Impact of dissolved oxygen and loading rate on NH 3 oxidation and N 2 production mechanisms in activated sludge treatment of sewage

作者：Xueyu Zhang, Shida Li, Shaokui Zheng, Shoupeng Duan · 发表于：Microbial Biotechnology · 年份：2020 · DOI：10.1111/1751-7915.13599 · 被引用次数：15 · 研究领域：Wastewater Treatment and Nitrogen Removal、Microbial Fuel Cells and Bioremediation、Water Treatment and Disinfection

Summary Microaerobic activated sludge (MAS) is a one‐stage process operated at 0.5–1.0 mg l −1 dissolved oxygen (DO) aiming at simultaneous nitrification and denitrification. We used molecular techniques and a comprehensive nitrogen (N)‐transformation activity test to investigate the dominant NH 3 ‐oxidizing and N 2 ‐producing mechanism as well as the dominant ammonia‐oxidizing bacteria (AOB) species in sludge samples individually collected from an MAS system and a conventional anoxic/oxic (A/O) system; both systems were operated at a normal loading rate (i.e. 1.0 kg chemical oxygen demand (COD) m −3 day −1 and 0.1 kg NH 4 + ‐N m −3 day −1 ) in our previous studies. The DO levels in both systems (aerobic: conventional A/O system; microaerobic: MAS system) did not affect the dominant NH 3 ‐oxidizing mechanism or the dominant AOB species. This study further demonstrated the feasibility of a higher loading rate (i.e. 2.30 kg COD m −3 day −1 and 0.34 kg NH 4 + ‐N m −3 day −1 ) with the MAS process during sewage treatment, which achieved a 40% reduction in aeration energy consumption than that obtained in the conventional A/O system. The increase in loading rates in the MAS system did not affect the dominant NH 3 ‐oxidizing mechanism but did impact the dominant AOB species. Besides, N 2 was predominantly produced by microaerobic denitrification in the MAS system at the two loading rates.