Enhancement of power generation with concomitant removal of toluene from artificial groundwater using a mini microbial fuel cell with a packed-composite anode

Composite beads are packed in the anode chamber of a microbial fuel cell (MFC), providing more area for microbial attachment and growth, increasing the efficiency of removal of toluene from toluene-contaminated groundwater. The composite beads were fabricated by integrating carbon coke (CC) with a relatively large specific surface area to which microorganisms easily adhere with conductive carbon black (CCB), which has low electrical resistance. Since the advantages of both are complementary, the power generation of MFC is improved. The single layer-packed anode MFC (SP-MFC) completely degraded 200 mg L^-1 of toluene - 2.3 times faster than the non-packed anode MFC (NP-MFC). The high power density (44.9 mW m^-3) and oxidation peak (1 mA), with low internal resistance (207 Ω) revealed that SP effectively improved the power generation efficiency. A composition ratio (CR_CCB:CC) of composite beads of one to two yielded the best performance with a removal efficiency of 100 % - 76 % faster than CC. The closed circuit voltage of CR_1:2 MFC reached 340 mV, which was 16 times that of CC; the power density and oxidation peak reached 103 mW m^-3 and 1.38 mA, respectively. Therefore, CR_1:2 effectively increased the overall removal efficiency and power generation of the MFC.