Anaerobic co-digestion of organic fractions of municipal solid waste: Synergy study of methane production and microbial community

Abstract

The anaerobic digestion (AD) of organic fractions of municipal solid waste (OFMSWs) represents a promising solution for achieving greater landfill diversion and resource recycling. The objectives of this study were (1) to explore potential synergistic effects on methane production of co-digestion of organic MSW components with distinct levels of biodegradability and (2) to examine whether and how the inoculum source affect those synergistic effects on methane yields and kinetics. Anaerobic mono- and co-digestion of food waste (FW), newsprint paper (NP), and branches (BR) were conducted in a batch culture system inoculated with landfill leachate and anaerobic sludge under mesophilic conditions. The methane generation results showed that co-digestion of readily degradable FW with more recalcitrant lignocellulosic NP and/or BR resulted in additive effects on cumulative yield but synergistic effects on production rates (up to 22% yield increase between 10 and 15 days). This early synergism was primarily associated with the accelerated hydrolysis due to the addition of FW that promoted the growth of hydrolytic microorganisms. A 16S rRNA sequencing-based community analysis revealed that the microbial communities were primarily influenced by their inoculum and cannot explain for the observed synergy. These results suggest that when multi-component municipal waste is used as AD feedstock, the early synergistic benefits can be considered for process design and optimization.