Abstract: In recirculating aquaculture system(RAS), the metabolites and residual feed of fish are the main sources of ammonia nitrogen.The biological filter is widely used to avoid the accumulation of ammonia nitrogen.Autotrophic nitrification plays an important role in biological filter.However, the proliferation period of autotrophic nitrification is relatively long, and susceptible to temperature; once the system fails to run, it takes a long time for nitrifying bacterial colony to recovery.In recent years, electrochemical oxidation technology has been applied to remove ammonia nitrogen.In this paper, the removal rates of ammonia nitrogen under different flow velocities, temperatures and current densities were investigated.The artificial wastewater with added ammonia nitrogen was used in this study.The salinity of wastewater was 30‰, and the initial concentration of ammonia nitrogen was 10 mg/L.The micro-current electrolysis system was placed in a climatic cabinet to obtain a desirable temperature.The prepared wastewater of 2 L was poured into a beaker and heated by a constant temperature magnetic stirrer.The wastewater was circulated between electrolysis cell and beaker using a peristaltic pump, and then the power supply was enabled 10 min later.Various values of flow velocity(100, 300 and 500 mL/min), temperature (18, 25 and 32 ℃) and current density(20, 40 and 60 A/m2) were used in the experiments, and the ammonia nitrogen concentration was measured every 15 min.Moreover, the optimal electrolytic condition was established by the orthogonal analysis.The energy consumption of removing ammonia nitrogen was also calculated.The results showed that the removal rates of ammonia nitrogen after 90 min with different flow velocity of 100, 300 and 500 mL/min reached 92.38%, 95.15% and 93.27% respectively under the condition of 25 ℃ and 40 A/m2.Single factor analysis showed that the flow velocity had no significant effect on the removal rate.When the current density was 40 A/m2, the flow velocity was 300 mL/min, the removal rates of ammonia nitrogen reached 87.45%, 88.78% and 92.25% respectively after 60 min with different temperature of 18, 25 and 32 ℃.Single factor analysis showed that the temperature had no significant effect on the removal rate.When the temperature was 25 ℃, the flow velocity was 300 mL/min, the removal rates of ammonia nitrogen reached 59.32%, 87.89% and 89.01% respectively after 60 min with different current density of 20, 40 and 60 A/m2.Single factor analysis showed that the current density had significant effect on the removal rate, and the removal rate of ammonia nitrogen increased with the current density.The orthogonal analysis showed that the current density was the main influence factor of ammonia removal rate, and the optimum conditions were the current density of 40 A/m2 and the flow rate of 300 mL/min, which resulted in the lowest energy consumption of 21.26 Wh/kg.Therefore, the micro-current electrolysis technology has good effect on the removal of ammonia nitrogen, the removal efficiency is relatively higher, and the energy consumption is relatively lower.The micro-current electrolysis technology has a great potential for application compared with the traditional biological filter.