给水排水专业英语课件(李田)11

1Unit11Disinfection2Newwordsandexpressionspathogenicadj.致病的病原的ozonen.臭氧potassiumn.钾permanganaten.高锰酸盐高锰酸injectorn.水射器注射器chlorinatorn.加氯机feedwatern.供水补给水bacteriologicaladj.细菌学的,细菌学上的breakpointchlorinationn.折点加氯/氯化postchlorinationn.后氯化3hypochloriten.次氯酸盐hypo-“在...之下,亚,次,次于,不足,从属于”hypochlorousadj.次氯酸的hypochlorousacidn.次氯酸hydrochloricadj.氯化氢的盐酸的dissociatev.分离,电离ionizevt.使离子化vi.电离equilibrian.均衡,平衡equilibrium的复数形式ammoniumn.铵ammonian.氨,氨水chloraminen.氯胺monochloraminen.一氯胺di-tri-4trichloriden.三氯化物sterilen.灭活杀菌adj.消过毒的无菌的sufficevi.足够有能力vt.使满足Fiftydollarswillsufficeme.chloriten.亚氯酸盐chloraten.氯酸盐Precursorn.前驱前驱物diaphragmn.横隔膜光圈振动膜ozonationn.臭氧化ozonator臭氧发生器dessicantn.干燥剂dessicatev.干燥ceramicn.陶瓷制品adj.陶器的cyaniden.氰化物5Thedestructionofpathogenicbacteriainwaterhasalwaysbeenofprimaryconcerninthetreatmentofpotablewater.Severalmethodsareavailablefordisinfection,includingchlorine,chlorinedioxide,ozone,andpotassiumpermanganate.ChlorinationisthetraditionaldisinfectiontechniquepracticedintheUnitedStates.Chlorineisshipped,inliquidform,inpressurizedsteelcylindersranginginsizefrom100lb.to1ton.6Chlorinegasisdrawnfromthepressurizedcylinderthroughasolutionfeederwhichcontrolstherateofapplication.Theinjector,inasolutionfeedchlorinator,dissolvesthegasintothefeedwater.Theconcentratedsolutionisthenappliedtotheprocesswater.Bothsurfaceandgroundwaterwatersuppliesrequireachlorineresidualtoensuregoodbacteriologicalqualityinthedistributionsystem.7Breakpointchlorination,priortocoagulationofasurfacewater,maybepracticedatcertaintimesoftheyearfortasteandodorcontrolinadditiontodisinfection.除了消毒（加氯）外，在地表水的混凝处理之前进行折点加氯，可能用于一年中的某些时候的臭味控制。Intermediateorpostchlorinationmayalsoberequiredtomaintaindisinfectionthroughouttheplantanddistributionsystem.为保持整个水厂和配水系统的消毒效果,需要中间氯化或者后氯化处理.8ChemistryofChlorinationChlorineisusedintheformoffreechlorineorashypochlorites.Ineitherformitactsasapotentoxidizingagentandoftendissipatesitselfinsidereactionssorapidlythatlittledisinfectionisaccomplisheduntilamountsinexcessofthechlorinedemandhavebeenadded.氯以自由氯或者次氯酸盐的形式应用。无论何种形式，作为强氧化剂——氯是如此之快的消耗于副反应上，以致于直到投加量超过需氯量时，才能起到消毒作用。9ReactionswithWaterChlorinecombineswithwatertoformhypochlorousandhydrochloricacids.Cl2+H20=HOCl+H++Cl-(2-1)Theformer,beingaweakacid,isverypoorlydissociatedatpHlevelsbelow6.IndilutesolutionandatpHlevelsabove4,theequilibriumshownaboveisdisplacedgreatlytotherightandverylittleCl2existsassuchinsolution.前者作为一种弱酸，在pH小于6的情况下难溶于水。在稀溶液中pH大于4的情况下，上述平衡大幅度向右移动，导致很少氯气存在于溶液中。10Hypochloritesareusedlargelyintheformofmodern-dayhigh-testcalciumhypochlorites.Whensuchcompoundsaredissolvedinwater,theyionizetoyieldhypochloriteion.Ca(OCl)2+H2O=Ca2++H20+2OC1-(2-2)Thision,ofcourse,establishedanequilibriumwithhydrogenionsinaccordancewiththeequationOC1-+H+=HOCl(2-3)TheamountsofOC1-ionandHOClinthesolutiondependuponthepH.高效次氯酸钙建立平衡11Naturalwatersalwayscontainsomechlorideions,andsothehypochlorousacidandchlorideandhydrogenionspresentinthewaterexistinequilibriumwithfreechlorine,asshowninEq.(2-1).天然水中总是含有一些氯离子，因此存在于水中的次氯酸、氯离子、氢离子和自由氯之间存在着如式（2-1）所示的平衡关系Thus,itcanbeconcludedthatthesameequilibriaareestablishedinwaterregardlessofwhetherchlorineorhypochloritesareadded.因此，可以得到结论，不管氯或次氯酸根添加与否，在水中都建立了相同的平衡。12ThesignificantdifferencewouldbeinpHeffectsandtheinfluenceofchlorineorhypochloritesontherelativeamountsofOCl-andHOClatequilibrium.ChlorinetendstodecreasethepH,whereashypochloritestendtoincreasethepH.13ReactionswithAmmoniaAmmoniumionsexistinequilibriumwithammoniaandhydrogenions.Theammoniareactswithchlorineorhypochlorousacidtoformmonochloramines,dichloramines,andtrichloramines,dependingupontherelativeamountsofeachandtosomeextentuponthepH,asfollows:NH3+HOCl=NH2C1+H20(monochloramine)(2-4)NH2CI+HOCI=NHC12+H20(dichloramine)(2-5)NHCI2+HOCl=NCl3+H20(trichloramineornitrogentrichloride)(2-6)Themono-anddichloramineshavesignificantdisinfectingpowerandare,therefore,ofinterestinthemeasurementofchlorineresiduals.14ChlorineResidualsDisinfectionisaprocessdesignedtokillharmfulorganisms,anditdoesnotordinarilyproduceasterilewater.消毒是一个设计用于杀死有害生物体的过程，而通常不是用于生产无菌水的Thesegeneralizationsholdfordisinfectionwithchlorinealso.Twofactorsareextremelyimportantindisinfection:timeofcontactandconcentrationofthedisinfectingagent.15Whereotherfactorsareconstant,thedisinfectingactionmayberepresentedbyKill=C•tTheimportantpointisthatwithlongcontacttimesalowconcentrationofdisinfectantsuffices,whereasshortcontacttimesrequirehighconcentrationtoaccomplishequivalentkills.最重要的一点是，接触时间长，低浓度的消毒剂即可满足要求，然而接触时间短，就要求高的浓度来完成相当的消毒效果。16Furthermore,researchhasshownthatagreaterconcentrationofchloraminesthanofhypochlorousacidisrequiredtoaccomplishagivenkillinaspecifiedtime.Forthesereasonsitisimportanttoknowboththeconcentrationandthekindofresidualchlorineacting.Fromtheconsiderationsmentionedabove,ithasbecomecommonpracticetorefertochlorine,hypochlorousacid,andhypochloriteionasfreechlorineresiduals,andthechloraminesarecalledcombinedchlorineresiduals.17Theactionofexcesschlorineonwaterscont