污水处理技术外文翻译.docx

污水处理技术外文翻译.docx

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污水处理技术外文翻译

本科毕业设计

外文文献及译文

文献、资料题目：

StudyonDisinfectionand

Anti–microbialTechnologiesforDrinkingWater

文献、资料来源：

期刊

文献、资料发表（出版）日期：

2001.1.9

院（部）：

专业：

给水排水工程

班级：

姓名：

学号：

指导教师：

翻译日期：

2010.3.30

外文文献：

StudyonDisinfectionandAnti–microbialTechnologiesforDrinkingWater

ZHUKun,FUXiaoYong

（Dept.ofEnvironmentalEngineering,LANZhouRailwayUniversity,LANZhou730070,China）

Abstract:

Disinfectionby-productsproducedbythereactionbetweenchlorineanddissolvedorganiccompoundsandotherchemicalsareconsideredasaworryingprobleminthedrinkingwatertreatmentprocesssinceaseriesofmutageniccarcinogensubstancesareformedincludingtrihalomethanes（THMs）.Amongthetesteddisinfectants（chlorine,ozone,chlorinedioxide,potassiumpermanganate,chloraminesandhydrogenperoxideetc.）,chlorinedioxidehasprovedtobethemostfeasibleandeffectiveoxidantfordrinkingwatertreatmentandremovalofpathogensduetoitsoxidationefficiency,lowcostandsimplewayofutilization.Aseriesofexperimentsindicatethatchlorinedioxidecansignificantlyrestrainproductionoftrihalomethanes（THMs）andcontrolbacteriagrowthparticularlyforCryptosporidiumoocysts.Theexperimentsverifiedthatbothozoneandchlorinedioxideareabsolutelyvitaltoensurethatanymicroorganismsarisingfromfecalcontaminationofwaterstoragearedestroyed.Thepaperdiscussesoxidationcapacityofchlorinedioxide,especiallyforremovingpetroleumcompounds,whichisaffectedbyreactiontime,gasinjectionway,andpHoftreatedwater.

Keywords:

disinfection;oxidants;watertreatment;pathogens;chlorinedioxide

CLCnumber:

X523Documentcode:

A

1　Introduction

ChemicalandfiltrationprocessesaretwomainmethodsusedinChinafortreatingdrinkingwatermeanwhileUVradiationhasbeenusedsuccessfullyforwatertreatmentwithrelativelylowflowrate.Ontheindividualfamilylevel,usuallychemicaltreatmentisafeasiblealternative.Thefollowingguidelinesexistfortheselectionofsuitabledisinfectants:

thereactionmustbestrongenoughtoextinctbacteriaandcontrolgrowthofmicro-organisms,removalofcontaminantsshouldbedonebydecomposition,evaporationorprecipitationetc,toeliminateordecreasethetoxicity,oxidantsorreactionby-productsshouldnotbeharmfultohumanhealth,andthepurificationprocessesshouldbepracticalandeconomical.Theobjectiveofthispaperistoevaluateanddiscussavailabledisinfectantsfordrinkingwatertreatment.Thedifferentdisinfectantsarecomparedregardingpurificationefficienciesandapplicationapproaches.

2　ComparisonofDisinfectants

Disinfectants,suchaschlorine,chloramines,sodiumhypochlorous,chlorinedioxideandozoneetc.,wereprimarilyconsideredindrinkingwatertreatment.Theoxidationcapacitiesoftheseagentsmayberankedasfollowsinorderofdecreasedefficiency[1]:

O3>ClO2>HOCl>OCl->NHCl2>NH2Cl

ReferringtoFiessinger′s[2]suggestion,thepropertiesofthesedisinfectantsarecomparedinTab.1.Chlorineisshowntobeanexcellentdisinfectanttopreventwaterbornediseasessuchastyphoidfeveroverlongperiods.Chlorinereactsnotonlywithinoxidation,butalsobyelectrophilicsubstitutiontoproduceavarietyofchlorinatedorganicby-products,particularlytrihalomethanes（THMs）andothermutagens.HereTHMsmainlyrefertochloroform,bromoform,dibromochloromathaneandbromodichloromathaneetc.Sincethe1970`s,theusageofCl2indrinkingwaterdisinfectionhasbeenquestionedwithozonebeingsubstitutedasthepreferreddisinfectantinthewatersupplyplants.But,ozonecouldnotbeintroducedtotheruralfarmercommunityduetoitshighcostsandshorthalf-life（15～20min.）.Aswithotherdisinfectants,ozonationalsoleadstoformationoforganicby-productssuchasaldehyde,ketones,andcarboxylicacids,andalsomutagenicitymaybeinducedifbromicanionexists.

Tab.1Comparisonofvariousoxidants

ComparisonCl2ClO2O3KMnO4NH2ClH2O2

THMformation+++-----

Disinfectioneffects++++++++-+-+

Enhancedbiodegradability

++++++-+

Tasteremoval-++++-+

Ironandmanganese++++++++-+

Ammonia+++-----

Formationofmutagensortoxicsubstances

+++-+-+-+-+-

　　-noeffect;　+littleeffect;　++effect;　+++largesteffect

Manystudieshavepointedoutthatdisinfectionisabsolutelyvitaltoensurethatanymicroorganismsarisingfromfecalcontaminationofwaterstoragearedestroyed.Theselectionoftheavailabledisinfectantsmustconcerntoreduceriskfrommicrobialcontaminationofdrinkingwaterandthepotentialincreaseinriskfromchemicalcontaminationthatresultfromusinganyofthedisinfectants.Thebiocidalefficiencyofcommonlyuseddisinfectants-ozone,chlorinedioxide,chlorineandchloraminesarerankedalmostwiththesameorderastheoxidizingcapacity,butthestabilityofthosearefollowingtheorderas[3]:

Chloramines>Chlorinedioxide>Chlorine>Ozone

3　Purificationoforganicpollutantsbychlorinedioxide

AccordingtoWHOguidelinefordrinkingwaterquality,muchconsiderationshouldbepaidtobenzenehomologouscompounds;therefore,thestudyonpurificationeffectsofchlorinedioxideisfocusedonpetrochemicalpollutants.Aseriesofexperimentswerecarriedouttosimulatetheoxidationprocessesofcontaminatedwater.Thepollutedsolutionswerepreparedinadarkbarrel（10Lcapacity）ofsevenkindsofbenzenehomologouscompounds-Benzene,toluene,ethylbenzene,p-phenylmethane,o-phenylmethane,m-phenylmethaneandstyrene.Samplesweretakentodeterminetheinitialconcentrationofthecompoundspriortothetests.StandardchlorinedioxidesolutionwasproducedfromsodiumchloritereactedwithHClsolutionof10%[4].TheGR-16AGas-chromatographwithFIDdetectorShenyangLZ-2000wasusedformeasurementofCl2,ClO2,ClO-2andClO-3[5].OilconcentrationsweredeterminedwithanUV-120-20spectrophotometer（Shimadzu）followingtheproceduredescribedbyAPHA[4].OrganiccompoundsinthewatersamplesweremeasuredwithaGC-MS（QP-1000A）.ClO2andO3werestandardizedbyiodimetrictitrationatpH7.

Forthepurposeofchemicaldisinfectionfordrinkingwater,chlorinewasinstantaneouslyignoredduetotheformationofTHMsandothermutagenicsubstances.Theresultsindicatedthatpotassiumpermanganateandhydrogenperoxidedidnothaveenoughoxidationcapabilitytodecomposepetroleumcontaminantsachievingonly46%,and5.7%decompositionofstyrene,respectively.Ozonecouldnotbeselectedduetoitshighcost,complexoperationandshorthalf-lifealthoughitisanexcellentoxidantforwatertreatment.Chlorinedioxidewasthenextmostsuccessfulalternativefordisinfection.Thebenefitsinclude-effectiveoxidationcapacity,algicidaleffectandnegligibleformationofhalogenatedby-products.Basedoneconomicandoperationalrequirement,themixinggasmethodiseasilyused.TheresultsobtainedsuggestthatdisinfectionofdrinkingwaterwithozoneandorchlorinedioxideseemstobeasuitablealternativestotheuseofNaClOforcontrollingtheformationofnon-volatilemutagens[6].

Inthelaboratoryexperiments,theoxidantsozone,chlorinedioxide,potassiumpermanganateandthemixinggas（mainlycontainedClO2andacertainamountofCl2,O3andH2O2）weretestedforremovalofthepetroleumcompounds,andresultsareshowninTab.2.

Tab.2Comparisonofoxidationcapacityforthevariousoxidants

OrganicCompoundsInitialconc.O3ClO2H2O2MixingGasKMnO4

/mg·L–1

Oil11.3467.245.8061.80

Benzene3.6178.371.4082.30

Toluene5.2391.883.0095.20

Ethylbenzene8.3795.191.1094.50

p–phenylmethane7.8695.890.50100

o-phenylmethane8.3695.990.301000

m–phenylmethane9.2995.487.301000

Styrene9.3696.284.75.710046.1

Astudywasconductedtoelucidatethedecaypathwayofmonochloramineinthepresenceandabsenceofnaturalorganicmatter（NOM）[7].Itwasfoundthatnaturalorganicmatteractedprimarilyasareductantratherthancatalyst.Thisconclusionwasverifiedusingaredoxbalance,andmuchofoxidizingcapacityofmonochloraminegoestowardsNOMoxidation.Cleaningagentsanddisinfectantsfromhousekeeping,hospitals,kitchensaresourcesofabsorbablehalogenatedorganiccompounds（AOX）inmunicipalwastewater.TheamountofAOXgeneratedstronglydependsonthenatureandconcentrationsofdissolvedandsolidorganiccompounds,theconcentrationofactivesubstances,temperature,pHandreactiontime[8]Whenthemixinggasesreactwithwatermoleculesandorganicmicro-pollutants,hypochlorousacidisformedbychlorine,chloriteandchlorateionsareproducedfromchlorinedioxideinaseriesofredoxreactions.Theprincipalreactionsaresummarizedasfollows:

ClO2+organic→ClO-²+oxidizedorganic

（1）

2ClO-²+Cl2=2ClO2+2Cl-

（2）

2ClO-²+HOCl=2ClO2+2Cl-+OH-（3）

2ClO2+HOCl+H2O=2ClO-³+HCl+2H+（4）

TherateofchlorateyieldcanbedescribedbyEquation（5）:

d[ClO3]/dt=2k[ClO2][HOCl]（5）

inwhichk=1.28M/minat25℃[9].

Thestoichiometryoftheundesirablereactionsthatformchlorateinlowconcentrationofchloriteorpresentsofexcesschlorineisgivenas:

ClO-²+Cl2+H2O=ClO-³+2Cl-+2H+（6）

ClO-²+HOCl=ClO-³+Cl-+H+（7）

Atalkalineconditions:

ClO-²+HOCl+OH-=ClO-³+Cl-+H2O（8）

Typically,chlorinedioxideisusedindrinkingwatertreatmentandtheconcentrationsarerangingfrom0.1to2.0mg/L[10].However,therelevantby-productsofchlorinedioxidetreatme