[Optimization of the Mainstream Anaerobic Ammonia Oxidation Process and Its Changes of the Microbial Community]

The completely autotrophic ammonium removal over nitrite(CANON)biofilm reactor acclimated by high-strength ammonia wastewater was used to treat low-strength ammonia wastewater. The treatment can be divided into three stages:① the nitrogen removal efficiency of anaerobic ammonia oxidation was low during the continuous aeration stage with inorganic wastewater as raw water (0-59 d) and with an aeration amount of 30 mL·min^-1 and ammonia concentration of 80 mg·L^-1 (until day 56), the TN removal load was only 0.13 kg·(m³·d)^-1; ② during the continuous aeration stage with domestic wastewater as raw water (60-110 d), the addition of organic carbon improved the TN removal load to 0.22 kg·(m³·d)^-1 on day 79; the removal rate of NH₄⁺-N then reached 100% when the aeration volume improved to 100 mL·min^-1 on day 103; however, the TN removal efficiency and TN removal load decreased to 42.36% and 0.14 kg·(m³·d)^-1, respectively. ③ To increase both the NH₄⁺-N and TN removal efficiency during the intermittent aeration stage with domestic wastewater as raw water (110-160 d), the aeration amount was increased to 50 mL·min^-1, while aeration was continued for 30 min and was stopped for the next 30 min; on day 131, the NH₄⁺-N removal efficiency increased to 86.34%, the TN removal efficiency and removal load reached 85.87% and 0.3 kg·(m³·d)^-1 respectively; on day 141, the aeration was increased to 100 mL·min^-1 and the removal efficiency of NH₄⁺-N reached 100%, while the removal efficiency and removal load of TN were 64.28% and 0.22 kg·(m³·d)^-1, respectively, indicating that the intermittent aeration strategy effectively improves the nitrogen removal performance of the CANON reactor. To analyze the variation of the microbial community during different stages, the samples of three stages (0, 56, and 152 d) were analyzed using high-throughput sequencing technology. The results show that:① Candidatus Brocadia is less affected than Candidatus Kuenenia during the low-strength ammonia stages with inorganic and domestic wastewater as raw water; ② Nitrosominas and Nitrospira were the dominant bacteria of AOB(ammonia oxidizing bacteria) and NOB (nitrite oxidizing bacteria), respectively. Domestic wastewater had a greater impact on Nitrosomonas than on Nitrospira; ③ Denitrifying bacteria were present during the whole stage; Pseudomonas and Paracoccus were the most adaptable, even though their relative abundances during each stage were below 0.5%.