Biosorption of chromium and nickel by heavy metal resistant fungal and bacterial isolates
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JournalofHazardousMaterials146(2007)
270–277
Biosorptionofchromiumandnickelbyheavymetal
resistantfungalandbacterialisolates
ShankarCongeevarama,∗,SrideviDhanarania,JoonhongParkb,
MichaelDexilina,KaliannanThamaraiselvia,∗
aDepartmentofEco-Biotechnology,BharathidhasanUniversity,Tiruchirappalli620024,TamilNadu,IndiabSchoolofCivilandEnvironmentalEngineering,YonseiUniversity,Seoul120-749,SouthKorea
Received4May2006;receivedinrevisedform8December2006;accepted9December2006Availableonline13December2006
Abstract
Microorganismsplayasignificantroleinbioremediationofheavymetalcontaminatedsoilandwastewater.Inthisstudy,heavymetalresistantfungiandbacteriawereisolatedfromthesoilsamplesofanelectroplatingindustry,andthebioaccumulationsofCr(VI)andNi(II)bytheseisolateswerecharacterizedtoevaluatetheirapplicabilityforheavymetalremovalfromindustrialwastewaters.TheoptimumpHandtemperatureconditionsforboththegrowthandheavymetalremovalweredeterminedforeachisolate.TheoptimalpHforfungalisolateswaslower(5–5.2)thanthatforbacterialisolates(7).Theobservedeffect(s)ofpHwasattributablemainlytoorganism-specificphysiologybecauseinallthetestedcasesthecellulargrowthpositivelycorrelatedwithheavymetalremoval.Batchandtoleranceexperimentsprovidedinformationforsolidretentiontime(SRT)designandthelethaltolerancelimitsfortheisolatedmicroorganisms.ExperimentalresultsindicatedthatexpandedSRTs(stationaryphase)canberecommendedwhileusingthefungalandbacterialCr-resistantisolatesforremovingchromium.InthecaseofNi-resistantbacterialisolate,anon-expandedSRTwasrecommendedfordesigningcontinuous-flowcompletelystirred(CFCS)bioreactorsothatamid-logphaseofcellulargrowthcanbekeptduringthebioaccumulationprocess.ThetolerancedatawithahighrangeofheavymetalconcentrationsrevealedtheCr-resistantisolates,especiallythefungalone,couldtoleratechromiumtoxicityatupto10,000mgL−1chromium.ResultindicatestheapplicabilityoftheisolatedMicrococcussp.andAspergillussp.fortheremovalofchromiumandnickelfromindustrialwastewater.©2006ElsevierB.V.Allrightsreserved.
Keywords:Fungi;Bacteria;Bioaccumulation;Metalbioremediation;pH;Temperature;Tolerance
1.Introduction
Chromiumandnickelarereleasedintotheenvironmentby
alargenumberofprocessessuchaselectroplating,leathertan-
ning,woodpreservation,pulpprocessing,steelmanufacturing,
etc.,andtheconcentrationlevelsofchromiumandnickelinthe
environmentwidelyvaries.Thesetwometalsareofmajorcon-
cernbecauseoftheirlargerusagesindevelopingcountriesand
theirnondegradabilitynature.Hexavalentchromiumishighly
solubleinwaterandcarcinogenictohuman.Ni(II)ismoretoxic
andcarcinogenicmetalwhencomparedwithNi(IV).Dueto
theirtoxiceffectsonlivingsystemsstringentlimitshavebeen
stipulatedforthedischargeofchromiumandnickelintothe
∗Correspondingauthors.E-mailaddress:chengaishankar@yahoo.co.in(S.Congeevaram).environment.AccordingtoISI:BureauofIndianStandard(BIS)
theindustrialeffluentpermissibledischargelevelofCr(VI)and
Ni(II)intoinlandwateris0.1and3.0mgL−1,respectively.
Conventionalphysicochemicalmethodssuchaselec-
trochemicaltreatment,ionexchange,precipitation,reverse
osmosis,evaporation,andsorption[1,2]forheavymetalremoval
fromwastestreamsarenotcosteffective[3]andhencebiologi-
calapproachhasbeenconsideredasanalternativeremediation
forheavymetalcontamination.Recentlymicrobialsystems
likefungus,bacteriaandalgaehavebeensuccessfullyusedas
adsorbingagentsforremovalofheavymetals[4–7].Micro-
bialpopulationsinmetalpollutedenvironmentsadapttotoxic
concentrationsofheavymetalsandbecomemetalresistant[8].
DifferentspeciesofAspergillus,Pseudomonas,Sporophyticus,
Bacillus,Phanerochaete,etc.,havebeenreportedasefficient
chromiumandnickelreducers[9,10].Theresponseofmicroor-
ganismstowardstoxicheavymetalsisofimportanceinviewof
0304-3894/$–seefrontmatter©2006ElsevierB.V.Allrightsreserved.doi:10.1016/j.jhazmat.2006.12.017S.Congeevarametal./JournalofHazardousMaterials146(2007)270–277271
theirinterestinthereclamationofpollutedsites.Inthepresent
investigation,theabilityofisolatedfungalandbacterialstrains
towardsremediationofchromiumandnickelwasevaluated
bycharacterizingthebioaccumulationofthesemetals.Effect
oftemperature,pH,andtolerancetotheheavymetalsbythe
isolatedorganismswerecarriedout.
2.Materialsandmethods
2.1.Sampling
Soilsampleswerecollectedfroma30-year-oldsmallscale
electroplatingindustryatSipcot,Velloredistrict,TamilNadu,
Indiathatuseschromiumandnickelformetalplating.Inthe
soilsamplecollected,thechromiumandnickelconcentration
wereapproximatelybetween100and50mgL−1,respectively.
Otherreportedliteraturevaluesforcontaminationinsoilare
chromium:4700mgkg−1andnickel:5100mgkg−1[11].The
collectedsampleswerestoredat−80◦Cbeforeanalysis.
2.2.Isolationofmetal-resistantmicroorganisms