氨氮负荷对膜曝气生物膜反应器部分亚硝化性能的影响

Effect of ammonium loading on partial nitritation in membrane-aerated biofilm reactor for treating ammonium-rich wastewater

对不同进水氨氮负荷下中试膜曝气生物膜反应器（MABR）部分亚硝化性能进行了考察,旨在确定在MABR中启动、优化和维持稳定亚硝化的控制策略.在进水氨氮表面负荷由（4.9＆#177;0.4）g·m-2·d-1（以N计,下同）升至（9.1＆#177;0.5）g·m-·2d-1的过程中,MABR氨氮去除负荷可以达到（5.7＆#177;0.5）g·m-2·d-1.当进水氨氮负荷为7.4 g·m-2·d-1时,本试验MABR部分亚硝化效果最佳,亚硝化率可达96.3％.部分亚硝化的维持需要控制合适的生物膜厚度,当生物膜厚度在110- 170 μm之间时,MABR亚硝化率在90％左右,能够有效实现对亚硝酸盐氧化菌（NOB）的抑制和亚硝酸盐的积累.利用微生物比氧利用率（SOURAOB）来反映生物膜中氨氧化菌（AOB）的活性,发现MABR生物膜的SOURAOB可达（133.9＆#177;31.1） mg·g-1·h-1（以每g SS利用的O2量（mg）计）.实时定量PCR结果也表明AOB为MABR生物膜中的优势菌群,其微生物丰度比接种污泥高出3个数量级.通过调控进水氨氮负荷和生物膜厚度,维持AOB的种群优势和高活性并同时抑制NOB的活性,可以实现MABR的稳定部分亚硝化.

A pilot-scale membrane-aerated biofilm reactor （MABR） was operated via incrementally increasing influent NH-N loading rates, from （4.9± 0.4 ） g·m-2·d-1 （ the same below） to （ 9.1 ± 0.5 ） g·m-2·d-1. The goal of the study was to develop an operational strategy for establishing, optimizing and maintaining a stable partial nitritation in the reactor. When the influent NH4-N surface loading rate was increased to （9.1 ±0.5 ）g·m-2·d-1, NH4-N removal rate reached （5.7±0.5） g·m-2·d-1. When the influent NH4-N loading rate was maintained at 7.4 g·m-2·d-1, the nitritation efficiency in the MABR reached the maximum of 96.3%. Maintaining a stable partial nitritation required controlling biofilm thickness. When biofilm thickness was maintained between 110 ± 170 μm, the nitritation rate was stable at about 90% and specific oxygen uptake rate （ SOURAoB ） , representing the activity of ammonia oxidizing bacteria （AOB）, reached maximum of （133.9±31.1） mg（ 02 ）-g （SS）-l·h-l. The results of real time quantitative PCR showed that AOB dominated the microbial population in the biofilm, as expected, and their abundance was 3 orders of magnitude higher than that in the sludge used to inoculate the reactor. In conclusion, maintaining a stable partial nitritation requires controlling two factors ： the influent NH4-N loading rate and the biofilm thickness. When these factors are properly controlled, AOB dominate the microbial population in the biofilm and the activity of nitrite oxidizing bacteria （NOB） is inhibited, thus resulting in partial nitritation.