Interactions among the components of artificial biomass during their anaerobic digestion with and without sewage sludge

Anaerobic digestion (AD) of artificial biomass (composed of cellulose, hemicellulose, lignin) with or without sludge was conducted, focusing on the interaction among the components of biomass and sludge. The results showed that lignin inhibited the anaerobic degradation of cellulose, hemicellulose, and sludge, the interaction between cellulose, hemicellulose, and sludge promoted the formation of methane. As for AD of artificial biomass, the cumulative methane yield (CMY) from co-digestion of cellulose and hemicellulose was 299.85 mL/g VSadded, with the highest synergistic index of 1.36 among runs of AD of two-component-mixture artificial biomass. The bacterial community was rich in Lachnospiraceae for co-digestion of cellulose with hemicellulose, while it was rich in Ruminococcacea and Clostridiaceae for mono-digestion of cellulose, hemicellulose respectively. As for AD of artificial biomass with sludge, synergistic effect on CMY was observed in most runs. The dominant VFA was changed to acetic acid at the early stage of the AD process at the presence of sludge. The diversity and evenness of the bacterial community were greatly improved with the addition of sludge, enlarging the amount of meth-anogenic Methanobrevibacter for promoting CMY. The digestion performance and methane production were improved as the F/B ratio was decreased with addition of sludge.

Automated summary

This study investigated the anaerobic digestion of artificial biomass and sludge and found that lignin inhibited the degradation of cellulose, hemicellulose, and sludge, while the interaction between cellulose, hemicellulose, and sludge promoted methane production. The addition of sludge improved the diversity and evenness of the bacterial community, leading to increased methane production.