[Performance of the Removal of Nitrogen During Anaerobic Ammonia Oxidation Using Different Operational Strategies]

The effects of low substrate ratio, cooling methods, and pH on nitrogen removal performance were studied in a laboratory-scale anaerobic ammonium oxidation reactor (ASBR) while treating simulated domestic waste water. The results illustrated that the average removal efficiencies of NH₄⁺-N and NO₂^--N increased from 54.4% and 65.3% to 95.8% and 92.5%, respectively, at a temperature of 30℃ and an influent concentration of NO₂^--N of (30±0.2)mg·L^-1. The substrate ratio (NO₂^--N/NH₄⁺-N) increased from 0.9 to 1.4.However, the removal efficiency of NH₄⁺-N was affected negligibly, and the average removal efficiency of NO₂^--N decreased to 54.6% when the substrate ratio was increased to 1.6, suggesting that the nitrogen removal performance of anaerobic ammonium oxidation was best when the substrate ratio was close to the theoretical value of 1.32.The average removal efficiencies of NH₄⁺-N and NO₂^--N decreased from 97.5% and 98.5% to 35.2% and 40.1%, respectively, when the temperature of the reactor dropped from 30℃ to 15℃ at one time. The average removal efficiencies of NH₄⁺-N and NO₂^--N dropped from 97.7% and 98.6% to 52.7% and 62.4%, respectively, when the ladder cooling method(30℃→25℃→20℃→15℃) was used. The average removal efficiencies of NH₄⁺-N and NO₂^--N increased initially and then decreased when the pH was increased gradually from 7.7 to 8.5.The highest nitrogen removal efficiency was achieved when the pH was controlled at 8.3 with a substrate ratio of NO₂^--N/NH₄⁺-N equal to 1.4.