State Key Joint Laboratory of Environment Simulation and Pollution Control, School of Environment, Tsinghua University, Beijing, China.
Thunip Co., Ltd., Beijing, China.
Water Environ Res. 2021 Jun;93(6):854-864. doi: 10.1002/wer.1476. Epub 2020 Nov 25.
Spontaneous anammox bacteria enrichment at mainstream conditions was reported in a full-scale Wastewater Treatment Plant (WWTP) in a temperate zone of China. The mainstream anammox was observed after WWTP process retrofit, which constructed a hybrid sludge retention time (SRT) system by providing moving carriers in the anaerobic/anoxic tank and was initially designed to enhance the denitrification process in a conventional anaerobic/anoxic/oxic process. The hybrid SRT system achieved 86.0 ± 4.6% total nitrogen (TN) removal via combined mainstream anammox and conventional denitrification. Autotrophic denitrification via mainstream anammox was confirmed by various shreds of evidence including high-throughput sequencing, specific anammox activity test, and N isotopic tracing. Long-term anammox bacteria existence in the biofilm of the carrier in anoxic zones was detected in a much higher relative abundance compared with other spots. The contribution of anammox activity to TN removal was estimated at around 20%-30%. The reasons leading to spontaneous anammox enrichment were mainly attributed to the carriers for slow-growing bacteria growth and dissolved oxygen gradient in the anoxic tank (caused by intermittent aeration) for nitrite production. The insights of this full-scale case study provide important perspectives for future mainstream anammox application, and also the design of an energy-neutral WWTP process. PRACTITIONER POINTS: Spontaneous mainstream anammox in a full-scale WWTP after its retrofit in a temperate zone of China was reported. Anammox bacteria enrichment and long-term stability on moving carriers at mainstream conditions was achieved by modified hybrid SRT system. The hybrid SRT system achieve stable nitrogen removal even in cold winter and high BOD/N situation by combining mainstream anammox with conventional denitrification. Long term full-scale operation demonstrated excellent nitrogen removal with about 20%-30% contribution of mainstream anammox. This full-scale case study provided perspectives for future optimizing mainstream anammox application, and also energy-neutral WWTP process design.
在中国温带的一个大型污水处理厂（WWTP）中，报道了在主流条件下自发的厌氧氨氧化菌富集。在 WWTP 工艺改造后观察到了主流厌氧氨氧化，该工艺通过在厌氧/缺氧池中提供移动载体构建了混合污泥停留时间（SRT）系统，最初旨在增强传统厌氧/缺氧/好氧工艺中的反硝化过程。混合 SRT 系统通过组合主流厌氧氨氧化和传统反硝化实现了 86.0±4.6%的总氮（TN）去除。通过高通量测序、特定厌氧氨氧化活性测试和 N 同位素示踪等多种证据证实了通过主流厌氧氨氧化的自养反硝化。在缺氧区载体的生物膜中检测到了长期存在的厌氧氨氧化菌，其相对丰度明显高于其他部位。估计厌氧氨氧化活性对 TN 去除的贡献约为 20%-30%。自发厌氧氨氧化富集的主要原因归因于载体为缓慢生长细菌的生长提供了条件，以及缺氧池中的溶解氧梯度（由间歇曝气引起）促进了亚硝酸盐的产生。这项大型案例研究为未来主流厌氧氨氧化的应用以及能源中性 WWTP 工艺的设计提供了重要视角。
