Evaluation of electromethanogenesis in a microbial electrolysis cell using nylon cloth as a separator: Reactor performance and metagenomic analysis

Abstract

This study aimed to propose a novel approach for simultaneous CO2 abatement and energy storage in microbial electrolysis cells (MECs). The methane (CH4) production from CO2 was achieved in a graphite granule–filled cathodic compartment of an MEC separated by a modified nylon cloth. Using the modified nylon cloth in MEC significantly reduced membrane internal resistance compared with the control where a commercial proton exchange membrane (PEM) was used (PEM: 1746 ± 80 TΩ/cm; nylon cloth: 251 ± 8 TΩ/cm). Consequently, CH4 production realized 72.9 ± 24.4 mL/(L ∙ d) with an average energy efficiency of 121 ± 39% compared with halted electromethanogenesis in PEM-equipped MEC. Metagenomics affirmed the predominance of hydrogenotrophic methanogens Methanocorpusculum and Methanobacterium. Moreover, H2-mediated methanogenesis contributed significantly to electromethanogenesis in nylon-MEC. This study demonstrated that the bioelectrochemical conversion of CO2 into CH4 in a nylon-MEC could be viable for CO2 sequestration combined with energy storage (power to gas).