This study has served as more encouraging signs that constructed wetlands (CWs) can incorporate microbial fuel cells (MFCs) into their design to produce electrical energy while treating wastewater. Two 3.7 L CW-MFCs have been constructed to treat swine wastewater with one (System 1) operated in batch mode while the other (System 2) was operated in continuous, upward flow mode and incorporated air diffusion heads to aerate the cathode. System 1 removed, on average, 71.5% of COD (with initial concentration of 3190-7080 mg/L) and produced a peak power density of 12.83 mu W/m(2). The aeration of the cathode significantly enhanced the performance of the CW-MFC, with System 2 demonstrating an average of 76.5% COD removal (average influent COD concentration of 1058.45 +/- 420.89 mg/L) with a peak power density of 9.4 mW/m(2). (C) 2013 Elsevier B.V. All rights reserved.