School of Civil Engineering and Architecture, Zhejiang University of Science and Technology, Hangzhou 310023, China; Department of Environmental Science and Engineering, School of Energy and Environment, Wuxi Engineering Research Center of Taihu Lake Water Environment, Key Laboratory of Environmental Medicine Engineering, Ministry of Education, Southeast University, Nanjing, Jiangsu, 210096, China.
Department of Environmental Science and Engineering, School of Energy and Environment, Wuxi Engineering Research Center of Taihu Lake Water Environment, Key Laboratory of Environmental Medicine Engineering, Ministry of Education, Southeast University, Nanjing, Jiangsu, 210096, China.
Environ Pollut. 2022 Oct 15;311:119930. doi: 10.1016/j.envpol.2022.119930. Epub 2022 Aug 12.
The extensive use of nano-TiO has caused concerns regarding their potential environmental risks. However, the stress responses and self-recovery potential of nitrogen removal and greenhouse gas NO emissions after long-term nano-TiO exposure have seldom been addressed yet. This study explored the long-term effects of nano-TiO on biological nitrogen transformations in a sequencing batch reactor at four levels (1, 10, 25, and 50 mg/L), and the reactor's self-recovery potential was assessed. The results showed that nano-TiO exhibited a dose-dependent inhibitory effect on the removal efficiencies of ammonia nitrogen and total nitrogen, whereas NO emissions unexpectedly increased. The promoted NO emissions were probably due to the inhibition of denitrification processes, including the reduction of the denitrifying-related NO reductase activity and the abundance of the denitrifying bacteria Flavobacterium. The inhibition of carbon source metabolism, the inefficient electron transfer efficiency, and the electronic competition between the denitrifying enzymes would be in charge of the deterioration of denitrification performance. After the withdrawal of nano-TiO from the influent, the nitrogen transformation efficiencies and the NO emissions of activated sludge recovered entirely within 30 days, possibly attributed to the insensitive bacteria survival and the microbial community diversity. Overall, this study will promote the current understanding of the stress responses and the self-recovery potential of BNR systems to nanoparticle exposure.
纳米 TiO2 的广泛应用引起了人们对其潜在环境风险的关注。然而，长期暴露于纳米 TiO2 后，氮去除和温室气体 NO 排放的应激反应和自我恢复潜力尚未得到充分研究。本研究在四个水平（1、10、25 和 50mg/L）下探讨了纳米 TiO2 对序批式反应器中生物氮转化的长期影响，并评估了反应器的自我恢复潜力。结果表明，纳米 TiO2 对氨氮和总氮的去除效率表现出剂量依赖性抑制作用，而 NO 排放却意外增加。促进的 NO 排放可能是由于反硝化过程受到抑制，包括反硝化相关的 NO 还原酶活性降低和反硝化细菌黄杆菌丰度降低。碳源代谢抑制、电子传递效率低下以及反硝化酶之间的电子竞争可能导致反硝化性能恶化。在停止向进水添加纳米 TiO2 后，活性污泥的氮转化效率和 NO 排放在 30 天内完全恢复，这可能归因于细菌的不敏感生存和微生物群落多样性。总体而言，本研究将促进当前对 BNR 系统对纳米颗粒暴露的应激反应和自我恢复潜力的理解。
