Integrating microbial electrochemical cell in anaerobic digestion of vegetable wastes to enhance biogas production

Abstract

Anaerobic digestion is a highly promising approach to manage agricultural/food wastes that reduces pollution and produces energy effectively. In this study, we investigate the incorporation of a microbial electrolysis cell (MEC) in anaerobic digestion process with the introduction of two graphite felts to enhance biogas production with minimal electrical energy input. The high amount of biogas (1890 ± 113.1 mL) was produced from the 1:2 v/v mixture of vegetable wastes in water and 0.8 V supplemented at 27 °C. Biogas could also be effectively produced in MEC at 18 °C (632 ± 14.8 mL), which is more than double in comparison with biogas produced without voltage (303 ± 27.5 mL). Maximum COD reduction was found in MEC (70.84 ± 5.54 %) than in control (20.35 ± 4.53 %). Three Bacillus strains and one Exiguobacterium strain were isolated from the MEC sludge. Electricity supplemented anaerobic digestion can produce higher amount of biogas and improve waste degradation by transforming waste into energy.