Enhancement of methane production in the anaerobic digestion of sewage sludges [electronic resource].

Published:: Columbus, Ohio : Battelle Memorial Institute, 1978.
Oak Ridge, Tenn. : Distributed by the Office of Scientific and Technical Information, U.S. Dept. of Energy.
Physical Description:: Pages: 22 : digital, PDF file
Additional Creators:: Battelle Memorial Institute and United States. Department of Energy. Office of Scientific and Technical Information

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Summary:

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.

Report Numbers:

E 1.99:pnl-sa-6807
E 1.99: conf-780549-6
conf-780549-6
pnl-sa-6807

Subject(s):

Biomass Fuels

Other Subject(s):

Note:

Published through SciTech Connect.
05/10/1978.
"pnl-sa-6807"
" conf-780549-6"
Symposium on biotechnology in energy production, Gatlinburg, TN, USA, 10 May 1978.
Spencer, R.R.

Funding Information:

EY-76-C-06-1830

View MARC record | catkey: 13819971