Architecture Optimization of a Single-Chamber Air-Cathode MFC by Increasing the Number of Cathode Electrodes

The aim of this study was the optimization of a single-chamber microbial fuel cell (MFC) architecture, by increasing the number of cathode electrodes. An air cathode single chamber MFC with a modifiable lid and bottom was operated with 4 and 6 Gore-Tex MnO2 cathode electrodes. The anode consisted of graphite granules. It was found that the increase from 4 (total cathodic surface area of 160 cm2) to 6 (total cathodic surface area of 240 cm2) electrodes resulted in an increase of the maximum current and the maximum power output of the cell by approximately 72% and 129%, respectively. Additionally, by increasing the cathodic surface area the internal resistance (Rint) of the unit decreased by approximately 19%. The organic removal from the substrate was not affected by the addition of the new electrodes while it was high across all cases studied (chemical oxygen demand (COD) removal > 89%). The average coulombic efficiency (CE) during the 4-electrode operation was 14.3%, while the corresponding efficiency for 6-electrode operation was 18.5%.