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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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
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