Methanogenic bacteria were isolated from mesophilic anaerobic digesters. The isolates were able to utilize H2 and CO2 acetate, formate and methanol, but were not able to metabolize propionate and butyrate. It was shown the propionate and butyrate are not substrates for methanogenic bacteria but are converted to hydrogen, carbon dioxide and acetate by a hydrogenic microflora. The reactions leading to methane were quantitatively analyzed. It was shown that acetate, propionate and butyrate metabolism were inhibited by hydrogen. The formation of acetate and propionate were shown to be rate limiting in the digestion process, and that sludge digestion was not inhibited by hydrogen under conditions of excess substrate.

Includes bibliographical references (pages 76-78). Prepared for U.S. Environmental Protection Agency, Office of Research and Development, Municipal Environmental Research Laboratory, Cincinnati, Ohio, submitted by the University of Florida, under grant no. Contract Number: 17070-DJV.

Compares bituminous coal, anthracite, and briquets. Gives the results of tests and presents data for determining relative value of fuels for use in house heating boilers.