Anaerobic Co-Digestion of Organic Fractions of Municipal Solid Waste: Synergy Study on Methane Production and Microbial Community

Abstract

Anaerobic digestion of organic fractions of municipal solid waste (OFMSWs) represents a promising solution to achieve greater landfill diversion and resource recycling. The objectives of this study were (a) to explore potential synergistic effects on methane production in co-digestion of organic MSW components with distinct biodegradabilities, and (b) to evaluate whether and how the inoculum source and substrate composition affected methane production and microbial community composition. Anaerobic mono- and co-digestion of food waste (FW), newspaper (NP) and branch (BR) were conducted in a batch culture system inoculated with landfill leachate (LL) and anaerobic sludge (AS) under mesophilic conditions. The 16S rRNA sequencing based community analysis revealed that the microbial communities consisted of taxonomically diverse but methane yielding populations, and were primarily influenced by their inoculum. The methane generation results showed that co-digestion of readily degradable FW with more recalcitrant lignocellulosic NP and/or BR, only resulted in additive effects on the cumulative yields, but synergistic effects on the production rates (up to 22% yield increase between 10 to 15 days). This early synergism was primarily associated with the accelerated hydrolysis due to the FW addition to promote the growth of hydrolysis microorganisms. These results suggest that multi-component feedstock (e.g., OFMSWs) is preferred for efficient AD systems and brings in early synergism benefits for process optimization in practice.