The nitrite-oxidizing bacteria (NOB) suppression largely restricts the implementation of partial-nitritation and anammox (PN/A) process for low-strength ammonium wastewater treatment. The main goal of the present study was to verify the feasibility of sequencing moving bed biofilm reactor (SMBBR) treating synthetic low-strength ammonium wastewater and the influence of operating conditions and microbial competitions on NOB suppression. The reactor was operated in sequencing batch reactor (SBR) mode with influent ammonium of 50 mg/L, in which the seeded biofilm harvested from an existing similar PN/A reactor treating high-ammonium synthetic wastewater. After increasing the dissolved oxygen (DO) from 0.50 to 1.25 mg/L-with hydraulic retention time (HRT) gradually decreasing from 15 to 5 h-stable nitrogen removal through PN/A was obtained. The long-term operation results showed nitrogen removal efficiencies of 66.23 ± 7.78 % were stably obtained at a relatively low filling ratio of 25 %. The reactor operated in SBR mode allowed NOB suppression and low effluent ammonium due to the ammonium gradient created in cycles. Further, the activity of NOB was controlled at a low level at medium DO concentration. Both ammonium-oxidizing bacteria (AOB) competition acting as DO-cut and anaerobic ammonium-oxidizing bacteria (anammox, AMX) competition acting as nitrite-sink were found to be essential for NOB suppression, and DO-cut played a dominated role. A simple hypothetical microstructure of one-stage PN/A biofilm, assuming AOB layered in the surface of the biofilm while AMX and NOB in the interior, was proposed to define the mechanism of DO-cut and Nitrite-sink. The obtained results demonstrated SMBBR could be regarded as an alternative guideline for successful operation of mainstream PN/A as compared to the integrated fixed film activated sludge (IFAS) systems.

亚硝酸盐氧化细菌 (NOB) 的抑制在很大程度上限制了部分亚硝化和厌氧氨氧化 (PN/A) 工艺在低强度铵废水处理中的实施。本研究的主要目的是验证顺序移动床生物膜反应器 (SMBBR) 处理合成低浓度铵废水的可行性以及操作条件和微生物竞争对 NOB 抑制的影响。该反应器以序批式反应器 (SBR) 模式运行，进水铵为 50 mg/L，其中种子生物膜从现有的类似 PN/A 反应器处理高铵合成废水中收获。在将溶解氧 (DO) 从 0.50 增加到 1.25 mg/L 后，随着水力停留时间 (HRT) 从 15 小时到 5 小时逐渐减少，通过 PN/A 获得了稳定的氮去除。长期运行结果表明，在相对较低的 25% 的填充率下，可稳定获得 66.23 ± 7.78% 的脱氮效率。由于循环中产生的铵梯度，在 SBR 模式下运行的反应器允许 NOB 抑制和低流出铵。此外，在中等 DO 浓度下，NOB 的活性被控制在低水平。发现作为 DO-cut 的氨氧化细菌 (AOB) 竞争和作为亚硝酸盐汇的厌氧氨氧化细菌 (anammox, AMX) 竞争对于 NOB 抑制是必不可少的，并且 DO-cut 起主导作用。提出了一个简单的假设的单级 PN/A 生物膜微观结构，假设 AOB 分层在生物膜的表面，而 AMX 和 NOB 在内部，被提出来定义 DO-cut 和 Nitrite-sink 的机制。