Bioelectrical power generation from ethanol stillage wastewater digestion was studied in a 4 L two-compartment microbial fuel cell ( MFC) using Nafion 117 as a proton exchange membrane (PEM). The results showed that the most promising configuration of the MFC was using of two anodes with the anode-to-cathode surface area ratio of 1:2.2 located at the nearest distance between cathode and anodes at the external resistance of 560 Omega. This optimum configuration achieved the highest power density of 93W/m(an)(2) with 81.5% chemical oxygen demand (COD) removal after 6 days of operation when 0.1 mol/L lignin was added as mediator. (c) 2012 Elsevier Ltd. All rights reserved.