High solid anaerobic digestion of chicken manure

Anaerobic digestion of high solids chicken manure was conducted in a batch screening assay. Different mixtures of the fresh manure and anaerobically digested sludge or pit manure, resulting in different total solids levels, were incubated at 35 degrees C. The efficiency of organic matter conversion to methane was found to decrease with increasing organic loads to the digesters. The highest solids at which the digestion was still feasible was around 10% total solids. Methanogenesis took place at free ammonia (NH3) concentrations of up to 250 mg/l. The efficiency of organic nitrogen conversion to ammonia (NH3 + NH4+) ranging from 62.6% to as high as 80.3% was achieved in most digestions. (C) 2000 Silsoe Research Institute.