Performance-of-high-loaded-ANAMMOX-UASB-reactors-c

Performanceofhigh-loadedANAMMOXUASBreactorscontaininggranularsludgeChong-JianTanga,PingZhenga,*,Cai-HuaWanga,QaisarMahmoodb,Ji-QiangZhanga,Xiao-GuangChena,LeiZhanga,Jian-WeiChenaaDepartmentofEnvironmentalEngineering,ZhejiangUniversity,Hangzhou310029,ChinabDepartmentofEnvironmentalSciences,COMSATSUniversity,Abbottabad,PakistanarticleinfoArticlehistory:Received1November2009Receivedinrevisedform28May2010Accepted10August2010Availableonline17August2010Keywords:ANAMMOXGranularcharacteristicsProcessperformanceUASBreactorabstractTheperformanceofhigh-loadedanaerobicammoniumoxidizing(ANAMMOX)upflowanaerobicsludgebed(UASB)reactorswasinvestigated.TwoANAMMOXreactors(R1withandR2withouteffluentrecycling,respectively)werefedwithrelativelylownitriteconcentrationof240mg-NL
1withsubsequentprogressiveincreaseinthenitrogenloadingrate(NLR)byshorteningthehydraulicretentiontime(HRT)tilltheendoftheexperiment.Asuperhigh-rateperformancewithnitrogenremovalrate(NRR)of74.3e76.7kg-Nm
3day
1wasaccomplishedinthelab-scaleANAMMOXUASBreactors,whichwas3timesofthehighestreportedvalue.Thebiomassconcentrationsinthereactorswereashighas42.0e57.7g-VSSL
1withthespecificANAMMOXactivity(SAA)approachingto5.6kg-Nkg-VSS
1day
1.ThehighSAAandhighbiomassconcentrationwereregardedasthekeyfactorsforthesuperhigh-rateperformance.ANAMMOXgranuleswereobservedinthereactorswithsettlingvelocitiesof73e88mh
1.TheANAMMOXgranuleswerefoundtocontainaplentyofextracellularpolymers(ECPs)suchas71.8e112.1mgg-VSS
1ofpolysaccharides(PS)and164.4e298.2mgg-VSS
1ofproteins(PN).Highcontentofhemachrome(6.8e10.3mmolg-VSS
1)wasdetectedintheANAMMOXgranules,whichissupposedtobeattributedtotheiruniquecarminecolor.ª2010ElsevierLtd.Allrightsreserved.1.IntroductionAnaerobicammoniumoxidation(ANAMMOX)isapromisingbiotechnologyforthetreatmentofammonium-richwaste-water(vanderStaretal.,2007;Jossetal.,2009).Underanoxicconditions,theANAMMOXbacteriaaccomplishautotrophicammoniumoxidationtodinitrogengasemployingnitriteasanelectronacceptor(Strousetal.,1998).Itoffersseveraladvan-tagesoverconventionalnitrification-denitrificationsystemsincludinghighernitrogenremovalrate,loweroperationalcostandlessspacerequirement(Jettenetal.,2005;vanderStaretal.,2007;Jossetal.,2009).Combinedwithsinglereactorhighactivityammoniumremovalovernitrite(SHARON)processinwhichhalfofammoniumisconvertedtonitrite,thefirstfull-scaleANAMMOXprocess(70m3)wasappliedtotreatsludgedewateringeffluentsinRotterdam,TheNetherlandsin2002(vanDongenetal.,2001;vanderStaretal.,2007).Itstablyoperatedachievingnitrogenremovalrate(NRR)upto9.5kg-Nm
3day
1(vanderStaretal.,2007).High-rateisoneoftheprimeobjectivesforANAMMOXprocess.TheNRRofconventionalnitrogenremovalbiotech-nologieswaslessthan0.5kg-Nm
3day
1(Jinetal.,2008);whileforANAMMOXprocess,itwashigherthan5kg-Nm
3day
1asobtainedbyanumberofresearchersusingdifferentreactorssuchasupflowbiofilter,upflowanaerobicsludgeblanket(UASB)reactorandgas-liftreactor(Sliekers*Correspondingauthor.Tel./fax:þ8657186971709.E-mailaddresses:[e-mail](C.-J.Tang),[e-mail](P.Zheng).Availableat(2011)135e1440043-1354/$eseefrontmatterª2010ElsevierLtd.Allrightsreserved.doi:10.1016/j.watres.2010.08.018etal.,2003;Imajoetal.,2004;Isakaetal.,2007;vanderStaretal.,2007;Tangetal.,2009a).Todate,thehighestNRRreportedwas26.0kg-Nm
3day
1athydraulicretentiontime(HRT)of0.24h(Tsushimaetal.,2007).Previousworksonanaerobicprocessesincludinganaerobicdigestion(Thieleetal.,1990)anddenitrifyingprocess(Francoetal.,2006)attributedhighvolumetricremovalratestothreemainaspects.Firstly,thereactorsshouldhavehigh-qualitysludgeretentionforsufficientbiomassaccumulation.Secondly,themicrobialcommunitiesshouldaggregateasgranularsludgeorbiofilmsforoptimummetabolicactivity.Finally,thesubstraterequirementsofANAMMOXbacteriashouldbesatisfiedsimultaneouslyavoidingsubstrateinhibition,especiallynitriteinhibition(Strousetal.,1999;Isakaetal.,2007;Tsushimaetal.,2007).Thegranularsludgecharacterizedbygoodsettlingprop-ertyandhighactivityplaysapivotalroleintheperformanceofhigh-ratebioreactors(Thieleetal.,1990;Francoetal.,2006;Zhangetal.,2008).Thecharacteristicsofgranularsludgesuchasheterotrophicaerobicgranules(Beunetal.,1999;Beunetal.,2002;ZhengandYu,2007;Adavetal.,2008),anaerobicgranules(HulshoffPoletal.,2004;Showetal.,2004;Wuetal.,2009),hydrogen-producinggranules(MuandYu,2006;Zhangetal.,2008),denitrifyinggranules(Francoetal.,2006)andautotrophicnitrifyinggranules(Tsunedaetal.,2003;Liuetal.,2008;Belmonteetal.,2009)havebeenextensivelystudied.IncaseofANAMMOXgranules,thesettlingproperty,diameterdistributionandsubstratediffusionhavebeenreported(Arrojoetal.,2006;Nietal.,2009).ThecharacteristicsofcarminecolorofANAMMOXgranulesandtheirassociatedextracellularpolymers(ECPs)havealsodrawnconsiderableattentionfortheprocessoptimization.ThehydroxylamineoxidoreductaseandhydrazineoxidoreductasearetwoimportantenzymesoftheANAMMOXpathway.Bothoftheseenzymesarerichinhemec(Klotzetal.,2008;Schmidetal.,2008),whichendowsth