不同曝气时长运行下MBBR启动阶段生物膜的形成

AcceptedManuscriptTitle:BiofilmformationmonitoredbyconfocallaserscanningmicroscopyduringstartupofMBBRoperatedunderdifferentintermittentaerationmodesAuthors:Yan-QinGu,Ting-TingLi,Hui-QiangLiPII:S1359-5113(18)30788-8DOI::PRBI11443Toappearin:ProcessBiochemistryReceiveddate:24-5-2018Reviseddate:15-8-2018Accepteddate:30-8-2018Pleasecitethisarticleas:GuY-Qin,LiT-Ting,LiH-Qiang,BiofilmformationmonitoredbyconfocallaserscanningmicroscopyduringstartupofMBBRoperatedunderdifferentintermittentaerationmodes,ProcessBiochemistry(2018),fileofanuneditedmanuscriptthathasbeenacceptedforpublication.Asaservicetoourcustomersweareprovidingthisearlyversionofthemanuscript.Themanuscriptwillundergocopyediting,typesetting,andreviewoftheresultingproofbeforeitispublishedinitsfinalform.Pleasenotethatduringtheproductionprocesserrorsmaybediscoveredwhichcouldaffectthecontent,andalllegaldisclaimersthatapplytothejournalpertain.1BiofilmformationmonitoredbyconfocallaserscanningmicroscopyduringstartupofMBBRoperatedunderdifferentintermittentaerationmodesYan-qinGu,Ting-tingLi,Hui-qiangLi*CollegeofArchitectureandEnvironment,SichuanUniversity,Chengdu610065,China.E-mail:[e-mail].+8618980668020GraphicalAbstractHighlightsStartupcomparisonbetweencontinuousaerationandintermittentaerationMBBRRepresentationofbiofilmformationbyconfocallaserscanningmicroscopyIAMBBRacceleratedthestartupstagebyenhancingtherate-limitingstepPolysaccharidebenefittedtheattachmentofbiomassduringbiofilmgrowthParticulargeneraachievedintheintermittentaerationmodeof3h/3hAbstract:Threeintermittentaerationmovingbedbiofilmreactors(IAMBBRs)withthecyclesofoxicandanoxicconditionsof5h/1h,3h/3h,1h/5handacontinuousaerationMBBR(CAMBBR)wereoperatedsimultaneouslytoobservethesimilaritiesanddifferencesbetweenACCEPTEDMANUSCRIPT2intermittentaerationandcontinueaerationduringstartupstage.Confocallaserscanningmicroscopy(CLSM)wasadoptedtostudytheprocessofbiofilmformation.TheIAMBBRacceleratedthestartupofMBBReffectivelybyenhancingtherate-limitingstepofbiofilmformation.Themicrobestendedtosecretepolysaccharidepreferentiallyafterattachment,andtheprimarygenusvariedfromaerobicbacteriatoanaerobicbacteriawiththereductionofaerationtimeandthedominantdenitrifyingbacterialgenusalsochanged.Biomassconcentrationandtheprotein/polysaccharide(PN/PS)ratioofbiofilmwerethehighestinthemodeof3h/3h,andSphaerotilus,Brevifollis,andSaccharibacteria_genera_incertae_sediswerethedominantgenera.Inbrief,theintermittentaerationcouldacceleratethestartupofMBBReffectively.Keywords:intermittentaeration;movingbedbiofilmreactor;startup;confocallaserscanningmicroscopy;extracellularpolymericsubstances1IntroductionNowadays,movingbedbiofilmreactor(MBBR)hasbeenwidelyusedtotreaturbanandindustrialwastewaterandretrofitexistingwastewatertreatmentplantsduetotheadvantagesofhightreatmentefficiency,simpleandrobustoperationprocedure,lowmaintenanceandreplacementcostandnoincreaseinrunningandcapitalcostsduringretrofit,etc.[1].However,slowbiofilmformationrateduringstartupstageisoneofthestumblingblocksonthepracticalapplicationsofMBBR.ACCEPTEDMANUSCRIPT3Biofilmformationisadynamicprocesscoupledwithattachment,growthanddetachmentofmicrobe.Generally,biofilmformationprocessincludes:(1)initialattachmentofplanktonic,whichhappenswithinseveralhoursafterthecarriersareaddedtothemixedliquorandthecompositionofmicrobialcommunityonthecarriersissimilartotheinoculatedsludge;(2)microbialaccumulation,duringwhichstagemicrobesmultiplyquicklyandit’stherate-limitingstepofbiomassaccumulation.Besides,themicrobialcommunityinthisstageisdifferentfromattachmentstage;(3)biofilmdetachmentandupdating,duringwhichstagethebiomassconcentrationbecomesfluctuation,andthemicrobialcommunitychanges;and(4)maturation,thebiomassconcentrationandmicrobialcommunitycompositionkeeprelativestable[2,3].Factorssuchasmaterialandshapeofcarriers,pH,nutrientlevels,iron,oxygen,temperature,microbialactivity,extracellularpolymericsubstances(EPS)concentration,etc.playimportantrolesinformationrateandmicrobialcommunitycompositionofbiofilm[2].SomestudieshavestudiedtherapidstartupofMBBR,amongwhichinoculation,bio-carriersmodificationandincreaseoforganicloadingratearecommonmethods.Inoculationandbio-carriersmodificationmainlyaffecttheinitialattachmentofplanktonic,andalsoplayimportantrolesintheenrichmentofspecialbacteria[4,5].Enhancementoforganicloadingratecanacceleratetheproliferationofbiomassinbio-carriers,however,theproliferationofautotrophicmicroorganismsisdisappointing[6],anditisalsonotcost-effectiveinthestartupofmunicipalwastewatertreatmentplant.Inaddition,asfarasweknow,thereisnosuitablemethodthatcanenhancetherate-limitingstepeffectivelyduringMBBRstartupstage.ACCEPTEDMANUSCRIPT4IntermittentaerationisaninnovativemodeofoperationfortheMBBR,whichintroducesacycleofoxicandanoxicconditionsinthesamereactor.Theintermittentaerationprovidesacomplexenvironmentthatallowsbothnitrificationanddenitrificationspeciescoexisting