DOC

Removal of Cu and Ni by Freee and Immobilized Microalgae

By Geraldine Roberts,2014-09-22 16:11
7 views 0
Removal of Cu and Ni by Freee and Immobilized Microalgaeof,by,Cu,and,Freee

    Removal of Cu and Ni by Freee and

    Immobilized Microalgae

.0MDICALANDENVIRONMENTALSCIENCES5,99108(1992)

    ;RemovalofCuandNibyFreeandImmobilizedMicroalgae

    ;M.H.WONGANDD.C.H.PAK

    ;DepartmentofBiology,HongKongBaptistCollege,224WaterlooRoad,Kowloon,HongKong

    ;ReceivedJanuary5,1991

    ;ThepresentinvestigationevaluatedtheeffectivenessofChlorellacellsinconcentratingCu

    ;andNiintheircellsandtherebyremovingthetwometalsfromsolution.Theremoval

    ;emciencyofthetwometalsbyfreeandimmobilizedalgalcellswerefurtherstudied.(11Four

    ;typesof/orellacells,namelyChlorellapyrenoidosa(26)(fromCarolinaBiologicalSupplies

    ;Company).ChlorellaHKBCland

    2(isolatedfromapollutedstreamreceivingwastewater

    ;fromseveralelectroplatingfactories1andChlorellaHKBC

    3(fromaclcanwaterpond)were

    ;subjectedtodifierentconcentrationsofCuandNiaccordinglyItwasrevealedthatChlorella

    1wasthemosttolerantspeciestoCuandNiasreflectedbytheirhighe;HKBC

    stvaluesof48h

    ;and96h”Highestnoeffectconcentrations”fThehighestconcentrationofthetested

    ;substancethatdoesnotinhibitthegrowthrateofthealga:Cu2andNil0mg/lat48h.Cu2

    ;andNj5at96h).ThiswasfollowedbyC.pyrenoidosa(261andtheneHKBC

    2whileC.

    ;HKBC

    3hadthelowesttolerancetothetwometals(Cu05andNi2at48h:Cu05andN|l ;mg/lat96h).(2)ItwasfurtherrevealedthatCHKBClhadhicrconcentration

    factors

    ;andremovalemcienciesofNi(734963mg/1.16_3l8.7%1andCHKBC

    2hadhigher

    ;concentrationfactorsandr~movalefTicienciesofCu(23l62839mg/1.53.

    766%1when

    ;exposedtolowerconcentrationsofCu(O.5,land2mg/1)andNi(5,10andl3mg/1).(3)By

    ;treatingthefreeandimmobilizedalgalcells(algalcellsentrappedinalginatebeads)with

    ;difrerentconcentrationsofCuandNi.itwasobservedthatfreecellshadhigherconcentration

    ;factorsandremovalefnciencieswhencomparedwithimmobilizedcells(freecells:Cul577

    ;3056mg/l,24.271.4%;Ni355849mg/l,48

    l87%:jmmobilizedcells:Cu453935mg/l,

    ;l3953.2%:Ni244486rag/l,32.11.9%1

    ;INTRoDUCTIoN

    ;Removalofheavymetalsfromelectroplatingrinsewaterpriortotheirdischargeinto

    ;publicseweragesystemshasbecomeanecessityduetothecontinueddeteriorationof

    ;ouraquaticenvironment.HeavymetalssuchasCr,Cu,NiandZnarecommonly

    ;presentintheelectroplatingrinsewaterandtheywillimposedetrimentalconsequences

    ;forthebiotaofthereceivingwaters,notablybivalves(Wongeta1..l98l1. ;Treatmenttechniquesthathavebeenemployedfortreatingelectroplating ;rinsewaterincludeionexchange,reverseosmosis,freezeconcentration,precipitation,

    ;evaporativerecovery,filtration,coagulationandelectrolyticrecovery(Christensen

    ;andDelwiche.1982).Precipitationisbyfarthemostpopularmethodfortreating

    ;heavymetalwastes.althoughitcanbeexpensive.whichisalsoacommonfeaturefor

    ;allothertreatmentmethodsmentionedabove.Potentialtreatmenttechnologythatis

    ;neitherenergyintensivenorexpensivewillbewellworthinvestigating. ;

    ;WONGANDPAK

    ;Theabilityofmicroalgaetotakeupheavymetalsfromtheirsurroundingwaters

    ;(Bentley-MowatandReid,l977;ROSS,l986)suggeststhattheycouldactasapotential

    ;aidinremovingmetalionsfromtheaquaticenvironment.Cellimmobilizationhas

    ;beenoneofthemostinterestingtopicsinmicrobialtechnology.Thetechniqueofcell

    ;immobilizationisalsousefulinavarietyoffieldssuchasbrewing.cheeseproduction.

    ;processingoftextilesandhides,andthefoodandmedicinalindustriesfChibataand

    ;Tosa,1981).Algalcellshavebeensuccessfullyentrappedbyalginate.Thisisa

simple

    ;andcheaptechniquehavingtheadvantagesofeaseofuseandreversiblenaturewitha

    ;highretentionofcellviabilityrDaintyeta1.,l986).

    ;Withtheabovebackground,thepresentinvestigationisaimedatstudying:(1)the

    ;tolerantabilitiesoffourdifierenttypesofClorellacellstovariousconcentrationsof

    ;CuandNi.(2)theabilitiesofthefourtypesofClorellacellsinconcentratingCuand

    ;Ni(concentrationfactor)andinremovingthetwometalsfromtheaqueoussolution

    ;containingthemetals.r31theeffectivenessoftheimmobilized(algalcellsentrappedin

    ;alginatebeads)andfreeChlorellacellsinconcentratingCuandNiandremovingthe

    ;twometalsfromsolution.

    ;MATERIALSANDMETHoDS

    ;FourtypesofChlorellawereusedinthisexperiement:Chlorellapyrenoidosa(26)

    ;obtainedfromCarolinaBiologicalSuppliesCoUSA.Theotherthreewerei

    solated

    ;locally;twoofthemfromaheavilypollutedstreamatTaiWarPing,whichreceives

    ;dischargefromseveraIelectroplatingindustries,aredesignatedasChlorellaHKBC-l

    ;and.2,respectively,andonefromacleanwaterpond,designatedasChlorella ;HKBC.3.TheisolationandmaintenanceproceduresforthealgalsamplesfoUowed

    ;thosedescribedinSteinrl973).

    ;ToxicityTestofCuandNi

    ;Apreliminaryexperimentusingawiderangeofmetalsolutions(coppersulphate

    ;andnickelsulphate)onthegrowthofthefouralgalcultureswasconducted.Theactual

    ;experimentwasthencarriedoutbyplacingtheappropriatevolumesofmetalsolutions

    ;intotheculturemedia(Bristol’smedium)makinguptol00mlwithparticle-fre

    e

    ;deionizedwaterandalgalcellswithaknowndensity:4xl0cells/m1.usingl50ml

    ;conicalflasksasculturevessels.Theculturemedia(Cu:0.5,l,2and5rag/1,Ni:5,l0,

    ;13andl5mg/1)wereaerated(toprovideCO2)throughthecottonplugsplaceda

tthe

    ;mouthsoftheflasks(attherateof31/min).Therewerethreereplicatesforeachmetal

    ;concentrationandfivereplicatesforthecontro1.withouttheadditionofmetal ;solution.ThepHofthemediumwasaajustedto6.5withlHCI/NaOHpriorto ;autoclaving.

    ;Theculturevesselswereplacedunderal6.hlight(1ightintensity:3500lux)/8hdark

    ;cycleat25+2~Cfor7days.ThegrowthratesweredeterminedbyceIlcountsusinga

    ;hemocytometereveryday.Thetoxiceffectofthemetalswasexpressedbythe48hand

    ;96h”Highestnoeffectconcentration”rthehighestconcentrationofthetested

    ;substancethatdoesnotinhibitthegrowthrateofthealga)valueswhichwereobtained

    ;bytheDunnett’stest(Dunnett.1955).comparingthetreatmentmeanswithcontrol

    ;meanstoestablishwhetherthetreatmentwassignificantlydifferentfromfhecontrolat

    ;

    ;REMOVALOFCuANDNiBYMICROALGAE

    ;95%confidencelevel,usingcellcountsasaparameter(Adamseta1.,

;1985)

    ;MetalUptakebytheFourAlgalCultures

    ;l0l

    ;ThefouralgalcultureswereexposedtothefollowingconcentrationsofCuandNi

    ;f.0raperiodof8days:Cu0.5,l,2and5mg/landNi5,10,l3,andl5mg/l,usingthe ;samemethodsdescribedabove.

    ;ThedryweightsofalgalcellsweredeterminedafterbeingfilteredthroughAdvantac

    ;25i/lnlcellulosenitratemembranefilterswith0.45mnporesize.ThecontentsofCu

    ;andNiofthealgalcellsweredeterminedbymixedaciddigestion(cone.nitricacid:

    ;cone.perchloricacidattheratioof2:I.andanalysedbymeansofinductivelycoupled

    ;plasmaspectrophotometry(GrantandEllis,1988).SpectrallinesselectedforNiand

    ;Cuwere221.65amand324.75amrespectively.Recalibrationwasperformedafterl2

    ;sampleshadbeenrunandtheblankwasdeterminedeverytimewhenperforming

    ;recalibration.SpectralinterferenceofZn

;correctionmethod.Concentrationfactors

    ;wascorrectedbytheinterferingelement

    ;ofthetwometals,atdifferentconcentra.

    ;tions,ofthefouralgalcultureswerecalculatedusingthefollowingformula(Trollope

    ;andEvans,1976):

    ;ConcentrationFactor=gmetalremoved/gofalgae

    ;gmetalinsolut|on/mlofsolution

    ;ComparisonofMetalUptakebyFreeandImmobilizedAlgalCells ;ThetwoalgalculturesisolatedfromthepollutedstreamnamelyC.HKBC.1and.2.

    ;wereusedinthepresentstudyduetotheirbetterperformanceinremovingCuandNi

    ;fromculturemediaaddedwiththetwometals.Sodiumalnateextractedfrom ;Laminariahyperborea(BDHChemicalsLtd.,wasusedtoimmobilizethealgalcells.

    ;AIginatebeadsof4.3mmdiameterwereformedbyextrudingthesolutionwithor

    ;withoutalginatethroughasterile5mlsyringe(Adamseta1.,l985). ;Comparisonoffreeandimmobilizedalgalcellsweremadeintermsofmetaluptake

    ;(Cu:l,2and5mg/l;Ni:5,10andl5rag/1)accordingtothefollowingtreatments,

each

    ;intriplicate:(a)MetaIsolutionwithfreealgalcells.fb)MetaIsolutionwithoutalgal

    ;cells.(c)MetaIsolutionwithimmobilizedalgalcellsentrappedinalginatebeads.(d)

    ;Metalsolutionwithalnatebeadsonly.

    ;Erlenmeyerflasksof250mlwereusedasculturevesselseachcontaining85mlof

    ;Bristol’smediumcontaingl,2and5rag/lofCu,and5,l0andl5mg/lofNi,withor

    ;withouttheadditionofalgalcells.immobilizedalgalcells(eelldensity:2×l0f0r

    ;bothfreeandimmobilizedalgalcells.algalcellsentrappedinalginatebeads,lo0beads

    ;intota1)oralginatebeadsalone(alsol00intota1.withoutalgalcells)accordingto

    ;theabovefourtreatments.Thegrowthconditionwasthesameasdescribedintoxicity

    ;testofCuandNi.

    ;ThecontentsofCuandNiofthefreealgalcells(afteraciddigestion)andtheculture

    ;solution(afterfilteringthroughanadvanteccellulosenitratemembraneof0.45m

Report this document

For any questions or suggestions please email
cust-service@docsford.com