Enhancement of methane production in the anaerobic digestion of sewage sludges

Conference · Wed May 10 04:00:00 EDT 1978

OSTI ID:6393168

Spencer, R. R.

The effect of powdered activated carbon on stressed anaerobic digesters utilizing a sewage sludge substrate was evaluated. The addition of carbon resulted in increased methanee production and greater process stability. The degree of enhancement appeared to be proportional to carbon concentration over the dose range studied (500-10,000 mg/l). A maximum increase in methane production of about 150% was observed at the highest carbon dose. The effect of 1500 mg/l carbon, 4000 mg/l coal, and 4000 mg/l flyash on relatively unstressed digesters was also examined. Units using a sewage sludge substrate were operated at 10 and 20 day SRT's. A 12% increase in methane production was observed in a carbon dosed digester functioning at a 10 day detention time. Enhancement was not evident with carbon at a 20 day SRT. No significant improvement in methane production was obtained in any of the digesters using coal or flyash as additives. Using the experimental data, a technique was developed for estimating the efficiencies of the methane forming and acid forming steps in the anaerobic digestion process. The results indicated that in stressed systems both stages of the digestion process were enhanced by the addition of powdered carbon. In the relatively unstressed systems, when enhancement did occur, only the scid forming step was affected. This information will supplement current research at determining the mechanism(s) by which carbon enhances the digestion process.Based on the results of this study, it appears that the benefits of carbon addition are greatest in stressed systems. Only very moderate increases in methane production would probably be attainable in well operating digesters. Coal and flyash do not seem to be effective in enhancing gas production in unstressed systems. However, their effectiveness has not been tested in stressed situations.

• Research Organization: Battelle Pacific Northwest Labs., Richland, WA (USA)
• DOE Contract Number: EY-76-C-06-1830
• OSTI ID: 6393168
• Report Number(s): PNL-SA-6807; CONF-780549-6
• Country of Publication: United States
• Language: English

Related Subjects

09 BIOMASS FUELS
090122* -- Hydrocarbon Fuels-- Preparation from Wastes or Biomass-- (1976-1989)
ACETIC ACID
AEROSOL WASTES
ALKANES
ANAEROBIC DIGESTION
BIOCHEMICAL REACTION KINETICS
BIOCONVERSION
BIOSYNTHESIS
CARBON
CARBONACEOUS MATERIALS
CARBOXYLIC ACIDS
CHEMICAL REACTION YIELD
COAL
CRYOGENIC FLUIDS
DATA
DATA FORMS
DIGESTION
ELEMENTS
ENERGY SOURCES
EXPERIMENTAL DATA
FLUIDS
FLY ASH
FOSSIL FUELS
FUELS
GRAPHS
HYDROCARBONS
INFORMATION
ISOLATED VALUES
KINETICS
MANAGEMENT
MESOPHILIC CONDITIONS
METHANE
MONOCARBOXYLIC ACIDS
NONMETALS
NUMERICAL DATA
ORGANIC ACIDS
ORGANIC COMPOUNDS
PROCESSING
REACTION KINETICS
SEWAGE
SEWAGE SLUDGE
SYNTHESIS
WASTE MANAGEMENT
WASTE PROCESSING
WASTES
YIELDS