污水处理-英文文献4

Desalination231(2008)20–260011-9164/08/$–Seefrontmatter©2008ElsevierB.V.AllrightsreservedPresentedatThe4thIWAConferenceonMembranesforWaterandWastewaterTreatmentMay15–17,2007,Harrogate,UK*Correspondingauthor.Upgradingandretrofittingofmunicipalwastewatertreatmentplantsbymeansofmembranebioreactor(MBR)technologyCh.Brepolsa,E.Dorgelohb,F.-B.Frechenc,W.Fuchsd,S.Haidere,A.Jossf,K.deKorteg,Ch.Ruikeng,W.Schierc*,H.vanderRoesth,M.Wetti,Th.WozniakjaErftverband,Bergheim,GermanybPrüf-undEntwicklungsinstitutfürAbwassertechnik(PIA)anderRWTHAachen,GermanycDepartmentofSanitaryandEnvironmentalEngineering-DESEE,UniversityofKassel,GermanyTel.+49(561)8043817;Fax[phone];email:[e-mail]sourcesandAppliedLifeSciences–Vienna,DepartmentIFA-Tulln,InstituteforEnvironmentalBiotechnology,Tulln,AustriaeH2OfficeAbwassertechnik,Wien,AustriafEAWAG—SwissFederalInstituteofAquaticScienceandTechnology,Duebendorf,SwitzerlandgDWR—DienstWaterbeheerenRiolering,Amsterdam,TheNetherlandshDHV—ConsultancyandEngineering,Amersfoort,TheNetherlandsiSüddeutscheAbwasserreinigungs-IngenieurGmbH,Ulm,Germanyjwwsconsulting,Reutlingen,GermanyReceived17May2007;acceptedrevised20November2007AbstractInthefuture,upgradingofexistingwastewatertreatmentplants(wwtps)willbecomethemorechallengingtaskthanerectionofwhollynewplants,asmostoftheplants(e.g.necessaryinGermany)doexistalready.Sincesometime,MBRtechnologyhasbeentakenintoconsiderationandhasbeenrealisedasanalternativeforwwtpupgrading.Thispapergivesanoverviewaboutsomerelevantpreconditions,basicupgradingconceptsandexamplesofalreadyupgradedwwtpsusingMBRtechnology.Keywords:Municipalwastewatertreatment;Upgrading;MBRtechnologydoi:10.1016/j.desal.2007.11.035Ch.Brepolsetal./Desalination231(2008)20–26211.IntroductionManywwtpssufferfromaninadequateleveloftreatmentprovided.Thereareseveralreasonsfortheneedofretrofittedand/orupgradedequip-ment,suchasexpiryoflifespan,theincreaseofwastewaterfloworloadorhighertreatmentstan-dardsduetoachangeoflegalframework.Ingen-eral,nostandardsolutionsfortheupgradingofwastewatertreatmentsystemsareavailableandthetransferofacertainmeasurefromonecasetoanotherislimited.Infact,theoptimumanswerineachindividualcaseislargelysite-dependent.Accordingly,thereisabroadspectrumofmea-suresthatmightbeemployed.Inmostcasesitisnotasingularactiontobetaken,buttheupgrad-ingwillincorporateasetofdifferentinterlockingcomponentsbothatthedrainagesystemandthewastewatertreatmentplant.TheMBRprocessisanemergingadvancedwastewatertreatmenttechnologythathasbeensuccessfullyappliedataneverincreasingnum-beroflocationsaroundtheworld.Itinvolvesasuspendedgrowthactivatedsludgesystemthatutilizesmicroporousmembranesforsolid/liquidseparationasasubstituteoftheconventionalsec-ondaryclarifier.MBRtechnologyhasnotonlyattractedincreasinginterestforthesetupofnewwastewatertreatmentsystemsbutalsoithashighpotentiallookingatupgradingtasksofalreadyexistingwwtps.2.ConsiderationsforthechoiceofMBRtechnologySincemembranefiltrationallowsraisedsludgeconcentrations,theactivatedsludgetankvolumecanbesignificantlyreduced.Incombinationwiththeoptiontoconvertthesecondaryclarifier,thatisnolongerrequiredasasedimentationtank,asanadditionalactivatedsludgetank,thetreatmentcapacityoftheexistingplantcanbelargelyex-tended.Thatwayitispossibletoupgradeexist-ingwwtpsfromsimplecarbonremovaltoBNRsystemsjustusingthealreadyexistingvolume.ThereforefavourableconditionsforthechoiceofMBRtechnologyaregiven,whereretrofittingoftheexistingplantbytheconventionalactivatedsludge(CAS)processwoulddemandforsubstan-tialextensionoftheactivatedsludgevolume.Aswell,wherelimitationsduetoinsufficienteffi-ciencyofthesecondaryclarificationbasinexist,particularlyhowever,wherebothproblemshavetobesolved.MBRtechnologyshouldalsobeconsideredifhigheffluentcriteriasuchasremovalofsuspendedsolidsorabsenceofpathogenshavetobemet.Examplesaredischargeintosmallcreaksaswellasintobathingwaterorothersensitiveareas.DuetothesmallspacerequirementtheMBRoffersspecialadvantagesifthegivenlocationholdsnooronlyalimitedamountofareainre-serve.Moreover,thesmallfootprintallowsacom-pleteindoorinstallationinabuildingdesignedtoblendinwithitssurroundingenvironmentandsuchtoaddressissuesofvisualamenity,odourornoise.AnotherdistinctadvantageofMBRtechnol-ogyisdirectutilisationoftheeffluentforreusepurposes.Thewaterreusepotentialincludesirri-gationofagriculturalland,rechargeofaquifersorriverflowreplenishment.OnseveraloccasionsthiswasthemajordecisioncriteriatooptforMBRtechnology.WiththechoiceoftheMBRspecialattentionshouldbepaidtothefactthattheinvestmentcostsarelargelycorrelatedwiththehydraulicpeakflow.Thisparameterdeterminesthetotalmembranesurfaceareawhichneedstobeinstalled.There-fore,accompanyingmeasurestominimizewetweatherflowortoharmoniseresultantwastewa-terlargelycontributetocosteffectivenessoftheMBRapproach.Oneoptionfordealingwithhighwetweatherpeaksistousetheformersecondaryclarifierasstoragevolume.Anotheroptionishy-bridsystemswheretheconventionalsystemisusedasabackuptotreattheinflowvolumethatexc