pH对高氨氮渗滤液短程生物脱氮反硝化过程动力学的影响

The effect of pH on the kinetics of denitritation in nitrogen removal via nitrite from landfill leachate with high ammonia concentration

为考察实际高氨氮垃圾渗滤液短程生物脱氮过程pH对以NO2--N为电子受体反硝化动力学的影响,本研究采用缺氧/厌氧UASB-SBR生化系统处理实际高氨氮垃圾渗滤液,在SBR系统实现稳定短程生物脱氮(120d运行)的基础上,取SBR反应器内的污泥进行不同NO2--N浓度(5、10、20、40、60、80和100mg·L-1)和恒定pH梯度(6.5、7.0、8.0和8.5)下的反硝化批次试验,基于建立的反硝化动力学方程,确定不同pH条件下以NO2--N为电子受体的反硝化动力学常数.试验结果表明,反硝化菌的还原活性受pH影响较大,pH6.5、7.0和8.5时的最大比反硝化速率(k)分别为pH8.0时的49%、61%和63%;4种pH条件下,NO2--N比反硝化速率与其初始浓度均符合Monod方程,然而不同pH下Monod方程曲线一级反应部分的长短不同,由此导致半饱合常数(Ks)和最大比反硝化速率(k)差异较大,pH8.0下Ks和k最大,分别为15.8mg·L-1和0.435g.g-1.d-1.

The effect of pH on the kinetics of denitritation using nitrite as electron acceptor was investigated in this study. A lab-scale UASB-SBR system was operated to achieve nitrogen removal via nitrite from landfill leachate. Stable nitritation was successfully achieved in the SBR after 120 days. Subsequently,batch tests were carried out to assess the effect of pH on kinetic constants of denitritation using the sludge from SBR at different NO2^--N concentrations （5,10,20,40,60,80 and 100 mg·L^-1） and at different pH gradients （6.5,7.0,8.0 and 8.5）. The pH has a significant inhibitory effect on the activity of denitrifying bacteria. Compared to the maximum specific nitrite reduction rate （k） at pH 8.0,the nitrite reduction rates at pH 6.5,7.0 and 8.5 decreased approximately 49%,61% and 63%,respectively. The relation between the nitrite reduction rate and the initial nitrite concentration followed the Monod-type equation. The length of the first-order portion in the Monod-type curve was distinct,resulting in different Ks and k at pH 6.5,7.0,8.0 and 8.5. The highest Ks and k at pH 8.0 were calculated to be 15.8 mg·L^-1and 0.435 g·g^-1·d^-1,respectively.