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 NH₃‐oxidizing and N₂‐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 NH₄⁺‐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 NH₃‐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 NH₄⁺‐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 NH₃‐oxidizing mechanism but did impact the dominant AOB species. Besides, N₂ was predominantly produced by microaerobic denitrification in the MAS system at the two loading rates.

中文翻译：

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活性氧处理污泥中溶解氧和负载率对NH3氧化和N2产生机理的影响

微氧活性污泥（MAS）是一个阶段过程，在0.5–1.0 mg l ^-1溶解氧（DO）下运行，旨在同时进行硝化和反硝化作用。我们使用分子技术和全面的氮（N）转化活性测试来研究从MAS单独收集的污泥样品中占主导地位的NH ₃氧化和N _2产生机理以及占优势的氨氧化细菌（AOB）物种。系统和常规的缺氧/有氧（A / O）系统；两种系统均以正常负荷率运行（即1.0 kg化学需氧量（COD）m ^-3 天^-1和0.1 kg NH ₄ ⁺ -N m ^-3 天^-1）在我们以前的研究中。两种系统（需氧：常规A / O系统；微需氧：MAS系统）中的DO水平均不会影响主要的NH ₃氧化机理或主要的AOB种类。这项研究进一步证明了在污水处理过程中，MAS工艺可提高装载量（即2.30 kg COD m ^-3 天^-1和0.34 kg NH ₄ ⁺ -N m ^-3 天^-1）的可行性，该装载量可达到40％与传统的A / O系统相比，减少了通气能耗。MAS系统中负载率的增加不会影响主要的NH ₃氧化机制，但会影响主要的AOB种类。另外，N₂主要由MAS系统中的两个加载速率下的微好氧反硝化产生。