Methanogenic activity and microbial communities characteristics in dry and wet anaerobic digestion sludges from swine manure

The metabolic pathways of methanogenesis in anaerobic digestion sludges were investigated by studying the specific methanogenic activity (SMA) and microbial community structure in dry and we anaerobic digestion sludge (DADS and WADS, respectively). Compared to SMAs in WADS using different substrates, the SMAs in DADS were 15.1% higher (H-2/CO2 as the substrate), 34.5% lower (acetate), 45.5% lower (propionate), 19.5% lower (butyrate) and 5.5% lower (glucose). The genus Petrimonas represented 9.5% and 1.4% of the microbial population in DADS and WADS, respectively. The hydrogenotrophic methanogens Methanocorpusculum (48.0%) and Methanobrevibacter (15.3%) were the dominant archaeal genera in the DADS, and the acetotrophic methanogens Methanosaeta (77.0%) was the dominant archaeal genus in the WADS. This study indicated that anaerobic digestion in DADS possibly was affected by the sensitivity of hydrogenotrophic methanogens to hydrogen partial pressure (P-H2) and the limited mass transfer of hydrogen, which consequently reduced methane production efficiency and altered the metabolic pathway of glucose degradation and methanogenesis.