Bench-scale decentralized wastewater treatment systems using microbial fuel cell (MFC) techniques were constructed for simultaneous removal of carbonaceous and nitrogenous pollutants and electricity production from wastewater. The MFC was operated in continuous mode and immobilized Paracoccus pantotrophus cells were added in the cathodic compartment to achieve simultaneous nitrification-denitrification. After 150-day operation, the MFC system could effectively remove >96% COD and 100% ammonium, with 60-80% total nitrogen removal and around 0.2 V voltage production. The results of copper (Cu) shock load showed that although 125 mg L-1 Cu (II) would deteriorate the effluent quality and completely inhibit the electricity production, the microbial populations restored their ability to treat wastewater and produce electricity after a period around 30 days. Community analysis by the 454 pyrosequencing technique showed that the microbial compositions were significantly different and decreased in diversity after the Cu shock load. (C) 2013 Elsevier Ltd. All rights reserved.