BACKGROUNDDeveloping an economical biological nitrogen and phosphorus removal technology with high efficiency has become a research priority in current sewage treatment procedures. In order to solve the problems within the anaerobic-anoxic-oxic (A(2)/O) process, including substrates competition and high energy consumption, a microbial fuel cell (MFC) was embedded in the A(2)/O process to enhance the efficiencies of removal of nitrogen and phosphorus, along with electricity production. RESULTSThree A(2)/O reactors, one with an embedded MFC, were set up, and nitrogen and phosphorus removal efficiencies and electricity generation were investigated. At the stage of stable operation, the chemical oxygen demand, total nitrogen and total phosphorus removal efficiencies of the MFC-A(2)/O reactor, compared with the control, were increased by 15.9%, 9.3% and 1.4% on average, respectively. The average output power density of the MFC was 14.31.4 mW m(-3) and the internal resistance was 6000 . Grey relational analysis was applied to study the most significant operational parameter of the A(2)/O process affecting electricity production of the MFC. CONCLUSIONS

This research proved that nitrogen and phosphorus removal efficiency could be improved by embedding an MFC in the A(2)/O process. In addition, the MFC-A(2)/O reactor can generate electricity continuously. (c) 2013 Society of Chemical Industry