Methods-for-Quantifying-Lime-Incorporation-into-Dewatered-Sludge.-I-Bench-Scale-Evaluation

MethodsforQuantifyingLimeIncorporationintoDewateredSludge.I:Bench-ScaleEvaluationJasonM.North1;JenniferG.Becker2;EricA.Seagren,A.M.ASCE3;MarkRamirez4;andChristopherPeot,P.E.5Abstract:Theadditionofalkalinematerial�usuallylime�totreatedmunicipalsludgecanbeusedtoraisethepHto�12andgenerateClassAorBbiosolids.Whenlimeisaddedtodewateredsludge,itmustfirstbemadeintoaslurrybeforethepHcanbemeasuredtodemonstrateregulatorycompliance.Inthisstudy,pH12wasachievedinslurriespreparedfromlime-amendeddewateredsludge,evenwhenthelimewaspoorlyincorporatedandrelativelyhighfecalcoliformlevelsweredetected.Thus,quantitativeindicatorsoflimeincorporationareneededtocomplementslurrypHmeasurementsandensurethatsufficientcontactoccursbetweenlimeandsludgeparticlestoachieveadequatestabilization.Inthisstudy,theusefulnessofseveralpotentialmeasuresoflimeincorporation—pH,CO2consumption,distributionofcalcium,fecalcoliforms,NH3andreducedsulfurcompoundproduction,andATP—wassystematicallyevaluatedusingabench-scalesystem.SludgepHandCO2consumptionwerenotinfluencedbytheextentoflimeincorporation.Thedistributionofcalciumandfecalcoliformlevelsappeartobeusefulmeasuresoflimeincorporation.NH3andreducedsulfurcompoundemissionsandATPlevelscanalsobeusedtoassesslimeincorporationprovidedrecommendedexperimentaltechniquesareused.DOI:10.1061/�ASCE�0733-9372�2008�134:9�750�CEDatabasesubjectheadings:Sludge;Lime;Mixing;Full-scaletests;Dewatering;pH;Laboratorytests.IntroductionIncorporationofalkalinematerial,especiallylime,intomechani-callydewateredmunicipalwastewatersludge�postlimestabiliza-tion�canbeusedtoproducematerialsthatmeettheU.S.EnvironmentalProtectionAgency�USEPA�minimumcriteriaforClassBorAbiosolids�USEPA1993�.TomeettheClassBPro-cessestoSignificantlyReducePathogens�PSRP�requirementforlime-stabilizedbiosolids,levelsofindicatororganismsinthesematerialsmustfallwithinmaximumallowablelimits,andthepHofthebiosolidsmustbemaintainedat12for2handat11.5foranadditional22h.AchievementofthepHcriterionisdemon-stratedbymakingmeasurementson