溶解氧对短程硝化稳定性及功能菌群的影响

在常温条件下，采用序批式反应器（SBR）研究不同溶解氧（DO）浓度对短程硝化稳定性的影响.在低DO （0.5mg/L）条件下，前75个周期可以一直维持短程硝化，亚硝积累率（NAR）在80%以上，但是随着运行周期增加，NAR逐渐减少，到105个周期已完全变为全程硝化.通过接种同一污泥提高DO浓度到2.5mg/L，经过180个周期，NAR始终在90%以上，能够长期维持短程硝化的稳定运行.通过不同DO条件下AOB和NOB的氧半饱和常数对比分析及qPCR试验研究，结果表明长期低DO条件下容易使Nitrospira的生长获得优势，Nitrospira是影响短程硝化稳定的重要因素，高DO条件下，AOB对溶解氧具有更高的亲和力，通过提高供氧浓度的策略，可以维持短程硝化的长期稳定.

Effect of dissolved oxygen on the stability and functional microbial communities of the partial nitrification

The stability of partial nitrification at different dissolved oxygen (DO) concentration was studied in SBR at room temperature. Under the low DO concentration of 0.5mg/L, the partial nitrification kept stable for 75cycles with the nitrite accumulation rate (NAR) higher than 80%. Until 105cycles, the NAR gradually decreased and the partial nitrification transformed to the complete nitrification. However, using the same sludge, the partial nitrification kept long-term stable of 180cycles under the DO concentration of 2.5mg/L. Furthermore, NAR was higher than 90%. These results indicated under high DO concentration, the stable operation of partial nitrification can be maintained for a long period of time. The oxygen half saturation constant of AOB and NOB, and qPCR tests indicated that low DO might be benefit to the growth of Nitrospira that resulted in the unstable of the partial nitrification. Moreover, under high DO concentration, AOB had higher affinity for oxygen. Therefore, high oxygen concentration could maintain long-term stability of partial nitrification.