Effect of pH and distance between electrodes on the performance of a sediment microbial fuel cell.

The performance of three sediment microbial fuel cells (SMFCs) was evaluated at different feed water pH and electrode spacing for chemical oxygen demand (COD) removal, total nitrogen (TN) removal, and power density; while offering in situ remediation of aquaculture pond water. SMFC-A was operated at the feed water pH of 6.5 and spacing between the electrodes of 100 cm. SMFC-B and SMFC-C were operated at feed water pHs of 8.5 and 6.5, respectively, and distance between electrodes of 50 cm. The anode and cathode were connected with concealed copper wire through an external load of 100 Ω. The average amount of total COD removal rate and TN removal rate, per unit area of cathode, were 1.72 ± 0.06 and 0.021 ± 0.007 g/m(2) d in SMFC-A, 1.03 ± 0.08 and 0.024 ± 0.005 g/m(2) d in SMFC-B, and 1.14 ± 0.01 and 0.017 ± 0.001 g/m(2) d in SMFC-C, respectively. SMFC-A, operated with higher distance between electrodes, demonstrated better removal of organic matter and highest open circuit voltage of 0.903 V. SMFCs with less feed pH (6.5) gave higher COD removal and feed pH of 8.5 gave higher TN removal. SMFCs operated with lesser distance between electrodes gave higher power density.