Effect of Increasing the Surface Area of the Graphite Electrodes on Electricity Production in a Microbial Fuel Cell (MFC) Fed with Domestic Wastewater

Non-metallic carbon electrodes are widely used in the construction of Microbial Fuel Cells (MFCs) mainly due to their high conductivity and low cost. The objective of this work was to determine the effect of increasing the surface area of the electrodes (with values of R1 = 241 and R2 = 205 cm(2), achieved by making several spherical indentations on them) on the voltage generated in the MFC while treating residual wastewater. The MFC consisted of a chamber provided with four graphite electrodes connected each other by an electric circuit and a resistance of 10 Omega. The device was tested with three different initial organic matter concentrations in the wastewater (389.6, 428.6 and 453.6 mg L-1) and a total process time of 8 days. The voltage generation rates were 0.29 and 0.25 mV.day(-1) (between the 2nd and 5th day) and the maximum values of voltage registered (at 5th day) were 1.9 and 1.5 mV for R1 and R2 respectively. The organic matter removal rates were also dependent of the electrodes surface area; we obtained values of 49.6 mg.L-1/day for R1 and 34.5 mg.L-1/day for R2.