Efficiency and key functional genera responsible for simultaneous methanation and bioelectricity generation within a continuous stirred microbial electrolysis cell (CSMEC) treating food waste

This study reveals the efficient treatment of high strength food waste under varying hydraulic retention times (48 h, 36 h and 24 h) in a continuous stirred tank reactor (CSTR) integrated with microbial electrolysis cell (MEC) to become a continuous stirred microbial electrolysis cell (CSMEC). COD removal efficiency in the CSMEC surpassed 92% with OLR ranging from 0.4 to 21.31 kg COD/m³·d compared to that of the CSTR. The maximum current density (based on the cathode surface area) was 1125.35 ± 81 mA/m² in the CSMEC. Biogas yield and methane production rates increased by 16.5% and 19.3% in the CSMEC respectively compared to the CSTR. CSMEC was 1.52 times better in performance compared to the CSTR. Firmicutes, Synergistetes, Bacteroidetes, Thermotogae, Chloroflexi and Proteobacteria were the dominant phyla associated with both CSMEC and CSTR. Archaeal microbial community analysis showed Methanosaeta, Methanobacterium, Methanosarcina and Methanocorpusculum as the dominant populations associated with the CSMEC.