Biochar increases biogas production in a batch digester charged with cattle manure

摘要

Twoinvitroincubationexperimentswereconductedtotestthehypothesisthatnbsp;biocharnbsp;wouldserveassupportmediaforbiofilmdevelopmentinanbsp;biodigesterandwouldasaresultnbsp;increasetheyieldofbiogaswhetheraddedseparatelyorenclosedinanylonbagnbsp;Thetreatmentsinexperiment1were:control(nobiochar),biocharaddedat1%ofthesubstrateDMinthebiodigester,biocharaddedat3%ofthesubstrateDMinthebiodigester.Thesubstratewasfreshmanurefromcattlefeddriedcassavaroot,freshcassavafoliageandurea.Proportionsofwaterandmanurewerearrangedsothatthemanureprovided5%ofthesolidsinthebiodigester.Gasproductionwasmeasureddailyoverthefermentationperiodof30days;methaneinthegaswasmeasuredafter21and28days.Inexperiment2,a2*2factorialarrangementwith4replicationswasusedtocomparelevelofbiochar:1%ofsolidsinthedigesterornone;andpresenceorabsenceofaclothbaginthebiodigester.Thefermentationwasfollowedover21dayswithdailymeasurementofgasproductionandcontentofmethaneinthegasattheendofthefermentation.Inexperiment1,incorporationof1%(DMbasis)ofbiocharinthebiodigesterincreasedgasproductionby31%after30daysofcontinuousfermentation;therewerenobenefitsfromincreasingthebiocharto3%ofthesubstrateDM.Themethanecontentofthegasincreasedwiththedurationofthefermentation(24%higherat28comparedwith21days)butwasnotaffectedbythepresenceofbiocharintheincubationmedium.nbsp;Inexperiment2,adding1%ofbiochar(DMbasis)tothesubstrateincreasedgasproductionby35%,reducedmethanecontentofthegasby8%,increasedtheDMsolubilized(by2%)andincreasedmethaneproductionperunitsubstratesolubilizedby25%.Presenceoftheclothbagincreasedgasproductionwhenitalsocontainedbiocharbutdecreaseditwhenaddedtothebiodigesterwithoutbiochar.Therewasasimilarinteractionformethaneproducedperunitsubstratesolubilized.