Faeces and food waste co-digestion for development of decentralised urban resource recovery in Singapore

As the core technology of decentralised urban resource recovery system, the objective of this study was to evaluate the feasibility of anaerobic co-digestion of faeces (brown-water, BW) and foodwaste (FW). Batch assay indicated that anaerobic co-digestion (BW+FW) showed higher methane yield (0.540.59 LCH4/gVSadded) than BW and FW alone. Anaerobic co-digestion was subsequently performed in a mesophilic (33C) semi-continuously fed laboratory-scale two-phase CSTR reactors. No obvious lag phase was observed in the start-up period. During the 120-days of operation, CODs, CODt, VS removals were ranged of 75.993.4%, 51.969.6% and 63.469.4%, respectively, with methane yield of approximate 0.4 LCH4/gVS under 1620 days HRT conditions. Microbial analyses suggested that Lactobacillus and Acetobacter were important for initial degradation of BW+FW in the acidogenic reactor, while a complex bacterial populations and methanogens (Methanosaeta and Methanosarcina) were found in the methanogenic reactor. The overall positive findings show the great potential of applying anaerobic co-digestion of BW+FW for energy production and waste management. Decentralized, source-separation, and anaerobic co-digestion of BW+FW is expected to provide a practical solution for those countries experiencing rapid urbanization and water shortage issues, such as Singapore.