The nitrite (NO₂⁻) inhibition in anaerobic ammonium oxidation (anammox) process is widely reported. Here, the effects of three pyrolytic biochars (CS300, CS550 and CS800) were investigated to alleviate NO₂⁻ stress on anammox process under exposure of varied NO₂⁻-N concentrations (70, 200, 400 and 600 mg L⁻¹). No nitrite inhibition was observed at 70 mg N L⁻¹. However, the total nitrogen removal efficiency (TNREs) decreased with NO₂⁻-N concentration increased, while the biochar-amended groups achieved higher TNREs than the control (CK). At 200 mg N L⁻¹, the TNREs were 60.2%, 99.0%, 98.5% and 86.6% for CK, CS300, CS550 and CS800, respectively. At 400 mg N L⁻¹, the TNREs were 23.3%, 56.0%, 37.1% and 29.7% for CK, CS300, CS550 and CS800, respectively. At 600 mg N L⁻¹ in which severe inhibition was observed, the TNREs were increased by 231% (p = 0.002), 149% (p = 0.014), and 51.0% (p = 0.166) for CS300, CS550 and CS800, respectively, as compared to CK, with the corresponding specific anammox activity increased by 3.1-, 2,0- and 1.1-folds, respectively. CS300 enriched the relative abundance of Candidatus Kuenenia and increased the gene copies of functional genes (hzsA, hdh, nirS and nirK). Besides, CS300 effectively alleviated the suppression of three membrane-associated enzyme complexes for anammox electron transport chain, indicating the possible contribution of redox-active moieties of CS300 to energy conversion metabolism for mitigating the NO₂⁻-N inhibition. This study provided an effective strategy for alleviating NO₂⁻-N stress by applying an environmentally compatible material (biochar) on anammox process.

亚硝酸盐（NO ₂ ^- ）抑制在厌氧氨氧化（厌氧氨氧化）工艺被广泛地报道。这里，三个热解生物炭（CS300，CS550和CS800）的影响进行了研究，以减轻NO ₂ ^-胁迫对下多样NO的曝光厌氧氨氧化过程₂ ^- -N浓度（70，200，400和600毫克的L ^-1）。在70mg N L ^-1下未观察到亚硝酸盐抑制作用。然而，随着NO ₂ ^-- N浓度的增加，总氮去除效率（TNREs）降低，而生物炭改性组的TNREs高于对照（CK）。在200 mg N L ^-1，CK，CS300，CS550和CS800的TNRE分别为60.2％，99.0％，98.5％和86.6％。在400 mg N L ^-1下，CK，CS300，CS550和CS800的TNRE分别为23.3％，56.0％，37.1％和29.7％。在600 mg N L ^-1（其中观察到严重抑制 ）的情况下，CS300，CS550和CS800的TNRE分别增加231％（p  = 0.002），149％（p  = 0.014）和51.0％（p = 0.166）。与CK相比，相应的特定厌氧氨氧化活性分别提高了3.1倍，2.0倍和1.1倍。CS300富集的相对丰度暂定Kuenenia和增加的功能性的基因的基因拷贝（HZS A，HDH，nir S和nir K）。此外，CS300有效地减轻了三种膜相关酶复合物对厌氧氨氧化电子传输链的抑制作用，表明CS300的氧化还原活性部分对能量转化代谢的缓解NO ₂ ^-- N抑制的可能贡献。这项研究通过在厌氧氨氧化工艺中应用环境相容性材料（生物炭），提供了减轻NO ₂ ^-- N应力的有效策略。