Improved performance of a tubular microbial fuel cell with a composite anode of graphite fiber brush and graphite granules

In this study, a composite electrode combined of a graphite fiber brush and carbon granules (MFC-GFB/GG) was adopted as the anode of a tubular microbial fuel cell (MFC). Compared with an MFC with graphite granules (MFC-GG) and an MFC with a graphite fiber brush (MFC-GFB), MFC-GFB/GG showed a longer lag time during the start-up process, while it reached the highest operating voltage at 50 Ω. Furthermore, during the stable operation, the MFC-GFB/GG achieved the highest power density of 66.9 ± 1.6 W m−3, which was about 5.3 and 1.2 times as that of MFC-GG and MFC-GFB, respectively. The highest performance of the MFC-GFB/GG can be attributed to the highest active biomass content on the electrode and the smallest internal resistance of the MFC. The optimum COD concentration was found to be 500 mg COD L−1 for MFC-GFB/GG.