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1、Unit7SelectionofWater TreatmentProcesses05.12.2Profession-relatedEnglishWatershedmanagementshouldbeconsideredpartoftheoperationofawater-supplysystem,which（指代前面所说的事情）isveryimportanttoprotectrawwaterquality.流域管理应当被看作是供水系统运行的一部分，这对于保护原水质量十分重要。Behindanintakestructu
2、re,therecomeswatertreatmentprocess（倒装结构）.在取水工程后面，是水处理过程。Profession-relatedEnglishProfession-relatedEnglishCurrentpretreatmentprocessesinmunicipalwatertreatmentarescreening,presedimentationordesilting,chemicaladdition,andaeration.目前市政水处理中的预处理工艺有筛分，预沉淀或沉砂，化学混凝和曝气
3、。Presedimentationisregularlyusedtoremovesuspendedmatterfromriverwater.预沉淀习惯上用于从河水中去除悬浮物。Chemicaltreatment,inadvanceof（在……前面）in-plantcoagulation,ismostfrequentlyappliedtoimprovepresedimentation,topretreathard-toremovesubstances,suchastasteandodorcompoundsandcolo
4、r,andtoreducehighbacterialconcentrations.在混凝处理前面，化学处理最频繁地被用作改善预沉淀，或对难去除的物质进行预处理，例如嗅味物质、色度和减小高的细菌浓度。Profession-relatedEnglishConventionalchemicalsusedwithpresedimentrationarethepolyelectrolytesandalum.用来进行预沉淀处理的传统的化学物质是高分子聚合物和铝。Profession-relatedEnglishAerationi
5、scustomarilythefirststepintreatmentfortheremovalofironandmanganesefromwellwatersandastandardwaytoseparatedissolvedgasessuchashydrogensulfideandcarbondioxide.对于从井水中去除铁和锰，习惯上曝气作为处理的第一步。同时，曝气也是分离诸如硫化氢和二氧化碳等溶解性气体的标准方法。Profession-relatedEnglishTreatmentprocessesused
6、inwaterplantsdependontheraw-watersourceandqualityoffinishedwaterdesired.水厂使用的处理工艺依赖于原水水源和对处理水的期望。Thespecificchemicalsselectedfortreatmentarebasedontheireffectivenesstoperformthedesiredreactionandcost.处理中所选用的药剂是以它们的处理效果和费用为基础的。Profession-relatedEnglishForexample
7、,activatedcarbon,chlorine,chlorinedioxide,andpotassiumpermanganateareallusedfortasteandodorcontrol.例如，活性碳、氯、二氧化氯和高锰酸钾，都被用来控制嗅味。Profession-relatedEnglishExcesschlorination,althoughleastexpensive,cancreateundesiredtrihalomethanes;activatedcarbonisthemosteffective
8、chemical.过量使用氯，尽管费用上增加很少，但产生不期望的三氯代甲烷；活性炭是最有效的化学剂。Profession-relatedEnglishInsurface-watertreatmentplantsequipmentforfeedingtwoorthreetaste-andodor-removalchemicalsisusually
