常温下接种回流污泥实现BAF一体化自养脱氮工艺

为实现高氨氮废水的高效低耗稳定去除，在常温条件下，对曝气生物滤池（BAF）中实现与稳定短程硝化-厌氧氨氧化自养脱氮工艺进行了研究。研究结果表明：常温条件下，BAF接种二沉池回流污泥，采用闷曝-连续运行结合的接种挂膜方式，可成功实现短程硝化-厌氧氨氧化一体化自养脱氮。闷曝阶段使种泥活性恢复，而连续流运行过程中游离氨（FA）浓度高，可抑制亚硝酸盐氧化菌（NOB），实现BAF中亚硝酸盐累积；通过调整BAF回流方式，降低回流液中NO₂^--N，防止NOB生长，并通过厌氧氨氧化（Anammox）滤池出水回流方式，接种微量Anammox菌，运行80 d可实现短程硝化-厌氧氨氧化，140 d后系统运行稳定，总氮（TN）去除率达76.62%。生物滤池有利于短程硝化-厌氧氨氧化工艺的实现与稳定，生物膜中不同厚度存在好氧缺氧环境，利于氨氧化菌（AOB）和Anammox菌共存；滤料的过滤作用有效地防止了Anammox菌流失，使其在系统中不断累积生长。不仅如此，AOB和Anammox菌均为自养菌且生长缓慢，避免了生物滤池的频繁反冲洗，简化了生物滤池的运行。气水比是BAF中一体化运行的关键参数，本研究中最佳的气水比为12：1，氨氮去除负荷达到0.91 kg N·m^-3·d^-1，氨氮和TN去除率分别可达96.86%和85.47%。

Implementation of integrated autotrophic nitrogen removal system at normal temperature by returned sludge

To treat high ammonia nitrogen wastewater efficiently and low costly, achieving and stabilizing autotrophic nitrogen removal in biology aerated filter (BAF) were studied. The obtained results showed that autotrophic nitrogen removal was achieved through the combination of batch and continuous operation in the BAF with volcanics as filter, using the second pond reflux sludge as seeding sludge. During batch operation, the activity of seeding sludge was recovered. During the continuous operation, high free ammonia (FA) concentration inhibited the growth of nitrite oxidation bacteria (NOB). Through recycling the effluent of anaerobic ammonia oxidation (Anammox) biofilter, very slight of Anammox bacteria was inoculated in BAF. After 80 days operation, autotrophic nitrogen removal was achieved. From the 140th day, the removal rate of total nitrogen (TN) approach to 76.62%, and it can be stable all the time. Since aerobic and anoxic environment occurred in different depth of biofilm, ammonia oxidation bacteria (AOB) and Anammox bacteria can coexist in biofilm. Meanwhile, the filtration of volcanics can prevent Anammox bacteria from flowing out of BAF, making the enrichment of Anammox in the system of autotrophic nitrogen removal. In the meantime, AOB and Anammox as autotrophic bacteria grows slow, preventing the biofilter backwash frequently and simplifying the operation of biofilter. Air and water ratio is one of the key operation parameters in BAF of partial nitrification and Anammox. It was shown that the optimal air and water ratio in this study was 12:1. Accordingly, the removal loading radio of ammonia was 0.91 kg N·m^-3·d^-1. The removal efficiency of ammonia and TN were 96.86% and 85.47%, respectively.