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Abstract：
The effects of biological factors including dissolved oxygen (DO), pH, carbon/nitrogen (C/N) and hydraulic retention times (HRT) on the performance of simultaneous nitrification and denitrification (SND) in a moving bed sequencing batch reactor (MBSBR) were investigated. A low DO was found to be advantageous to the SND in that nitrification was not inhibited, while pH and C/N ratio were shown to have positive effects on SND, and HRT needed to be controlled in a suitable range. A desirable SND efficiency was obtained at a DO of 2.5 mg L-1, pH of approximately 8.0, C/N ratio of 10 and HRT of 10 h in the MBSBR. High-throughput sequencing analysis showed that different operating conditions impacted microbial communities, resulting in different nitrogen removal mechanisms. Autotrophic and heterotrophic nitrification together contributed to the good nitrification performance, while denitrification was conducted by combined anoxic and aerobic processes. Furthermore, the results of principal component analyses (PCA) and the abundance of the predominant nitrification and denitrification genera both showed that DO and HRT might be regarded as the dominant variable factors influencing community structure analysis during SND, while the linear discriminant analysis (LDA) effect size (LEfSe) algorithm showed differences in abundance among the biofilm microbial communities with different DO. Overall, the results of this study improve our understanding of the bacterial community structure with different operating conditions in MBSBRs.
摘要：
包括溶解氧（DO）在内的生物因素的影响，pH值,研究了碳/氮（C/N）和水力停留时间（HRT）对移动床序批式反应器（MBSBR）同时硝化反硝化（SND）性能的影响。发现低DO对SND有利，因为硝化不受抑制，虽然pH和C/N比显示对SND有积极影响，和HRT需要控制在合适的范围内。在MBSBR中，DO为2.5mgL-1，pH约为8.0，C/N比为10，HRT为10小时时，获得了理想的SND效率。高通量测序分析表明,不同操作条件对微生物群落的影响,导致不同的脱氮机制。自养和异养硝化共同促进了良好的硝化性能，反硝化是通过缺氧和好氧相结合的过程进行的。此外，主成分分析（PCA）和主要硝化和反硝化属的丰度均表明，在SND过程中，DO和HRT可能被视为影响群落结构分析的主要变量因素，而线性判别分析（LDA）效应大小（LEfSe）算法显示出不同DO的生物膜微生物群落之间的丰度差异。总的来说,这项研究的结果提高了我们对MBSBR中不同操作条件下细菌群落结构的理解。
