Objective To construct the dual microbial fuel cell (DMFC) by coupling anaerobic ammonia oxidation sludge and chlorella, hoping to remove the high concentration of nitrogen, phosphorus and organic matter in aquaculture wastewater while generating electricity, and provide a new way for aquaculture wastewater disposal and bioenergy preparation.

Method The anaerobic ammonia oxidation sludge was mixed with simulated wastewater at the volume ratio of 1∶4 and added to the anode chamber, while chlorella was mixed with BG-11 medium at the volume ratio of 1∶4 and added to the cathode chamber. After running for 24 h, the anode chamber began to discharge water, which was then added to the cathode chamber. The system was maintained at a constant temperature and a light-dark cycle mode. The voltage, mass concentrations of ammonia nitrogen/NO₂⁻-N/NO₃⁻-N/total phosphorus, soluble chemical oxygen demand (SCOD) and pH of wastewater were monitored during the system running.

Result There was an obvious electron exchange between the anaerobic ammonia oxidation sludge and chlorella, and the system had good electric generation performance, the positive and negative peak voltages of DMFC in the stable operation stage were 45 and −125 mV respectively. The ammonia nitrogen mass concentration decreased from 1 588.97 mg/L to 602.75 mg/L, with the removal rate of 62.07%; The removal rates of NO₂⁻-N, total phosphorus and SCOD were 88.62%, 54.45% and 63.72% respectively. The system operated stably at pH 9.5.

Conclusion This study successfully establishes a DMFC system constructed by coupling anaerobic ammonia oxidation sludge and chlorella. The system not only effectively removes nitrogen, phosphorus and reduces organic matter concentration but also continuously generates electricity, providing an effective way to address environmental and energy issues simultaneously.