高氨氮废水短程硝化过程中N2O释放试验研究

试验采用序批式反应器(SBR)处理高氨氮废水,逐步提高废水氨氮(NH+4-N)浓度到800 mg·L-1,通过控制曝气量实现了短程硝化.SBR周期试验表明,在低溶解氧和高游离氨等共同作用下,氨氧化菌(AOB)活性较低,导致AOB以亚硝酸盐氮(NO_2~--N)作为电子受体进行好氧反硝化,氧化亚氮(N_2O)释放因子为9.8%.静态试验控制初始NH_4~+-N为100 mg·L-1且改变曝气量(0.22~0.88 L·min~(-1))条件下,溶解氧浓度的增加能够提高硝化菌活性,N2O释放因子为0.51%~0.85%.当初始NH_4~+-N浓度为100 mg·L~(-1)且曝气量控制在0.66 L·min-1时,初始NO-2-N浓度为0~100 mg·L~(-1)对硝化菌活性影响较小,N2O释放因子为0.50%~0.71%.当溶解氧和游离氨浓度控制在适宜范围内,可维持AOB较高活性,抑制AOB发生好氧反硝化作用,降低N2O释放率.

N2O emission during short-cut nitrification of high ammonium containing wastewater

By controlling the aeration rate in a sequencing batch reactor (SBR), nitritation was achieved with the influent ammonium nitrogen (NH₄⁺-N) concentration gradually increased to 800 mg·L^-1. Within the typical SBR reaction cycle, factors such as low dissolved oxygen and high free ammonia concentrations caused low activity of ammonia oxidation bacteria (AOB), and nitrifiers denitrification was carried out by AOB with nitrite nitrogen (NO₂^--N) as the electron acceptor and the emission factor of nitrous oxide (N₂O) was 9.8%. During batch experiments, with the initial NH₄⁺-N concentration of 100 mg·L^-1 and varied aeration rates (0.22~0.88 L·min^-1), nitrifier activities increased with increasing dissolved oxygen concentrations and the N₂O emission factor was in the range of 0.51%~0.85%. With the initial NH₄⁺-N concentration of 100 mg·L^-1 and the aeration rate of 0.66 L·min^-1, the applied NO₂^--N concentration of 0~100 mg·L^-1 affected little on nitrifier activities and the N₂O emission factor was in the range of 0.50%~0.71%. By controlling suitable dissolved oxygen and free ammonia concentrations, high activity of AOB could be maintained, resulting in the inhibited aerobic nitrifier denitrification and the reduced N₂O emission.