Effects of Flow Velocity on Electricity Production by Sewage Microbial Fuel Cells

摘要

Microbial fuel cells (MFCs) are devices that can recover electricity from sewage biomass, and receive much attention regarding implementation in wastewater treatment. However, the electricity is too low to be used practically. In this study, we focused on the flow velocity of wastewater surrounding an MFC-anode to increase electricity production. The MFC used in this study has a core air chamber surrounded by carbon-cathode, anion exchange membrane and carbon-anode. The MFC was set in an up-flow channel filled with wastewater and polarized at 0 - 20 cm/s of the flow velocity. When the chemical oxygen demand (COD_(cr)) of wastewater was 106 mg/L, the highest electricity was 1.3 times more than that with without flow at 20 cm/s of the flow velocity. While the magnitude increased to 5.5, wastewater had 53 mg/L of COD_(cr) . These results indicate that the flow velocity has a greater effect in sewage wastewater with a lower COD concentration. The relation of the flow velocity, COD_(cr) and electricity were expressed by a Michaeris-Mentene model-based equation and applied to calculate electricity for MFCs of different shapes and layouts. The calculation indicates that the shape and layout of MFCs apparently effects the flow velocity surrounding the MFC and electricity production.