游离氨对城市生活垃圾渗滤液短程硝化的影响

Effect of Free Ammonia on the Short-Cut Nitrification of the Municipal Landfill Leachate

为了考察游离氨（free ammonia,FA）对高氮城市生活垃圾渗滤液短程硝化的影响,采用＂两级UASB-缺氧-好氧系统＂处理实际城市生活垃圾渗滤液.首先在UASB1中实现同时反硝化与产甲烷反应,COD在UASB2中进一步去除,在A/O反应器中利用残余COD进行反硝化以及将NH4^＋-N彻底硝化.试验共进行79 d,经历3个阶段,即稳定短程硝化（40 d）、短程硝化破坏（19d）、短程硝化恢复（20 d）.结果表明,适当的游离氨浓度（40--70 mg.L^-1）可实现稳定的短程硝化,如在阶段1中亚硝态氮积累率为97%,氨氮的去除率为99%.但游离氨浓度在160 mg.L^-1左右会抑制全部的硝化反应.在阶段3中,通过稀释原水降低了游离氨浓度,在短时间内就恢复了短程硝化.可见,游离氨是实现和维持城市生活垃圾渗滤液短程硝化的重要影响因素.

A system consisting of a two-stage UASB and anoxic-oxic reactor was used to study the influence of FA on short-cut nitrification of the actual municipal landfill leachate with high ammonia concentration. In the UASB1, denitrification and methanogenesis took place simultaneously. The effluent COD of UASB1 was further removed in the UASB2. Then the denitrification of nitrite and nitrate in the returned sludge by using the residual COD and nitrification was finished in the A/O reactor. The experiment experienced three stages during 79 d. The stable short-cut nitrification was achieved in the first stage （40 d）. The short-cut nitrification was damaged in the second stage （19 d）, and the short-cut nitrification was recovered in the last stage （20 d）. The results of 79 d showed that when the FA concentration was about 40-70 mg.L^-1, the stable short-cut nitrification could be achieved. For example, the nitrite accumulation was 97 % in the system during the first stage, and the ammonia removal efficiency was 99% . But when the FA concentration was about 160 mg.L^-1 , the nitrification would be inhibited. In the third stage, raw leachate was diluted by tap water in order to decrease the FA concentration. And then the short-cut nitrification was recovered soon. In a word, the FA concentration is an important factor to achieve the short-cut nitrification of the municipal landfill leachate.