Startup performance and microbial communities of a decentralized anaerobic digestion of food waste

The aim of this work was to evaluate the feasibility of treating food waste generated from a hawker centre in a pilot-scale anaerobic digester operating on site in an urban area of Singapore. For this purpose, a 10.4 m3 digester was housed within two 20 feet containerized systems and sited adjacent to the hawker centre. The system reported in this work was during the startup phase, for over 71 days of real and varying food wastes loading rate. The results demonstrated that the decentralized system had an average specific methane yield of 0.55 ± 0.04 m3CH4/kgVS, with methane concentrations of 56.6 ± 2.3%. For the power generation output, the energy assessment revealed an average of 2.05 ± 0.57 m3/kW h consumption rate. Accordingly, on the last day of startup phase, the inoculum of the digester was richer in organisms from the phylum Thermoplasmatota, i.e., genera Candidatus_Methanogranum and Candidatus_Methanoplasma, alongside with other dominant abundance from phyla Bacteroidota, Firmicutes, Synergistota, and Verrucomicrobiota. This study provides new insights into pilot scale decentralized anaerobic digestion with varying food waste relate to the characterizations of digester microbial communities, as well as turning in a typical integrated anaerobic digestion of food waste-to-energy system a reality. [Display omitted] •A decentralized AD of food waste was built and operated reliably in Singapore.•The AD system produced an average of 0.55 m3/CH4 kgVS with 56.6% CH4 content.•Operational state energy balance was recorded 2.05 m3/kW h biogas consumption rate.•Dominant microbial communities were Bacteroidota, Firmicutes and Synergistota.