biodeterioration of cementitious materials in biogas digester

1、BiodeteriationofcementitiousmaterialsinbiogasdigesterC.Voegel12A.Bertron1B.Erable21.UniversitdeToulouseUPSINSALMDC(LabatoireMatriauxetDurabilitdesConstructions)135avenuedeRangueilF31077ToulouseCedex04France2.UniversitdeT

2、oulouseINPTUPSCNRSLabatoiredeGnieChimique4AlleEmileMonso31432ToulouseFranceAbstractInbiogasproductionplantsconcretestructuressufferchemicalbiologicalattacksduringtheanaerobicdigestionprocess.Theattackonconcretemaybelinke

3、dtotheeffectsof(i)ganicacids(ii)ammoniumCO2coproducedbythemicroganisms’metabolisms(iii)thebacteria’sabilitytofmbiofilmsontheconcretesurface.Inacontextofbiogasindustryexpansionthemechanismsofconcretedeteriationneedtobebet

4、terunderstoodindertoproposeinnovativeefficientsolutions.Thisstudyaimsfirstlytoacterisetheevolutionofthebiochemicalcompositionofthebiodegradablewastesduringdigestionsoastoidentifythecompoundsthatareaggressivefconcrete.Sec

5、ondlyitaimstoevaluatethemechanismsofconcretedeteriationinanaerobicdigesters.CEMIpastespecimenswereimmersedinsyntheticinoculatedbiowasteinanaerobicdigestionconditions.Theliquidfractionswereanalysedchemically.Thealteration

6、mechanismsofthecementitiousmatriceswereinvestigatedusingXRDSEManalyses.Themaximaltotalconcentrationofganicacidswas65mmolLintheliquidfractionduringthedigestionprocess.ThepHevolutionshowedtwophases:acidificationinthefirstf

7、ewdaysthenaslowincreasetopH78.Inonly6weeksanabundantbiofilmdevelopedonthecementpastesurface.Biodeteriationleadstocalciumleachingcarbonationofthecementpaste.iginalityTodaytheconstructionofnewstructuresinthebiogasfieldisra

8、pidlyexping.FexampleaccdingtotheFrenchganizationADEMEthenumberofanaerobicdigesterinstallationsshouldbemultipliedby6between20102020inFrance.Thiswkaimstoacterizetheaggressivenessofanaerobicdigestionconditionsonconcretestru

9、cturestoensurethesustainabledevelopmentofthisnewdynamicfield.Indeedthebiodeteriationofcementbasedmaterialinanaerobicdigestionispolyacterized.Thestudyofbiodeteriationinbiogasstructureswillcontributetohighlightmechanismsof

10、biodeteriationoncementitiousmaterialinagriculturalagroindustrialenvironments.Keywds:AnaerobicdigestioncementitiousmaterialsbiodeteriationganicacidsmicrostructureCrespondingauth:Tel.:0561559931Fax:056155994932.Materialsme

11、thods2.1CementitiousmaterialsCEMI52.5cementpastesweremadewithawatercementratioof0.40.Thespecimenswerecastincylindricalmoulds75mmhigh25mmindiameter.Thepasteswereremovedfromtheirmoulds24hafterpouringstedinwaterat20Cf28days

12、.2.2PreparationofsyntheticbiowasteAmodelofbiowasterepresentativeoftheganicdomesticwasteproducedinFrancewaspreparedaccdingtoaprocessprovidedbyIRSTEAofAntony(France).Thecompositionofthemodelsyntheticbiowastewas(bymass):pot

13、atoes(8.1%)tomatoes(3.4%)mincedmeat(8.1%)milkpowder(0.7%)crackers(4.1%)water(75.6%).Thewholemixturewasblendedf10minat20Ctoobtainahomogeneousmixture.Thebiowastewasmicrobiologicallyinoculatedtoinitiatetheanaerobicdigestion

14、(Boulangeretal.2012Elbeshbishyetal.2012GonzlezFernndezGarcaEncina2009Hashimoto1989Nevesetal.2004Raposoetal.2006Rzsnetal.2012).ThemicrobialinoculumwassludgecollectedfromamunicipalwastewatertreatmentplantinToulouse(France)

15、.Theganicloadsexpressedaschemicaloxygendems(COD)wereabout50gLfthebiowaste20gLfthesludge(inoculum).Intheliteratureseveralratiosofinoculationcrespondingoftheratiosbetweenthequantityofinoculumthequantityofbiowaste(mm)arerep

16、tedtoensureasuccessfulanaerobicdigestionprocess(Boulangeretal.2012ChenHashimoto1996Elbeshbishyetal.2012Hashimoto1989).InourwkthestrategyofsludgeinoculationwasadaptedfromtheprocedureofElbeshbishyetal.(Elbeshbishyetal.2012

17、)inwhicharatioof1gCOD(Inoculum)gCOD(biowaste)wasused.Thebieacts(usablevolume:500mL)weremaintainedat37Cinanoperatingmodeovenduringthewholeexperiment(Figure1).2.3Cementpasteimmersioninfermentedbiowasteunderanaerobicdigesti

18、onconditionsThecementpastespecimenswereimmersedinbieactscontainingtheinoculatedbiowastef6weeksat35C(Khanal2009Lettinga1995).Thespecimenwasimmersedimmediatelyafterthesludgeinoculationofthebiowaste.Cementpasteswereexposedt

19、oallthesuccessivedegradationreactionsofthebiowasteduringanaerobicdigestion.Thesolidliquidratio(cementpastesurfaceareainoculatedbiowastevolume)feachbieactwasapproximately224cm2.L1(theinsituratioinastarddigesterisapproxima

20、tely4cm2.L1).Controlbieactscontaininginoculatedbiowastewithoutcementpastespecimenswerealsorunf6weeksasreferencetests.ThepHwascontinuouslymeasuredusingapHdataacquisitionsystem(WTWMulti3430).Figure1:(a)Pictureoftheexperime