Dry anaerobic fermentation

The advantages of using high total-solids concentrations for anaerobic fermentations of manures and crop residues are discussed. Studies conducted on dry anaerobic fermentation of organic residues to methane are described. Moisture content, NH/sub 3/-N concentration, and chloride concentration were tested. Anaerobic fermentations occurred in solids concentrations in excess of 20%. At initial concentrations of 40% or less, the reaction will be as complete as for liquid reactors given sufficient time. Above 30% total-solids concentration of manures, methane formation decreased. Acid formation was affected at total-solids levels that were higher than methane formation. A pilot scale batch reactor filled with 25% total-solids substrate of wheat straw, seeded with effluent from a daily manure anaerobic digester, produced methane for over 6 months. (DMC)