activated sludge metagenome Raw sequence reads. activated sludge metagenome

The simultaneous nitrification and denitrification (SND) process is efficient to achieve nitrogen removal via various reactors. Here, a simple internal circulating reactor with a high internal circulation ratio of 36:1 was designed and set up to treat wastewater containing nitrogen and COD, and the performance of the SND process was comprehensively analyzed with a long-term operation. In the bioreactor, simultaneous removal effects of COD (95.2%), TN (87.3%), and NH4+-N (96.9%) were satisfactorily obtained. According to the investigation of nitrogen removal kinetics and nitrogen balance analysis showed that traditional nitrification and denitrification, simultaneous nitrification and denitrification (SND), and nitrogen assimilation accounted for 27.4%, 68.7%, and 3.9% respectively. Microbial community analysis suggested that the proportion of aerobic bacteria (Saprospiraceae) and facultative bacteria (Comamonadaceae) in the reactor was significantly increased, indicating the system has a higher capacity for organic degradation. The relative abundance of denitrifying bacteria and bacterial groups with SND (Comamonadaceae) increased. Furthermore, the regulation of the key enzymes identified that nitrite reduction was the speed-limiting step in the denitrification process. The results of this study suggested that nitrogen removal in wastewater treatment could be accomplished successfully using the developed internal circulating reactor employing the SND process.

同步硝化反硝化（Simultaneous Nitrification and Denitrification, SND）工艺可通过多种反应器高效实现污水脱氮。本研究设计并搭建了一台内部循环比高达36:1的简易内循环反应器，用于处理含氮与化学需氧量（Chemical Oxygen Demand, COD）的废水，并通过长期运行对SND工艺的处理性能开展了全面分析。该生物反应器可实现令人满意的协同去除效果：COD去除率达95.2%，总氮（Total Nitrogen, TN）去除率达87.3%，氨氮（Ammonium Nitrogen, NH4+-N）去除率达96.9%。通过脱氮动力学研究与氮平衡分析可知，传统硝化反硝化、同步硝化反硝化（SND）以及氮同化作用分别占比27.4%、68.7%与3.9%。微生物群落分析结果显示，反应器内好氧菌（腐螺旋菌科，Saprospiraceae）与兼性菌（丛毛单胞菌科，Comamonadaceae）的占比显著提升，表明该系统具备更强的有机污染物降解能力。反硝化细菌以及具备SND功能的菌群（丛毛单胞菌科）的相对丰度均有所上升。此外，关键酶活性分析结果表明，亚硝酸盐还原是反硝化过程中的限速步骤。本研究结果证实，采用所开发的内循环反应器并依托SND工艺，可成功实现污水处理中的脱氮目标。