Microbial community structure of anode electrodes in microbial fuel cells and microbial electrolysis cells

This study investigated the microbial community structure on the anode surface of four dual chamber bio-electrochemical systems. These systems were Microbial Fuel Cell (MFC) and Microbial Electrolysis Cell (MEC). The systems were inoculated with activated sludge and operated for electricity generation/hydrogen (H2) production, and phosphorus (P) recovery. The MFC achieved a maximum power output of 185 mW/m2 (1.62 kW h/m2), whilst the MEC achieved a maximum H2 production rate of 0.28 m3-H2/m3-d. Results from Illumina high-throughput sequencing of 16S rRNA genes showed that the microbial community structure of the MFCs was more diverse than that of the MECs, and this variation may be attributed to the differences in the operational conditions of the MFC and the MEC. MFC and MEC shared the same dominant bacterial phyla; Bacteroidetes, Proteobacteria and Firmicutes, with the most abundant bacterial genus in both systems belonging to Desulfovibrio. However, the abundance of Desulfovibrio in the MECs (13.2 ± 0.7 %) was greater than that in the MFCs (4.25 ± 0.2 %).