~tDesignation:D4478-85ReprintedfromtheAnnualBookofASi'MStandards,CopynghtASTMIfnotlistedi!l'fhecurrentcombinedindex,willappearinthenextedition.StandardTestMethodsforOXYGENUPTAKE1ThisstandardisissuedunderthefixeddesignationD4478;thenumberimmediatelyfollowingthedesignationindicatestheyearoforiginaladoptionor,inthecaseofrevision,theyearoflastrevision.Anumberinparenthesesindicatestheyearoflastreapproval.Asuperscriptepsilon(<)indicatesaneditorialchangesincethelastrevisionorreapproval.1.ScopeINTRODUCfiONTheseoxygenuptakemethodsuseadissolvedoxygen(DO)probetomonitortheresponseofanactivatedsludgewhenabiodegradablesubstanceisadded.Anoxygenuptaketestisabioassayconductedunderprescribed,standardconditionsusingmicrobialrespirationtomeasuretheeffectofthematerialbeingtested.Presenceofaninhibitoryortoxicsubstanceinawastewaterbeingtestedadverselyaffectsactivatedsludgeandwouldbereflectedbyareducedrateorcessationofoxygenuptakeortheamountofoxygenconsumed,orboth.Oxygenuptakeresponsesofanacclimatedactivatedsludgemayvaryfromdaytodayevenwhenastandardreferencecompoundisused.Anychangesintheactivityoftheactivatedsludgecanbedeterminedbycomparingresultsobtainedperiodicallyonastandardreferencecompound.Anappropriatereferencecompoundshouldbeaconstituentofthewastewaterbeingtreatedorcloselyrelatedinchemicalstructure.Factorsthatmayaffecttheoxygenuptakeinclude:sourceoftheactivatedsludge,sludgeage,variationsinthetreatmentsystemoffactorssuchaspH,temperature,retentiontime,dissolvedoxygen,concentrationofdissolvedsalts,andcompositionofthewastewater.Activatedsludgeisacomplexmixturewhichincludesmanydifferentgeneraandspeciesoflivingmicroorganisms;itisadynamicecosystemresponsivetoenvironmentalchanges.TestconditionsinthesemethodsareprescribedtominimizevariationsinoxygenuptakeduetopHandtemperaturechanges.Completestabilizationofbiodegradablesubstancesmaytakedaysorevenweekssinceorganicmaterialsvaryinbiodegradability.Additionofabiodegradablesubstratetoactivatedsludgeusuallyresultsinthefollowingsequenceofevents:I....
