Designation:D7475−11StandardTestMethodforDeterminingtheAerobicDegradationandAnaerobicBiodegradationofPlasticMaterialsunderAcceleratedBioreactorLandfillConditions1ThisstandardisissuedunderthefixeddesignationD7475;thenumberimmediatelyfollowingthedesignationindicatestheyearoforiginaladoptionor,inthecaseofrevision,theyearoflastrevision.Anumberinparenthesesindicatestheyearoflastreapproval.Asuperscriptepsilon(´)indicatesaneditorialchangesincethelastrevisionorreapproval.1.Scope1.1ThismodificationofTestMethodD5526,whichonlyconsideredanaerobicdegradation,isusedtodeterminethedegreeandrateofaerobicdegradation(asindicatedbylossoftensilestrength,molecularweight,possiblyresultingindisin-tegrationandfragmentation)andanaerobicbiodegradationofplasticmaterialsinanacceleratedbioreactorlandfilltestenvironment.Itsimulatesthechangefromaerobictoanaerobicenvironmentsovertimeaslandfilldepthincreases.Plasticmaterialsfoundinlandfillsincludediscardedplasticproductssuchasbagsandwrappersandalsodeliberatelyappliedplasticcoversasinter-layersealersbetweendailyrefusefillstopreventwindblownscatterofgarbageovernightoratotherdowntimes.Thismodificationisatwo-tieredtestmethodinwhichthetwotiers,whichaddressaerobicdegradationandanaerobicbiodegradation,aremostpreferablyrunsequentiallytomorecloselyresembletherealworldconditionofabiologicallyactivelandfill,orabioreactorlandfill,butarefunctionalindependentlyandseparatelydependingontheplasticunderevaluationandtheinformationsought:eitheraerobicdegradationoranaerobicbiodegradationorboth.ThetieredsystemapproachisshownschematicallyinFig.1.InTier1,thetestplasticmaterialismixedwithhouseholdwaste,thenpretreatedandstabilizedaerobicallyinthepresenceofair,inasealedvesselinatemperaturerangethatisconsistentwiththeaveragetemperaturerangeofthoserecordedforlandfillsforatimeperiodoffourweeks.Thetierisanacceleratedsimulationofdegradationwithconcomitantoxygenconsump-tionanddepletionwithtimeasifoxidativedegradationproceeds.InTier2samplesoftheplasticmaterialspretreatedaerobic...
