在纺织废水中脱色细菌的影响外文翻译Word文档下载推荐.docx

在纺织废水中脱色细菌的影响外文翻译Word文档下载推荐.docx

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1DepartmentofHydrologyandWaterResources,HohaiUniversity,Nanjing,China;

2StateKeyLaboratoryofHydrology-WaterResourcesandHydraulicEngineering,HohaiUniversity,Nanjing,China.

Email:

aamralewi@

ReceivedMay12th,2012;

revisedJune15th,2012;

acceptedJuly17th,2012

ABSTRACT

Thestudyaimstoisolateandoptimizebacterialstrainshavingtheabilitytodegradeanddecolorizeazodyesproducedinthefinaleffluentoftextiledyingindustries.Inthisregard,tenbacterialstrainswereisolatedfromwastewatertreat-mentplants,andmostofthemweresubjectedtothecoloredeffluentsresultingfromdilapidatedhouses.Theabilityofthesebacterialisolationstouseawiderangeofazodyestodeterminethesolecarbonsourcewasdetermined.

Keywords:

Decolorization;

Biodegradation;

AzoDys;

TextileWastewater

1.Introduction

Environmentalpollutionhasbeenidentifiedasamajorprobleminthemodernworld.Theincreasingdemandfordrinkablewater,anditsdwindlingsupply,hasmadethetreatmentandreuseofindustrialeffluentsanattractiveoption.Oneofthemostimportantenvironmentalpollu-tionproblemsisthecolorinwatercourses;

althoughsomeofthesecolorsarenormallypresentandof“natu-ral”origins（e.g.thecolororiginatesfromtheactivityofmicroorganismsinponds）,aconsiderableproportion,especiallyinthelowerreachesofriversthatdrainlargeindustrialconurbations,originatesfromindustrialefflu-ents.Somecoloredeffluentsareassociatedwiththepro-ductionanduseofdyes.

Azodyes,thelargestchemicalclassofdyeswiththegreatesvarietyofcolors,havebeenusedextensivelyfortextile,dyeing,andpaperpainting[1].Thesedyescannotbeeasilydegraded,andsomearetoxictohigheranimals.Azodyesconsistofadiazotizedaminecoupledwithanamineorphenol,andcontainoneormoreazolinkages.Atleast300differentvarietiesofazodyesareexten-sivelyusedinthetextile,paper,food,cosmeticsandpharmaceuticalindustries.TheeffectsofpH,temperature,typeandconcentrationofrespirationsubstrates,andoxygentensionontherateofbiologicalreductionofavarietyofazodyeshavepreviouslybeeninvestigated[4,5].Severalcombinationsoftreatmentmethodshavebeendevelopedsofarinordertoeffectivelyprocesscotton-textilewastewater,withdecolorizationamongthemaingoalsfortheseprocesses.

2.Methodology

2.1.IsolationandCultivationoftheMostEfficientDecolorizingBacteria

Sixactivesludgesampleswereobtainedfromthreewastewatertreatmentplants.Allsamplesweretransportedtothelaboratoryandscreenedtoobtainthedyedecolo-rizingorganisms.Allbacterialisolationswerecultivatedonmineralsaltsbasicmediumwiththefollowingcom-position（g/l）:

Na2HPO4,2.13;

KH2PO4,1.3;

NH4Cl,0.5;

MgSO4,0.2;

1Ltapwaterand1mltraceelementsolutionperliter.Thetraceelementsolutionhadthefollowingcomposition（g/l）:

MgSO4·

7H2O,7.12;

ZnSO4·

7H2O,0.044;

MnSO4·

4H2O,0.081;

CuSO4·

5H2O,0.0782;

Na2MoO4·

2H2O,0.025;

FeSO4·

7H2O,0.498;

Boricacid0.1+0.27mlofH2SO4.ThefinalPHwasadjustedat7.0.Themineralsaltsmediumwassupplementedwith1（g/l）yeastextract.Theactivatedsludgesamples（2.5ml）weretransferredinto250mlflaskscontaining50mlmineralsaltsmediumanddye（preparedusingamixtureof9typesofdyes）.Alldyeswaremixedtogethertogetstocksolu-tionofmixtureofdyes0.9（g/l）（0.1g/lofeachdye）.Thestocksolutionwassupplementedwithabasicsaltmediumtogetafinalconcentrationof0.1（g/l）.Eachflaskcon-tained50mlofasterilemineralsaltsliquidmediummixedwithazodyesmixturedispensedwithonegramofyeastextract.Eachflaskwasinoculatedwith2.5mlofactivatedsludge.Allwereincubatedinarotaryincubatorat150rpmfor24hoursat30°

C.Similarflaskswerepreparedandinoculatedwith1mlofthecontentoftheflasksofthefirstgroup.Thesewereincubatedfor24hours.Thisstepwasrepeatedthreetimesinaperiodof72hours.Thelast（third）groupofflaskswasincubatedforfivedays.Theseflaskswereusedtoisolatethetargetmicroorganismsbystreakingamineralsaltsagarmediumcontainingthesameingredientsofthepreviousbrothmedium,plusagarand100ppmofanazodyesmixture.Separatecoloniesofthepredominanttypesofmicroor-ganismswerepurifiedbyre-streakingonthesameme-dium.Thepurifiedisolateswereexaminedmicroscopi-callytocheckforpurity.Obtainedpureculturesweremaintainedonnutrientagarat4°

C（inrefrigerator）[11-13].Tenmorphologicallydifferentisolateswereobtainedfromthepreviousstepandstudiedforcolonymorpho-logy

2.2.ScreeningProgram（Testes）toSelecttheMostPotentOrganisms

Firstscreeningwasdonetotesttheabilityofthepurifiedisolatestoutilizedifferentgroupsofdyesasthesolecarbonsource.Screeningtotesttheabilityofisolatedorganismstoutilizedirectblue75,directblue71,reactiveblue194anddirectred89asthesolecarbonsourcewascarriedoutinamineralsaltsbasicmediumusedinisola-tion.Yeastextractwasreplacedby0.1g/lindividualdye.Organismswereselectedonthebasisoftheirabilitytogrowandreducepigmentationundertheseconditions.Coloniesofanovernightgrowthweresuspendedinnormalsalinetoobtaintheopticaldensityof0.6atwavelength610nm.Onemilliliterofcellsuspensionwasusedtoinoculate100mlbottlescontaining25mlmineralsaltsbasicmediumsupplementedwith0.1g/lindividualdye.Bottleswerethenincubatedforsevendaysat30°

C.Asecondscreeningwasperformedtoensuretheabilityofselectedisolationstoutilizedifferentgroupsofdyesasthesolecarbonsource.

2.3.IdentificationoftheMostPotentofAzoDyes-DecolorizingBacterialIsolates

Thetwomostpotentbacterialisolations（TN1&

TN5）havingthehighestdecolorizationpotentialitywerese-lectedtocompletethestudy.Theywereidentifiedonthebasisofcellshape,cellarrangement,relationtooxygen,nutritionalcharacteristics,physiological,andbiochemicalcharacteristicsintermsofComamanasacidovornsandBurkholderacepace.

2.4.AnalyticalMethods

DecolorizationAssay、DeterminationofTotalProtein、DeterminationofBiochemicalOxygenDemand（BOD）、DeterminationofChemicalOxygenDemand（COD）、UV-Visible,InfraRedandHPLCAnalys

2.5OptimizationofDecolorizationAbilityfortheSelectedIsolates

AdditionofYeastExtract

Oneg/Lyeastextractwassupplementedtothemineralsaltmediumusedinscreeningexperimentsinatrailtosupportgrowthandincreasethedegradationabilityoftheselectedbacterialisolations.TheexperimentproceededintriplicatesatpH7andanincubationtemperatureof30°

Cinbottlescontaining25mlmediumsolution

2.6.DecolorizationunderDifferentCultureConditions

2.6.1.EffectofPHontheDecolorizationofAzoDyesAcidOrange7andDirectBlue75byCom.Acidovorns-TN1andBur.Cepace-TN5

Coloniesofanovernightgrowthweresuspendedinnor-malsalinesolutiontoobtainopticaldensityof0.6g/lat610nmwavelength.Onemilliliterofcellsuspensionwasusedtoinoculate100mlbottlescontaininga25mlmin-eralsaltbasicmedium,supplementedwith0.1g/lindi-vidualdye,and1g/lyeastextract.Themediumwasad-justedtopHof4,6,7,8and9using（1N）hydrochloricacid（HCl）and（1N）sodiumhydroxide（NaOH）.Bottleswereincubatedforsevendaysat30°

C.

2.6.2.EffectofDifferentIncubationTemperatureontheDecolorizationofAzoDyesAcidOrange7andDirectBlue75byCom.AcidovornsTN1andBur.CepaceTN5

Theexperimentwascarriedoutin100mlbottlescon-taining25mlmineralsaltbasicmediumsupplementedwith0.1g/lindividualdyeand1g/lyeastextract.ThemediumwasadjustedtopH8andeachbottlewasinocu-latedwithapredeterminedequalcelldensityforthetwostrains.Bottlesweredividedtobeincubatedatdifferenttemperature:

10°

C,25°

C,30°

C,35°

Cand40°

2.6.3.EffectofDifferentIncubationPeriodsontheDecolorizationofAzoDyesAcidOrange7andDirectBlue75byCom.Acidovorns-TN1andBur.Cepace-TN5

ThisexperimentwascarriedoutinordertoinvestigatetheeffectofdifferentincubationperiodsonthedecolorizationprocessofthetwoazodyesbyCom.acidovorns-TN1andBur.cepace-TN5.Thetwostrainswereallowedtogrowinthetwoazodyesundertheoptimumconditionsdeter-minedfromthepreviousexperiments,andwerethenincubatedfor6,12,24,48,72,120and168hours,re-spectively.Attheendofeachincubationperiod,azodyesdecolorization（%）andtheproteincontentwereassayed.

2.6.4.EffectofDifferentInoculumSizesontheDecolorizationofAzoDyes,AcidOrange7andDirectBlue75,byCom.Acidovorns-TN1andBur.Cepace-TN5

DifferentinoculationsizesofheavycellsuspensionofthetwobacterialisolatesCom.acidovorns-TN1andBur.cepace-TN5（preparedbywashingeachslantwith20mlofsterilesalinesolutionunderasepticconditionsandopticaldensitywasadjustedtoobtainanopticaldensityof0.6at610nmwavelength）wereused.Thefollowinginoculasizeswereappliedvia0.2,0.5,1,2and3mlperflask.Allotheroptimalcultureconditionsweretakenintoconsideration.Attheendofincubationperiodtheazodyesbiodegradationweredeterminedforeachflaskaspreviouslymentioned.

2.6.5.EffectofDifferentCarbonSourcesontheDecolorizationofAzoDyesAcidOrange7andDirectBlue75byCom.Acidovorns-TN1andBur.Cepace-TN5

Differentcarbonsourceswereintroducedintothetwoazodyesmineralsaltsmediaatanequimolecularlevellocatedat0.5g/l.Aparallel