Partial nitritation (PN)-anaerobic ammonium oxidation (anammox) is a promising pathway for the biological treatment of wastewater. However, the destruction of the system caused by excessive accumulation of nitrate in long-term operation remains a challenge. In this study, PN-anammox was initialized with low inoculation quantity in an air-lift reactor. The nitrogen removal rate of 0.71 kgN/(m³ · d) was obtained, which was far higher than the seed sludge (0.3 kgN/(m³ · d)). Thereafter, excess nitrate build-up was observed under low-loading conditions, and recovery strategies for the PN-anammox system were investigated. Experimental results suggest that increasing the nitrogen loading rate as well as the concentration of free ammonium failed to effectively suppress the nitrite oxidation bacteria (NOB) after the PN-anammox system was disrupted. Afterwards, effluent back-flow was added into the reactor to control the up-flow velocity. As a result, an aggressive discharge of sludge that promoted the synergetic growth of functional bacteria was achieved, leading to the successful restoration of the PN-anammox system. The partial nitritation and anammox activity were in balance, and an increase in nitrogen removal rate up to 1.07 kgN/(m³ · d) was obtained with a nitrogen removal efficiency of 82.4% after recovery. Besides, the proportion of granular sludge (over 200 µm) increased from 33.67% to 82.82%. Ammonium oxidation bacteria (AOB) along with anammox bacteria were enriched in the granular sludge during the recovery period, which was crucial for the recovery and stable operation of the PN-anammox system.

部分硝化（PN）-厌氧铵氧化（anammox）是废水生物处理的有前途的途径。然而，在长期运行中，由于硝酸盐的过多积累而导致的系统破坏仍然是一个挑战。在这项研究中，PN-厌氧氨纶在气举反应堆中以低接种量进行初始化。脱氮率达到0.71 kgN /（m ³ ·d），远高于种子污泥（0.3 kgN /（m ³ ·d）·d））。此后，在低负荷条件下观察到过量的硝酸盐累积，并研究了PN-厌氧氨系统的回收策略。实验结果表明，PN-厌氧氨氮系统被破坏后，增加氮的负载率以及游离铵的浓度不能有效地抑制亚硝酸盐氧化细菌（NOB）。之后，将流出物回流添加到反应器中以控制上升速度。结果，实现了促进功能性细菌协同生长的污泥的积极排放，从而成功恢复了PN-厌氧氨氧化系统。局部硝化和厌氧氨氧化活性达到平衡，氮去除率提高至1.07 kgN /（m ³·d）回收后获得的脱氮效率为82.4％。此外，颗粒污泥（200 µm以上）的比例从33.67％增加到82.82％。在回收期间，氨氧化细菌（AOB）和厌氧氨氧化菌一起富集在颗粒污泥中，这对于PN-厌氧氨氧化系统的回收和稳定运行至关重要。