Amicrobialfuelcellmembranebioreactorintegratedsyst

Amicrobialfuelcell–membranebioreactorintegratedsystemforcost-effectivewastewatertreatmentYong-PengWanga,Xian-WeiLiua,Wen-WeiLib,⇑,FengLib,Yun-KunWangb,Guo-PingShengb,RaymondJ.Zengb,Han-QingYubaSchoolofEarthandSpaceSciences,UniversityofScienceandTechnologyofChina,Hefei230026,ChinabDepartmentofChemistry,UniversityofScienceandTechnologyofChina,Hefei230026,ChinaarticleinfoArticlehistory:Received9January2012Receivedinrevisedform9March2012Accepted12March2012Availableonline28April2012Keywords:Microbialfuelcell(MFC)Membranebioreactor(MBR)WastewatertreatmentBio-cathodeLow-costabstractMicrobialfuelcell(MFC)andmembranebioreactor(MBR)arebothpromisingtechnologiesforwastewa-tertreatment,butbothwithlimitations.Inthisstudy,anovelMFC–MBRintegratedsystem,whichcom-binestheadvantagesoftheindividualsystems,wasproposedforsimultaneouswastewatertreatmentandenergyrecovery.ThesystemfavoredabetterutilizationoftheoxygenintheaerationtankofMBRbytheMFCbiocathode,andenabledahigheffluentquality.Continuousandstableelectricitygeneration,withtheaveragecurrentof1.9±0.4mA,wasachievedoveralongperiodofabout40days.Themaximumpowerdensityreached6.0Wm3.Moreover,low-costmaterialswereusedforthereactorconstruction.Thisintegratedsystemshowsgreatpromiseforpracticalwastewatertreatmentapplication.2012ElsevierLtd.Allrightsreserved.1.IntroductionMicrobialfuelcells(MFCs)aredevicesthatusebacteriaascat-alyststooxidizevarioussubstratesandrecoverelectricity[1,2].MFCsarepromisingforwastewatertreatmentprocesses,buttoachievepracticalapplicationtherearestillmanytechnicalandcostobstaclestoovercome[3].OneapproachtoreducethebarriersandimproveitsapplicabilityistoincorporateMFCintoexistingwaste-watertreatmentprocesses[4,5].Inthisrespect,acontinuous-flowmodeofoperationisusuallyadopted,whichisregardedasmoresuitableforpracticalwastewatertreatmentandMFCapplication[6].AnintegrationofMFCwithconventionalactivatedsludgepro-cesswasfirstreportedbyChaetal.[7].Inthissystem,anaerationtankwasdirectlyusedasthecathodechamber,wheretheaerobicbiofilmdevelopedonthecathodeserveaslow-costandself-sus-tainablecatalyst.Tosupportacontinuous-flowoperation,theaer-ationtankwasfollowedbyaclarifier,andsettledsludgewascontinuouslyreturned.However,thissetupincursadditionalcostfortheclarifierconstructionandsludgepumping.Comparedwiththisdesign,aMFC–membranebioreactor(MBR)integrateddesignappearedtobemoreattractiveintermsofcostsandfootprint[8].MBRspresentahigh-efficienttechnologyforwastewatertreat-ment,andrecentlythedevelopmentofcoarsefilterMBRshavesig-nificantlyloweredtheoperatingcostandpromoteditswidespreadapplication[9–14].Anovelbioelectrochemicalmembranereactor,whichmakesadvantageofbothaMBRandaMFCprocess,wasre-centlyreportedtoachieveamaximumpowerdensityof4.35Wm3andgoodpollutantremovalperformanceattributedtothehighbiomassretentionandsolidrejection[8].Nevertheless,thatsystemhasauniqueandcomplexreactordesign.Specifically,astainlesssteelmeshwasused,whichplayedadualfunctionoffil-terandMFCcathode.Thus,theapplicationofotherless-conductivecoarsematerialswouldbelimitedinthatsystem.Inaddition,theremightbedifficultiesfortheintegratedsysteminkeepinganappro-priateandbalancedbiofilm,whichserveasboththebiocatalystofMFCandthefiltration/foulinglayerofMBR.Allthesemakeitdif-ficulttobedirectlyincorporatedintotheexistingMBRfacilitiesanditspracticalapplicationmightbelimited.Therefore,inthisstudywedevelopamorepracticalMFC–MBRintegratedprocess,inwhichtheaerationtankofaMBRwasdi-rectlyusedasthecathodechamber.Carbonfeltwasusedasthecathodetofavorbiofilmdevelopment.Inordertofurtherreducetheinvestmentandoperatingcost,low-costnylonmeshwereadoptedhereasthefiltermaterial.ThesuitabilityofsuchmaterialsasMBRfilterhavebeendemonstratedinseveralpreviousstudies[8,14,15].ThisworkaimstoinvestigatethefeasibilityofapplyingarelativelysimpleMFC–MBRintegratedsystemforcontinuouswastewatertreatmentandpowergeneration.0306-2619/$-seefrontmatter2012ElsevierLtd.Allrightsreserved.⇑Correspondingauthor.Tel.:[phone];fax:[phone].E-mailaddress:[e-mail](W.-W.Li).AppliedEnergy98(2012)230–235ContentslistsavailableatSciVerseScienceDirectAppliedEnergyjournalhomepage:–MBRsystemThediagramoftheintegratedMFC–MBRsystemisshowninFig.1.Anon-wovenfabric(density,400gm2)wasusedastheseparatoroftheMFCpart.Priortouse,thenon-wovenfabricswerefirstsoakedinpolytetrafluoroethylenesolution(15wt.%)for15min,thendriedat105Cfor180mintopreventwaterleakage.Theanodicchamber(80mL,4cm4cm5cm)wasfilledwithself-fabricatedactivatedcarbonfiber[16].Theaerationtank,withavolumeof20L,wasuseddirectlyasthecathodechamber.Acar-bonfelt(SanyeCarbonCo.,China)withthethicknessof0.6cmandprojectedareaof90cm2wasusedasthecathodewithoutanypre-treatmentandwaswrappedonthenon-wovencloth.Theanodeandcathodewereconnectedthrougha50Xresistorandthevolt-ageswererecordedautomaticallyevery10minusingadataacqui-sitionsystem(USB2801,ATDCo.,China).FortheMBRpart,thenylonmeshwithaporesizeof74lmwasusedasthefiltermater