气水比对曝气生物滤池N2 O产生的影响

摘要

针对目前有关曝气生物滤池中N2 O产生与控制问题研究较少的现状,以城市污水为研究对象,利用曝气生物滤池,重点研究了气水比为9.8：1、5.0：1和2.5：1的条件下,曝气生物滤池中N2 O的产生与转化情况.试验结果表明：BAF工艺中NH4+-N和TN的去除率均随气水比的减小而减小；气水比为9.8：1、5.0：1和2.5：1的条件下, N2 O的释放量在空气中的百分比分别为418.0306×10-6、247.9406×10-6和123.0638×10-6,因此,BAF中N2 O的产生不容忽视.在不同的气水比条件下,溶解态N2 O-N的沿程变化规律均为先增加后减小,且溶解态N2 O-N质量浓度与NO2--N质量浓度沿程变化规律一致,据此推测,N2 O可能产生于硝化反应过程.综合考虑硝化效果、TN去除效果以及N2 O减排控制,确定本试验条件下的BAF中适宜控制的气水比为5.0：1.%Biological aerated filter ( BAF) has been widely used in treatment of wastewater and reclaimed water. To date, little research has been done to control N2 O production in BAF. N2 O production from municipal wastewater at different air-water ratio of 9. 8:1 ,5. 0:1 ,2. 5:1 respectively was investigated in biological aerated filter ( BAF ) . The obtained results show that NH4+-N and TN removal efficiency decreases with the decrease of air-water ratio. Under the condition of air-water ratio of 9. 8:1,5. 0:1, 2. 5:1, the percent of N2 O emission from BAF was 418. 030 6, 247. 940 6, 123. 063 8 í 10 -6 , respectively, indicating that N2 O production in BAF can not be ignored. N2 O-N dissolved in the mixture at different air-water ratio increased first and then decreased along the filter layer, which was consistent with the variation of NO2--N concentration. Therefore, N2 O might be produced during nitrification. Considering nitrification efficiency, TN removal efficiency and N2 O emission control, the optimal air-water ratio is 5. 0:1 .