Enhancement of methane production in the anaerobic digestion of sewage sludges

Conference · Sun Jan 01 04:00:00 EST 1978 · Biotechnol. Bioeng. Symp.; (United States)

OSTI ID:5858832

Spencer, R R

A portion of the research evaluated the effect of powdered activated carbon on stressed anaerobic digesters utilizing a sewage sludge substrate. The addition of carbon resulted in increased methane production and greater process stability. The degree of enhancement appeared to be proportional to carbon concentration over the dose range studied (500 to 10,000 mg/liter). A maximum increase in methane production of about 150% was observed at the highest carbon dose. The effect of 1500 mg/liter carbon, 4000 mg/liter coal, and 4000 mg/liter flyash on relatively unstressed digesters was also examined. Units using a sewage sludge substrate were operated at 10- 20-day SRTs. A 12% increase in methane production was observed in a carbon-dosed digester functioning at a 10-day detection time. Enhancement was not evident with carbon at at 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 acid-forming step was affected. This information will supplement current research at Battelle Pacific Northwest Laboratory aimed 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. 6 figures, 3 tables.

• Research Organization: Battelle Pacific Northwest Labs., Richland, WA
• DOE Contract Number: EY-76-C-06-1830
• OSTI ID: 5858832
• Conference Information: Journal Name: Biotechnol. Bioeng. Symp.; (United States) Journal Volume: 8
• Country of Publication: United States
• Language: English

Related Subjects

09 BIOMASS FUELS
090122* -- Hydrocarbon Fuels-- Preparation from Wastes or Biomass-- (1976-1989)
140504 -- Solar Energy Conversion-- Biomass Production & Conversion-- (-1989)
32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATION
320604 -- Energy Conservation
Consumption
& Utilization-- Municipalities & Community Systems-- Municipal Waste Management-- (1980-)
AEROSOL WASTES
ALKANES
ANAEROBIC DIGESTION
BIOCONVERSION
BIOSYNTHESIS
CARBON
CRYOGENIC FLUIDS
DIGESTION
ELEMENTS
FLUIDS
FLY ASH
HYDROCARBONS
MANAGEMENT
METHANE
NONMETALS
ORGANIC COMPOUNDS
PROCESSING
SEWAGE
SEWAGE SLUDGE
SYNTHESIS
WASTE MANAGEMENT
WASTE PROCESSING
WASTES