Acetoclastic and Hydrolytic Activity in Anaerobic Digestion--Keys to Process Stability and Process Control

University Of Washington, Seattle WA

Investigators

Abstract

0332118 Ferguson Digestion involves a complex microbial community with sequential conversion of substrates and interdependencies among the populations. The disintegration and hydrolysis of particulate organics has often been thought to limit overall solids degradation in digestion, and methane production from acetate has long been linked to process stability. These processes are directly connected because hydrolysis and fermentation produce acetate and acetate-using (acetoclastic) methanogens consume it. The rate of production can exceed the rate of consumption leading to acetate (and other short chain fatty acids) accumulation, decreases in pH, to inhibition or toxicity, and to process upset. The project is based on two hypotheses about these processes: __ Acetoclastic methanogenesis in most digesters is dominated by low u max, low Ks microbes (e.g. Methanosaeta), resulting in digesters with little reserve capacity to use acetate. __ Conversion of particulate organics, which produces acetate via disintegration or hydrolysis and fermentation, occurs at high initial rates, which can be managed to select for microbes with much higher growth and acetate conversion rates.