A surface floating, air cathode, microbial fuel cell (MFC) with a horizontal flow is devised and characterized using glucose-based synthetic wastewater. The performance of the MFC is significantly affected by the current-collector of the electrodes. When graphite foil ribbon (150 cm) serves as the current-collector, the respective specific internal resistance and maximum power density are 0.362 Omega m(-2) and 124.0 W m(-3). The internal resistance can be reduced by increasing the length of the current-collector. For a graphite ribbon current-collector 256 cm long, the specific internal resistance is only 0.187 Omega m(-2) and the maximum power density markedly increases to 253.6 W m(-3); however, the maximum power density is affected by the current-collector material. When the current-collector is changed to a stainless-steel wire, the maximum power density is reduced to approximately 100 W m(-3) because of its high liquid vertical bar solid interfacial impedance. During three continuous months of operation, issues such as leaking are not observed and as such, the MFC could be easily scaled-up for wastewater treatment by increasing the electrode size and stacking a number of cells without additional ohmic resistance. (C) 2010 Elsevier B.V. All rights reserved.