PerformanceofANAMMOX-EGSBreactorTingtingChena,PingZhenga,⁎,ChongjianTanga,ShengWangb,ShuangDingaaDepartmentofEnvironmentalEngineering,ZhejiangUniversity,Hangzhou310029,ChinabDepartmentofGeographyandEnvironmentalEngineering,TheJohnsHopkinsUniversity,Baltimore,MD21218,USAabstractarticleinfoArticlehistory:Received31December2010Receivedinrevisedform14May2011Accepted16May2011Keywords:ANAMMOX-EGSBreactorANAMMOXgranulesPerformanceThenitrogenpollutionhascausedseriousenvironmentalproblems.ThemainaimsofthepresentstudyweretoremovethenitrogenfromwastewaterthroughANAMMOX(ANaerobicAMMoniumOXidation)process,andlettheeffluentmeetthedischargestandardwhichwassignificantandadvanceinthefieldofANAMMOXapplicationwhichwasalsoveryimportanttotheenvironmentalprotectionandwaterrecycling.ThisstudyreportstheperformanceofANAMMOX-EGSB(ExpandedGranularSludgeBed)reactorafterfeedingwithsyntheticwastewater.Theresultsshowedthattheeffluentammoniumconcentrationwas11.90mgN/Landthenitrogenremoveefficiency(NRE)reachedupto94.68%whenthevolumetricnitrogenloadingrate(NLR)andvolumetricnitrogenremovalrate(NRR)wereashighas27.31and25.86kgN/(m3·d),respectively.TheeffluentammoniumconcentrationmeetstheChineseintegratedwastewaterdischargestandard(GB8978-1996)inwhichtheammoniumconcentrationshouldbelowerthan15mgN/L.Themaximumammonium,nitriteandnitrogenconversionrates(qmax)bytheANAMMOXgranularsludgeinthereactorwere907.13,841.76,1810.10mgN/(gVSS·d)andhalfsaturationconstants(KS)were2.69,0.44,3.11mgN/L,respectively.©2011ElsevierB.V.Allrightsreserved.1.IntroductionThedischargeofnitrogen-containingwastewatercontributesalottothewaterpollutionandecologicaldeterioration.Accordingtothereportof“thestateoftheenvironmentinChina(2009)”,theammoniumemissionwasupto1.23milliontonsperyear.Nitrogenpollution(N-pollution)causesseriousenvironmentalproblems.Thewaterbloomsandredtidesfrequentlyoccurredandseriouslydisturbedthebalanceofaquaticecosystem.Furthermore,N-pollutionnotonlyharmsthesustainabledevelopmentofagriculture,fisheryandtourismetc.,butalsothreatensthelivingenvironmentofhumanbeings.Thus,itisnecessarytoremovenitrogenfromwastewater.Moreover,duetotheshortageofwaterresource,thenitrogenconcentrationinthedischargedwastewatershouldmeetthedischargestandardafterN-removaltreatment.AccordingtothefirstclassdischargestandardintheChineseintegratedwastewaterdischargestandard(GB8978-1996),theeffluentammoniumconcentra-tionshouldbelowerthan15mgN/L.ANAMMOX(ANaerobicAMMoniumOXidation)processisanovelandpromisingalternativeinthattheaerationandcarbon-sourcedemandreducesbyover50%and100%,respectivelycomparedtoconventionalnitrificationanddenitrificationprocesses[1].Thefirstfull-scaleANAMMOXreactorwasconstructedbytheDokhaven–SluisjesdijkwastewatertreatmentplantinRotterdamin2002,treatingsludgedewateringeffluentfromtheSharon(singlereactorhighactivityammoniaremovalovernitrite)process.Itsmaximumnitrogenremovalrate(NRR)reached9.5kgN/(m3·d)[2],whichwasfarhigherthanthemaximumNRRobtainedfromtheconventionalnitrification–denitrificationprocess(lowerthan0.5kgN/(m3·d))[3].TheestimatedtreatmentcostofANAMMOX–0.75Euro/kgN–wasverylowcomparedto2–5Euro/kgNthatwascalculatedfromanotherpilot-scaletestfornitrogenremovalfromsludgedigestionliquors[4].Gutetal.(2006)[5]alsoinvestigatedtheperformanceofasemi-industrialANAMMOXsystem(2m3),i.e.anANAMMOXmoving-bedbiofilmreactor,andachievedanaveragenitrogenremovalefficiencyof84%.Duetoitscost-effectivenessandhighefficiency,ANAMMOXprocesshasdrawnconsiderableattention.Now,theANAMMOXprocessiswidelyusedinmanyoccasionsandhasagoodprospectfortheapplication.Tolettheammoniumconcentrationintheeffluentreachtheemissionlimitvalue,notonlythetestedreactorshouldhavehighnitrogenremovalperformance,butalsotheANAMMOXgranularsludgeinthereactorshouldpossesshighspecificconversionrateandsubstrateaffinity.SincetheEGSBreactorhasbeensuccessfullyappliedinanaerobicprocesses,itwasintroducedtodeveloptheANAMMOXprocessesinthisstudy.ThispaperreportstheperformanceofANAMMOX-EGSBreactorandthepropertiesoftheANAMMOXgranularsludge.2.Materialsandmethods2.1.SyntheticwastewaterAmmoniumandnitriteweresupplementedtoamineralmediumasneededintheformofNH4ClandNaNO2,respectively.ThecompositionofDesalination278(2011)281–287⁎Correspondingauthor.Tel./fax:+8657186971709.E-mailaddress:pzheng@zju.edu.cn(P.Zheng).0011-9164/$–seefrontmatter©2011ElsevierB.V.Allrightsreserved.doi:10.1016/j.desal.2011.05.038ContentslistsavailableatScienceDirectDesalinationjournalhomepage:(g/Lexceptfortraceelementsolution):KH2PO4,0.01;CaCl2•2H2O,0.18;MgSO4•7H2O,0.30;KHCO3,1.250;EDTA,0.005;FeSO4,0.00625,and1ml/Loftraceelementsolution.Thetraceelementsolutioncontains(g/L):EDTA,15;H3BO4,0.014;MnCl2•4H2O,0.99;CuSO4•5H2O,0.25;ZnSO4•7H2O,0.43;NiCl2•6H2O,0.19;CoCl2•6H2O,0.24;NaMoO4•2H2O,0.22;NaSeO4•10H2O,0.21andNaWO4•2H2O,0.05(adaptedfrom[6]).2.2.ANAMMOXinoculumInoculumwastakenfromalab-scaleANAMMOXreactor.Thesuspendedsolids(SS)andvolatilesuspendedsolids(VSS)oftheinoculumwere40.65and34.82g/L,respectively.Thelab-scaleANAMMOXreactorwasinitiallyino