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：

期干刊

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;chlorinedioxideCLCnumber:

X523Documentcode:

A

1Introduction

ChemicalandfiltrationprocessesaretwomainmethodsusedinChinafortreatingdrinkingwatermeanwhileUVradiationhasbeenusedsuccessfullyforwatertreatmentwithrelativelylowflowrate.Ontheindividualfamilylevel,usuallychemicaltreatmentisafeasiblealternative.Thefollowingguidelinesexistfortheselectionofsuitabledisinfectants:

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

2ComparisonofDisinfectants

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

03>CI02>HOCI>OCI->NHCI2>NH2CI

ReferringtoFiessinger's[2]suggestiopettiespofthesedisinfectantsarecomparedinTab.1.Chlorineisshowntobeanexcellentdisinfectanttopreventwaterbornediseasessuchastyphoidfeveroverlongperiods.Chlorinereactsnotonlywithinoxidation,butalsobyelectrophilicsubstitutiontoproduceavarietyofchlorinatedorganicby-products,particularlytrihalomethanes（THMs）andothermutagens.HereTHMsmainlyrefertochloroform,bromoform,dibromochloromathaneandbromodichloromathaneetc.Sineethe1970's,theusageofCl2indrinkingwaterdisinfectionhasbeenquestionedwithozonebeingsubstitutedasthepreferreddisinfectantinthewatersupplyplants.But,ozonecouldnotbeintroducedtotheruralfarmercommunityduetoitshighcostsandshorthalf-life（15〜20min.）.Aswithotherdisinfectants,ozonationalsoleadstoformationoforganicby-productssuchasaldehyde,ketones,andcarboxylicacids,andalsomutagenicitymaybeinducedifbromicanionexists.

Tab.1Comparisonofvariousoxidants

ComparisonCl2

H2O2

ClO203

KMnO4

NH2CI

THMformation+++-----

Disinfectioneffects+

+++++++-

+-

+

Enhancedbiodegradability

+++++

+-

+

Tasteremoval-

++++

-

+

Ironandmanganese+

+++++++

-

+

Ammonia+++

Formationofmutagensortoxicsubstances

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

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

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

Chloramines>Chlorinedioxide>Chlorine>Ozone

3Purificationoforganicpollutantsbychlorinedioxide

AccordingtoWHOguidelinefordrinkingwaterquality,muchconsiderationshouldbepaidtobenzenehomologouscompounds;therefore,thestudyonpurificationeffectsofchlorinedioxideisfocusedonpetrochemicalpollutants.Aseriesofexperimentswerecarriedouttosimulatetheoxidationprocessesofcontaminatedwater.Thepollutedsolutionswerepreparedinadarkbarrel（10Lcapacity）ofsevenkindsofbenzenehomologouscompounds-Benzene,toluene,ethylbenzene,p-phenylmethane,o-phenylmethane,m-phenylmethaneandstyrene.Samplesweretakentodeterminetheinitialconcentrationofthecompoundspriortothetests.StandardchlorinedioxidesolutionwasproducedfromsodiumchloritereactedwithHClsolutionof10%[4].TheGR-16AGas-chromatographwithFIDdetectorShenyangLZ-2000wasusedformeasurementofC2,CIO2,ClO-2andCIO-3[5].OilconcentrationsweredeterminedwithanUV-120-20spectrophotometer（Shimadzu）followingtheproceduredescribedbyAPHA[4].OrganiccompoundsinthewatersamplesweremeasuredwithaGC-MS（QP-1000A）.CIQandO3werestandardizedbyiodimetrictitrationatpH7.

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

Inthelaboratoryexperiments,theoxidantsozone,chlorinedioxide,potassiumpermanganateandthemixinggas（mainlycontainedCIO2andacertainamountofCl2,03andH2O2）weretestedforremovalofthepetroleumcompounds,andresultsareshowninTab.2.

Tab.2Comparisonofoxidationcapacityforthevariousoxidants

OrganicCompounds

Initialcone.

/mgL-1

O3

ClO2

H2O2

MixingGas

KMnO4

Oil

11.34

67.2

45.8

0

61.8

0

Benzene

3.61

78.3

71.4

0

82.3

0

Toluene

5.23

91.8

83.0

0

95.2

0

Ethylbenzene

8.37

95.1

91.1

0

94.5

0

p-phenylmethane

7.86

95.8

90.5

0

100

o-phenylmethane

8.36

95.9

90.3

0

100

0

m-phenylmethane

9.29

95.4

87.3

0

100

0

Styrene

9.36

96.2

84.7

5.7

100

46.1

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

CIO2+organicfClO+oxidizedorganic

（1）

2ClO-2+Cl2=2CIO2+2Cl-

（2）

2ClO-2+HOCl=2ClO2+2Cl-+OH-（3）

2ClO2+HOCl+H2O=2ClO-3+HCl+2H+（4）

TherateofchlorateyieldcanbedescribedbyEquation（5）:

d[CIO3]/dt=2k[ClO2][HOCl]（5）

inwhichk=1.28M/minat25C[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,