢流堰layoutn.规划,设计,(书刊等)编排,版面,(工厂的)布局图rectangularadj.矩形的，成直角的2新浪微博：南昌工程学院臾凉先森NewwordsandexpressionsInclinedtuben.斜管effluentadj.流出的n.流出物,出水Sphericaln.球形的球的depositn.沉淀物堆积物；储蓄存款Reinforcedconcreten.钢筋混凝土controversialn.争论的争议的Innovationn.改革创新inclinationadj.倾斜,弯曲,倾度,倾向,爱好hexagonaladj.六角形的六边形的backwashn.v.反洗反冲洗modulen.模数，模块，组件3新浪微博：南昌工程学院臾凉先森Sedimentationorclarificationistheremovalofparticulatematter,chemicalfloc,andprecipitatesfromsuspensionthroughgravitysettling.沉淀和澄清是从悬浮物中通过重力沉降去除颗粒物、化学絮凝产物和凝结沉淀物。Thismakeswaterclarificationavitallyimportantstepinthetreatmentofsurfacewatersforpotablesupplyandinmostcasesthemainfactorindeterminingtheoverallcostoftreatment.这使得水的澄清是饮用水供应中地表水处理的至关重要一步，在很多情况下，它也是决定全部水处理费用中主要的因素。Poordesignofthesedimentationbasinwillresultinreducedtreatmentefficiencythatmaysubsequentlyupsetotheroperations.糟糕的沉淀池设计将会导致降低处理效率，接下来这也许会影响到其它（水处理工艺）的运行。4新浪微博：南昌工程学院臾凉先森Surfacewatercontaininghighturbiditymayrequiresedimentationpriortochemicaltreatment.地表水（包含）在高浊度下就要求在化学处理工艺之前沉淀。Presedimentationbasinsareconstructedinexcavatedgroundoroutofsteelorconcrete.预沉淀池建在被挖坑的地下或用钢筋混凝土建造。Steelandconcretetanksareoftenequippedwithacontinuousmechanicalsludgeremovalapparatus.钢筋混凝土池通常装配有持续的机械除泥设施。5新浪微博：南昌工程学院臾凉先森Theminimumrecommendeddetentiontimeforpresedimentationis3h,althoughatmanytimesoftheyear,thismaynotbeadequatetoremovefinesuspensions.在预沉池，（被建议）规定的最短停留时间是3小时，尽管在一年的很多时候，这个时间可能不足够去去除细小悬浮物质。Chemicalfeedequipmentmaybeprovidedaheadofpresedimentationtoprovideprechlorinationorpartialcoagulationforperiodswhenwateristooturbidtoclarifybyplainsedimentation.当通过平流池水太浑浊而不能澄清时，化学药剂投加装置就需要设置在预沉池之前去预加氯或者添加部分的混凝剂。6新浪微博：南昌工程学院臾凉先森Settlingbasinsareusuallyprovidedforchemicalcoagulationorsoftening.沉淀池通常投加一些混凝剂和软化药剂。Thesebasinsmaybeconstructedofconcreteorsteelinawidevarietyofshapesandflowmechanisms.这些池子用钢筋混凝土建成各种各样的形状和流动机制。Tominimizetheeffectsofshort-circuitingandturbulentflow,careistakenintheeffectivehydraulicdesignofinletandoutletstructuresinalltanks.精心的考虑到所有池子进出口结构的水力设计，去最小化短流与紊流的影响。7新浪微博：南昌工程学院臾凉先森Inletstructuresareexpectedto:(1)uniformlydistributeflowoverthecrosssectionofthesettlingzone;(2)initiateparallelorradialflow;(3)minimizelarge-scaleturbulence;and(4)precludeexcessivevelocitiesnearthesludgezone.进口结构考虑部分包括以下几点：（1）一致地（均匀地）分配到沉淀区域的各个部分（2）发起平行或辐射状的流动（3）最小化产生大规模紊流（4）阻止靠近污泥的区域有过大的流速Flowthroughasedimentationbasinentersatthetopofthebasin.水流流经沉淀池到达池子的顶部Insomecircularbasins,theflowmayenteracentralflocculatingchamberofthebasin,effluentflowsverticallyoutoverperimeterweirs.在一些圆形的池子，水流将会流进池子中央的絮凝室，出流水流从周围的围堰垂直流出。8新浪微博：南昌工程学院臾凉先森Inrectangulartankswaterflowshorizontallytoanendweirfordischarge.在矩形的水池，水流水平地流向池子终点的出水堰。Anefficientlydesignedverticaltankismorestablethanahorizontalone.Theratingofaverticaltankasrelatedtothebulksettlingvelocityisusually3.3to9.8ft/h(1to3m/h).有效设计的竖流式沉淀池比平流池运行稳定。竖流式沉淀池的速率与较大絮凝体的沉速有关，通常为3.3到9.8英尺/小时（1到3米/小时）9新浪微博：南昌工程学院臾凉先森Recentdevelopmentshavebeenmadewiththeimplementationoftubesettlinginthedesignofhorizontal-flowsettlingtanks,whicharesaidtoovercomesomeofthepreviousdifficultiesandenablehigherratesofsedimentation.近期在平流沉淀池设计中，通过沉淀管的安装取得了一些进步，据说这些进步克服了先前的困难和提高了沉淀效率。Upflowsolidscontactclarifiers,andhorizontal-flowbasinsmayincreasetheirvolumetriccapacity50to150percentormorewiththeintroductionofinclinedtubesintotheirbasins.向上流的固体接触到澄清池和平流式沉淀池会增加50%—150%的处理能力，或者通过采用斜管沉淀池可以增加更多的处理能力。Similarorimprovedeffluentqualityisobservedinthesemodifiedprocesses.类似的或改善的出水水质在这些改进的工艺中被研究观察。10新浪微博：南昌工程学院臾凉先森Effluentqualityforanysedimentationprocessisdependentuponpreviouswaterquality,coagulantsadded,mixing,flocculation,andfiltration.一些沉淀工艺的出流水质取决于进水水质、混凝剂的投加、混合、絮凝和过滤。Withtheexceptionofpresedimentation,sedimentationprocessesareusuallyprecededbycoagulationandfollowedbyfiltration.除了预沉淀工艺，沉淀工艺通常先于混凝后于过滤。Therefore,typicalremovalsofregulatedcontaminantsbysedimentationandfiltrationarereportedaccordingtocoagulantsusedinconjunctionwiththeseprocessesforremovalofaspecificcontaminant.因此，通过沉淀和过滤工艺来去除典型污染物的去除率，是按照使用在这些工艺中去除特定污染物的混凝剂来确定的。11新浪微博：南昌工程学院臾凉先森Basically,thetheoryofsedimentationisthetheoryoftheeffectofgravityonparticlessuspendedinaliquidoflesserdensity.从根本上说，沉淀理论是颗粒物悬浮在比其密度更低的液体中，利用重力的作用沉淀。Undertheinfluenceofgravity,anyparticlehavingadensitygreaterthan1.0willsettleinwateratanacceleratingvelocityuntiltheresistanceoftheliquidequalstheeffectiveweightoftheparticle.在重力的影响下，任何密度大于水的颗粒物将会以加速度在水中沉降，直到液体对颗粒物的阻力等于其自身重力时，（加速度才变为零）。Thereafter,thesettlingvelocitywillbeessentiallyconstantandwilldependuponthesize,shape,anddensityoftheparticle,aswellasthedensityandviscosityofthewater.此后，颗粒物的沉速本质上将不会改变和其沉速取决于它的大小、形状和密度，同样取决于水的密度和粘滞性。12新浪微博：南昌工程学院臾凉先森Formosttheoreticalandpracticalcomputationsofsettlingvelocitiesinsedimentationbasins,theshapeoftheparticlesisassumedtobespherical.