Optimizing the electrode surface area of sediment microbial fuel cells.

Sediment microbial fuel cells (SMFCs) is a promising technology for bioremediation, environmental monitoring and remote power supply in various water environments. Optimizing the anode/cathode surface area ratio (SAR) is important to enhance the power and decrease the cost of SMFCs. However, in fact, little information has been reported to optimize the SAR of SMFCs in individual or stacked mode. This study comparatively analyzed the effects of electrode surface areas on the performance of single SMFCs and serial SMFC-stacks under separated- and connected-hydraulic conditions. The results suggested an optimal SAR of 1 to 1.33 for both single and serial stacked SMFCs. Voltage reversal occurred in serial SMFC stacks with unoptimal SAR but not in optimized stacks. The more the SAR deviated from the optimal SAR, the more easily the voltage reversal occurred ( lower reversal current). Compared to a separated-hydraulic environment, a connected-hydraulic environment showed no effect on the power generation of anode-limiting SMFC stacks but decreased the power generation and reversal current of cathode-limiting SMFCs, probably due to larger parasitic current. The results are important for the scale-up and application of SMFCs.