Nitrite is normally removed slower than nitrate in sulfur-based autotrophic denitrification (SADN), and this may cause nitrite accumulation and decrease the efficiency of nitrogen removal. However, this study shows that nitrite was removed faster by SADN coupled with anaerobic ammonium oxidation (anammox). Both a coupled system and a control system were established to verify the preferential nitrite removal process and to explore the potential causes. The results showed that the removal efficiencies of nitrite and nitrate in SADN of the coupled system were 100% and 69.9%, respectively, under excess nitrite. In anammox effluent, the pH and ORP increased to 8.60 ± 0.11 and −286 ± 21.92 mV, respectively, jointly creating suitable reduction conditions for preferential nitrite removal. Furthermore, the protein-like substances present, C10-HSL and C14-HSL, were increased by 1130.875 a.u. to 5.35 and 1.13 ng L⁻¹, respectively. These changes promoted the activity of nitrite reductase and the abundance of Longilinea, Thiobacillus, and Methyloversatilis. The synergistic effect of material flow and information flow in the coupled system caused preferential nitrite removal. This study provides new insight towards solving the nitrite accumulation problem in the practical nitrogen removal process.

中文翻译：

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受厌氧氨氧化废水影响，硫基自养反硝化结合厌氧氨氧化中亚硝酸盐的去除速度比硝酸盐更快

在硫基自养反硝化（SADN）中，亚硝酸盐的去除速度通常比硝酸盐慢，这可能导致亚硝酸盐积累并降低氮去除效率。但是，这项研究表明，通过SADN结合厌氧铵氧化（anammox）可以更快地除去亚硝酸盐。建立了耦合系统和控制系统，以验证优先的亚硝酸盐去除工艺并探讨潜在的原因。结果表明，在亚硝酸盐过量的条件下，耦合体系SADN中亚硝酸盐和硝酸盐的去除效率分别为100％和69.9％。在厌氧氨气废水中，pH和ORP分别增加到8.60±0.11和-286±21.92 mV，共同创造了合适的还原条件以优先去除亚硝酸盐。此外，存在类似蛋白质的物质，^-1。这些变化促进了亚硝酸盐还原酶的活性和Longilinea， Thiobacillus和Methyloversatilis的丰度。耦合系统中物料流和信息流的协同效应导致优先去除亚硝酸盐。这项研究为解决实际脱氮过程中的亚硝酸盐积累问题提供了新的见识。