35-BioresourceTechnol-UCD

Providedbytheauthor(s)andUniversityCollegeDublinLibraryinaccordancewithpublisherpolicies.Pleasecitethepublishedversionwhenavailable.Downloaded2016-04-13T03:47:30ZTitleUseofdewateredalumsludgeasmainsubstrateintreatmentreedbedreceivingagriculturalwastewater:long-termtrialAuthor(s)Zhao,Y.Q.;Zhao,X.H.;Babatunde,A.O.PublicationDate2009-01PublicationinformationBioresourceTechnology,100(2):644-648PublisherElsevierLinktopublisher'sversion://hdl.handle.net/10197/3137Publisher'sstatementThisistheauthor’sversionofaworkthatwasacceptedforpublicationinJournalofEnvironmentalSciences.Changesresultingfromthepublishingprocess,suchaspeerreview,editing,corrections,structuralformatting,andotherqualitycontrolmechanismsmaynotbereflectedinthisdocument.Changesmayhavebeenmadetothisworksinceitwassubmittedforpublication.AdefinitiveversionwassubsequentlypublishedinBioresourceTechnology,100(2):644-648DOI10.1016/j.biortech.2008.07.040.DOI:Long-termtrial23Y.Q.Zhao*,X.H.Zhao,A.O.Babatunde4CentreforWaterResourcesResearch,SchoolofArchitecture,LandscapeandCivilEngineering,5UniversityCollegeDublin,Newstead,Belfield,Dublin4,Ireland6_________________________________________________7*Authortowhomcorrespondenceshouldbeaddressed:Tel:[phone];Fax:;[phone];8E-mail:[e-mail]910Abstract11Thisstudyaimstoexploreanovelapplicationofdewateredalumsludgecakes(DASC)asthe12mainmediuminasinglemodelreedbedtotreatphosphorus-richanimalfarmwastewater13under“tidalflow”operationonalongtermbasis.Itisexpectedthatthecakesactasthe14carrierfordevelopingbiofilmandalsoserveasadsorbenttoenhancephosphorus(P)15immobilization.Resultshavedemonstratedthataverageremovalefficienciesof73.3±15.9%16forCOD,82.9±12.3%forBOD5,86.4±6.0%forRP(reactiveP),88.6±7.2%forSRP(soluble17reactiveP)and77.6±17.5%forSScanbeachievedduringthetwoyear‟soperation.More18significantly,the“P-adsorptionproportion”byDASCinthereedbedis42%oftheoverallP19removal.TheremainingremovalofPmaybecontributedbythetrappingandfiltration20processofDASC.Therefore,thelifetimeoftheDASCinreedbedisreasonablylongerthan21thatdeterminedfromthebatchisothermtest.22Keywords:Dewateredalumsludge,phosphorus,reedbed,tidalflowstrategy,wastewater23treatment24-2-1.Introduction25Ithasbeenrecognisedandgenerallyacceptedthaturbanization,industrialrevolution,and26deficientwastedisposalpracticeshaveleftalegacyofpollutedsedimentsinwater27environmentincludingrivers,estuaries,lakesandseas.Appropriatedisposalofsuchresultant28wastesinlinewithsustainabledevelopmentremainsagreatchallengetoengineersand29scientistswhoarecalledupontodevelopsolutionsthataretechnically,economically,and30sociallysound.Dewateredalumsludgecakes(DASC)refertotheby-productinwater31industryfrompotablewatertreatmentprocesswherealuminiumsulphateisemployedforthe32rawwaterflocculation.InmostcountriesworldwideincludingIreland,theDASCisregarded33aswasteanddisposedoffinlandfill.Althoughanumberofattemptshavebeenmadeto34beneficiallyreusesuch“waste”asrawmaterialsincivilandenvironmentalengineering35(BabatundeandZhao,2007),uptillnow,landfillremainsthedominantoption.However,itis36notedthatDASCdifferssignificantlyfromotherindustrialwastessuchaspharmaceutical37industrialwasteandpetroleumindustrialwastethatmaycontainhighhydrocarbonsandtoxic38substances.DASCisderivedfromtheresidualofrawwaterwhichcontainsmainlyturbidity,39colourandhumicsubstanceswithnotoxicsubstancesinmostcases,exceptprobablyforthe40arsenicinsomesourcewatersinspecialcircumstances.TwomajorfeaturesoftheDASCare:41(1)highcontentofaluminium(29.7±13.3%bymass(BabatundeandZhao,2007))and(2)its42locally,largelyandeasilyavailablenaturecoupledwiththefactthatitisfreeofcharge.These43makeitpossibletoreusesuchkindofsludgeasavaluableraw/resourcefulmaterialin44wastewatertreatmenttoenhanceadsorptionandchemicalprecipitationprocessesthatremove45variouspollutants,especiallyphosphorus(P).46Ontheotherhand,constructedwetlands(orcommonlyknownasreedbeds)havebeen47usedsuccessfullyworldwideasoneofthemostpopulartechnologiestotreatvarioustypesof48-3-wastewaters(Scholz,2006;Healyetal.,2007;Vymazal,2007,Woodetal.,2007;Babatunde49etal.,2008).Inparticular,reedbedsystemisconsideredtobeefficientandatthesametime50economicallyandenvironmentallyattractiveandsustainable.Inthelastseveralyears,51extensivestudiesatUniversityCollegeDublin,Irelandhavebeenundertakentodevelop52novelapproachesforthepurposeofenhancingpollutantremovalinreedbedtreatment53systems.TheseincludetidalflowoperationstrategyandDASC-basedreedbedsystem.54Theseinnovativeapproacheshavedemonstratedtheimprovedabilityofreedbedsystemsto55enhanceoxygentransferandahighimmobilizationcapacityforPremovalfromthe56wastewater(Sunetal.,2005;Sunetal.,2006;Babatundeetal.,2007;Zhaoetal.,2008).57Tidalflowoperationstrategyisabatch