The performance of a dual anode-chambered microbial fuel cell (MFC) inoculated with Shewanella onesdesis MR-1 was evaluated This reactor was constructed by incorporating two anode chambers flanking a shared air cathode chamber in an electrically parallel geometrically stacked an angement The de vice was shown to have the same maximum power density (approximately 24 W m(-3) normalized by the anode volume) as a single anode- single cathode-chambered MFC The dual anode-chambered unit generated a maximum current of 3 66 mA (at 50 Omega) twice the value of 1 69 mA (at 100 Omega) for the single anode-chambered device at approximately the same volumetric current density Increasing the Pt-coated cathode surface area by 100% (12 to 24 cm(2)) had no significant effect on the power generation 01 the dual anode-chambered MFC indicating that the performance of the device was limited by the anode The medium recirculation rate and substrate concentration in the anode were varied to determine their effect on the anode-limited power density At the highest recirculation rate 5 ml min(-1) the power density was about 25% higher than at the lowest recirculation rate 1 ml min-1 The dependence of the power density on the lactate concentration showed saturation kinetics with a half-saturation constant K, on the order of 4 4 mM (c) 2010 Elsevier BV All rights reserved