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 d igested sludge or pit manure, resulting in different total solids levels, w ere incubated at 35 degrees C. The efficiency of organic matter conversion to methane was found to decrease with increasing organic loads to the diges ters. The highest solids at which the digestion was still feasible was arou nd 10% total solids. Methanogenesis took place at free ammonia (NH3) concen trations of up to 250 mg/l. The efficiency of organic nitrogen conversion t o ammonia (NH3 + NH4+) ranging from 62.6% to as high as 80.3% was achieved in most digestions. (C) 2000 Silsoe Research Institute.