| The characteristic of nitrous oxide emission during nitrogen removal was studied in a sequencing bio-film CANON reactor with synthetic ammonia-rich wastewater as influent by using haydite as carrier at (30±1) ℃. It was showed that when the initial ammonia was at 200, 300, 400, 500 mg·L-1, the total nitrogen removal efficiency was 84.69%,80.58%,78.16% and 90.09%, respectively, and the total nitrogen removal load was 1.42, 1.48, 1.52, 1.82 kg·(m3·d)-1, respectively，which means the stable nitrogen removal performance of CANON reactor. The corresponding amounts of N2O emissions were 6.44, 10.34, 13.45 and 19.53 mg, respectively, which means that with the increase of initial ammonia concentration, the total amount of N2O release gradually increased. Although the N2O release rate increased, the increase rate of N2O emissions was not very significant, which were 6.06%, 7.00%, 7.06% and 7.15% of total nitrogen removal, respectively. In a reaction cycle, the nitrous oxide and nitrite showed the similar trend of rising first and decreasing next. However, there was no causal link with them. The large amounts of nitrous oxide emission was neither caused by nitrite, nor caused by free nitrous acid, but caused by the accumulation of hydroxylamine. |