EPA Method 304A

2004METHOD304A:DETERMINATIONOFBIODEGRADATIONRATESOFORGANICCOMPOUNDS(VENTOPTION)1.0ScopeandApplication.1.1Applicability.Thismethodisapplicableforthedeterminationofbiodegradationratesoforganiccompoundsinanactivatedsludgeprocess.Thetestmethodisdesignedtoevaluatetheabilityofanaerobicbiologicalreactionsystemtodegradeordestroyspecificcomponentsinwastestreams.Themethodmayalsobeusedtodeterminetheeffectsofchangesinwastewatercompositiononoperation.Thebiodegradationratesdeterminedbyutilizingthismethodarenotrepresentativeofafull-scalesystem.TheratesmeasuredbythismethodshallbeusedinconjunctionwiththeprocedureslistedinappendixCofthisparttocalculatethefractionemittedtotheairversusthefractionbiodegraded.2.0SummaryofMethod.2.1Aself-containedbenchtopbioreactorsystemisassembledinthelaboratory.Asampleofmixedliquorisaddedandthewastestreamisthenfedcontinuously.Thebenchtopbioreactorisoperatedunderconditionsnearlyidenticaltothetargetfull-scaleactivatedsludgeprocess.Bioreactortemperature,dissolvedoxygenconcentration,averageresidencetimeinthereactor,wastecomposition,biomassconcentration,andbiomasscompositionofthefull-2005scaleprocessaretheparameterswhichareduplicatedinthebenchtopbioreactor.Biomassshallberemovedfromthetargetfull-scaleactivatedsludgeunitandheldfornomorethan4hourspriortouseinthebenchtopbioreactor.Ifantifoamingagentsareusedinthefull-scalesystem,theyshallalsobeusedinthebenchtopbioreactor.Thefeedflowingintoandtheeffluentexitingthebenchtopbioreactorareanalyzedtodeterminethebiodegradationratesofthetargetcompounds.Theflowrateoftheexitventisusedtocalculatetheconcentrationoftargetcompounds(utilizingHenry'slaw)intheexitgasstream.IfHenry'slawconstantsforthecompoundsofinterestarenotknown,thismethodcannotbeusedinthedeterminationofthebiodegradationrateandMethod304Bisthesuggestedmethod.Thechoiceofanalyticalmethodologyformeasuringthecompoundsofinterestattheinletandoutlettothebenchtopbioreactorarelefttothediscretionofthesource,exceptwherevalidatedmethodsareavailable.3.0Definitions.[Reserved]4.0Interferences.[Reserved]5.0Safety.5.1Ifexplosivegasesareproducedasabyproductofbiodegradationandcouldrealisticallyposeahazard,closelymonitorheadspaceconcentrationofthesegasesto2006ensurelaboratorysafety.Placementofthebenchtopbioreactorsysteminsidealaboratoryhoodisrecommendedregardlessofbyproductsproduced.6.0.EquipmentandSupplies.NOTE:Figure304A-1illustratesatypicallaboratoryapparatususedtomeasurebiodegradationrates.WhilethefollowingdescriptionreferstoFigure304A-1,theEPArecognizesthatalternativereactorconfigurations,suchasalternativereactorshapesandlocationsofprobesandthefeedinlet,willalsomeettheintentofthismethod.Ensurethatthebenchtopbioreactorsystemisself-containedandisolatedfromtheatmosphere(exceptfortheexitventstream)byleak-checkingfittings,tubing,etc.6.1BenchtopBioreactor.Thebiologicalreactionisconductedinabiologicaloxidationreactorofatleast6literscapacity.Thebenchtopbioreactorissealedandequippedwithinternalprobesforcontrollingandmonitoringdissolvedoxygenandinternaltemperature.Thetopofthereactorisequippedforaerators,gasflowports,andinstrumentation(whileensuringthatnoleakstotheatmosphereexistaroundthefittings).6.2Aerationgas.Aerationgasisaddedtothebenchtopbioreactorthroughthreediffusers,whichareglasstubesthatextendtothebottomfifthofthereactordepth.2007Apureoxygenpressurizedcylinderisrecommendedinordertomaintainthespecifiedoxygenconcentration.Installablower(e.g.,DiaphragmType,15SCFHcapacity)toblowtheaerationgasintothereactordiffusers.Measuretheaerationgasflowratewitharotameter(e.g.,0-15SCFHrecommended).Theaerationgaswillrisethroughthebenchtopbioreactor,dissolvingoxygenintothemixtureintheprocess.Theaerationgasmustprovidesufficientagitationtokeepthesolidsinsuspension.Provideanexitfortheaerationgasfromthetopflangeofthebenchtopbioreactorthroughawater-cooled(e.g.,Allihn-type)verticalcondenser.Installthecondenserthroughagas-tightfittinginthebenchtopbioreactorclosure.Installasplitterwhichdirectsaportionofthegastoanexitventandtherestofthegasthroughanairrecyclepumpbacktothebenchtopbioreactor.Monitorandrecordtheflowratethroughtheexitventatleast3timesperdaythroughouttheday.6.3WastewaterFeed.Supplythewastewaterfeedtothebenchtopbioreactorinacollapsiblelow-densitypolyethylenecontainerorcollapsiblelinerinacontainer(e.g.,20L)equippedwithaspigotcap(collapsiblecontainersorlinersofothermaterialmayberequiredduetothepermeabilityofsomevolatilecompoundsthrough2008polyethylene).Obtainthewastewaterfeedbysamplingthewastewaterfeedinthetargetprocess.Arepresentativesampleofwastewatershallbeobtainedfromthepipingleadingtotheaerationtank.Thissamplemaybeobtainedfromexistingsamplingvalvesatthedischargeofthewastewaterfeedpump,orcollectedfromapipedischargingtotheaerationtank,orbypumpingfromawell-mixedequalizationtankupstreamfromtheaerationtank.Alternatively,wastewatercanbepumpedcontinuouslytothelaboratoryapparatusfromableedstreamtakenfromtheequalizationtankofthefull-scaletreatmentsystem.6.3.1RefrigerationSystem.Keepthewastewaterfeedcoolbyiceorbyrefrigerationto4EC.Ifusingableedstr