AnaerobicDigestion

SybilSharvelleAssociateProfessor

ColoradoStateUniversity

PresentationOverview

• Anaerobicdigestion(AD)process• ADtechnology• Usesforbiogas

AnaerobicDigestionProcess

AnaerobicDigester Liquid

Fertilizer

Compost

CH4

ADProcess

•BiologicalProcess•Applicableforhighorganiccontentwaste

• Inabsenceofoxygen,carbonisconvertedtomethane

•Worksbestat35oC

Source: Renewable Energy Association

ADProcessSchematic

Hydrolysis

Acido/Acetogenesis

Methanogenesis

Solubleorganiccompounds

Methanebiogas

Aceticacid

Biodegradablewaste

TechnologyDependsonWasteQuality

• OrganicFractionMunicipalSolidWaste• Highsolids• InorganicContaminants

• Manure• Dependsonmanagementpractice

• LiquidWastewater(e.g.foodprocessing)• Lowsolidsandhighorganicmatter

MunicipalSolidWastes

MunicipalSolidWastes:LandfillBasedDigester

YoloCounty,California

MunicipalSolidWastes:AdditiontoAnaerobicDigester

EastBayMunicipalUtilityDistrict

https://erams.com/AD_feasibility/

AD:HighOrganicLiquidWasteMaterial

Upflow SludgeBlanket FixedFilm

FixedFilmAnaerobicDigester

0-1%TS

Inlet

Outlet

UpFlowAnaerobicSludgeBlanket

Digester1-5%TS

Inlet

Outlet

SludgeBlanket

NewBelgiumBreweryAnaerobicDigester

RegionalBiodigester:HeartlandBiogas

•WeldCountynearLaSalleCO

•4,700MMBtu•PowerPurchaser:SacramentoMUD

UsesforBiogas

MethaneGas

Cogeneration

Electricity Hot Water

Purification to SupplyNatural Gas Lines Boiler

Purification and

Liquifaction

PurificationforNaturalGasPipeline

• Organics(siloxane),waterremoved

• H2Sreducedto5ppm• CO2 Removal

Source: SEECO

VehicleFuel

Comparision toOtherFuels

Source:NGVA,2009

Fuel LHV (MJ/kg) CO2 (g/kWh) TheoreticalCO2Reduction (%)

Methane/Biomethane 50.0 198.0 29.2

Propane 45.6 236.8 15.3

Butane 45.3 241.2 13.7

Diesel 42.7 267.5 4.3

Gasoline 42.4 279.5 0.0

Summary

• Anaerobicdigestioncreatesvaluableproductsfromwastematerial

• Technologyselectiondependsonwastematerial• Manyusesforbiogas