A bioelectrochemical system (BES) containing membrane-aerated nitritation-anammox in its cathode has been developed for enhancing nitrogen removal. Long-term performance and microbial community structure were investigated. The BES using loop operation and external voltage achieved the highest total nitrogen removal efficiency of 94.8 +/- 7.7%, and COD removal of 98.2 +/- 3.3% at hydraulic retention time of 60 h and the lumen pressure of 10 psi. The energy consumption of the system was 0.90 kWh kg N (1) or 0.38 kWh kg COD (1). Sequencing analyses revealed that ammonia oxidizing bacteria (0.2-7.4%), anammox bacteria (0.4-10.3%), denitrifying bacteria (5.8-13.1%), and electrogenic bacteria (4.6-12.8%) were in abundance of the microbial community in the cathode chamber, and their distributions were affected by the aeration and physical locations. These results encourage further investigation of membrane-aerated nitritation-anammox in BES for optimization and potential applications with actual wastewater. (C) 2017 Elsevier Ltd. All rights reserved.