低氧条件下A2/O工艺对城市污水脱氮处理的中试研究

以巢湖市某污水处理厂实际污水为处理对象，基于节能降耗的需求开展A²O工艺中试研究.研究结果表明：当溶解氧从2mg/L降至0.5mg/L时，COD和氨氮的去除率分别为80%和90%，去除性能并未受到影响，没有出现亚硝酸积累，而TN的去除率有较大幅度的提升，从15%提升至44%.低溶解氧条件下，温度降低主要对TN去除率产生影响，从夏季的44%下降至冬季的29%，而氨氮的去除率仍维持在90%以上.由于进水碳源不足，出水主要以硝酸盐氮为主，低温脱氮率仅为29%.长期低氧条件下运行，AOB和NOB的优势种属为Nitrosomonadaceae和Nitrospira，相对丰度分别为2.33%和6.40%.系统NOB在数量和动力学性能上均优于AOB，同时发现存在Denitratisoma好氧反硝化菌，其相对丰度为1.59%.研究结果为低氧条件下实现城市污水脱氮提供了理论和实践依据.

A pilot-scale study on nitrogen removal of municipal wastewater by A2/O process under low dissolved oxygen condition

A pilot-scale A²O process was carried out to treat sewage in a wastewater treatment plant in Chaohu City, aiming to save energy. The results showed that when the dissolved oxygen (DO) decreased from 2mg/L to 0.5mg/L, the removal rates of COD and ammonia were 80% and 90%, respectively, meaning the removal performance was not affected, and no nitrite accumulation occurred, in the meantime, the removal rate of TN increased significantly, from 15% to 44%. Under low DO condition,the decrease of temperature mainly affected the TN removal rate, from 44% in summer to 29% in winter, whereas the removal rate of ammonia was still above 90%. Due to the shortage of carbon source, the nitrogen removal rate was only 29% under low temperature, resulting in a high nitrate concentration in the effluent. Under long-term low DO conditions, the dominant microbial species of AOB and NOB were Nitrosomonadaceae and Nitrospira, with relative abundance of 2.33% and 6.40% respectively. NOB is superior to AOB in both quantity and kinetic performance. At the same time, Denitratisoma was found with the relative abundance of 1.59%, which was considered as aerobic denitrifying bacteria. These findings provide theoretical and practical support for nitrogen removal from municipal wastewater under low DO conditions.