N(2)O emission in a partial nitrification system: dynamic emission characteristics and the ammonium-oxidizing bacteria community.

This study attempts to elucidate the dynamics of nitrous oxide (N(2)O) emission and investigate the evolution of the ammonium-oxidizing bacteria (AOB) community in a partial nitrification system producing an influent suitable for the anammox process. Based on long-term monitoring, (0.80 ± 0.19, n = 7)% of the incoming nitrogen load was emitted as N(2)O. During the partial nitrification process, the N(2)O emission rate reached a maximum at the beginning of the aerobic period and stabilized at a low level after an initial peak. Moreover, the quantity of N(2)O emission increased quickly at the beginning of the cycle operation and then production slowed after 30 min. According to polymerase chain reaction (PCR) and denaturing gradient gel electrophoresis (DGGE) analysis, the dominant AOB causing the N(2)O emission from the partial nitrification system were Nitrosomonas sp. Both Nitrosomonas sp. Nm33 and Nitrosomonas sp. Nm58 were enriched at high ammonia concentrations.