Dang Chenyuan, Zhang Yibo, Zheng Maosheng, Meng Qiyue, Wang Jia, Zhong Yuening, Wu Zhenbing, Liu Bingchuan, Fu Jie
School of Environmental Science and Engineering, Huazhong University of Science and Technology, Wuhan 430074, China.
College of Environmental Science and Engineering, The Key Laboratory of Resources and Environmental Systems Optimization, North China Electric Power University, Ministry of Education, Beijing 102206, China.
Water Res. 2023 Oct 1;244:120453. doi: 10.1016/j.watres.2023.120453. Epub 2023 Aug 6.
Since the onset of the COVID-19 Pandemic, large amounts of chlorine-containing disinfectants have been used to interrupt the spread of SARS-CoV-2 and residual chlorine eventually entered the hospital or municipal sewage treatment facilities. However, little is known about the effect of chlorine influx on the biological sewage treatment process. Here we investigated the effect of chlorine on the microbiome and the mechanism of microbial chlorine resistance in the activated sludge of the aerobic treatment process, using metagenomic and metatranscriptomic sequencing. We found that chlorine could negatively impact the aerobic treatment performance regarding nitrogen/COD removal with a dose-dependent effect, and the dual effects of chlorine dose and interaction time differentiated the microbial community in activated sludge. The decline of nitrogen/COD removal was attributed to the compressed activity of functional microorganisms, such as the ammonia oxidation bacteria, under chlorinated conditions, and the damage cannot be recovered in a short term. In addition, some microorganisms could survive in chlorinated conditions by up-regulating the chlorine resistance genes (CRGs) expression (approximately 1.5 times) and stimulating new CRGs expression. In particular, species Acinetobacter johnsonii could resist high concentrations of chlorine through various mechanisms, especially the overexpression of efflux pump function encoded by qac genes play a key role. Based on these results, considering the persistence of the epidemic and extensive use of chlorine disinfectants, it cannot be ignored that large amounts of residual chlorine are entering the biological treatment facility, and strictly de-chlorination measures or microbial chlorine resistance regulations before entering should be implemented.
自新冠疫情爆发以来，大量含氯消毒剂被用于阻断严重急性呼吸综合征冠状病毒2（SARS-CoV-2）的传播，残余氯最终进入医院或城市污水处理设施。然而，关于氯流入对生物污水处理过程的影响，人们知之甚少。在此，我们利用宏基因组和宏转录组测序技术，研究了氯对好氧处理过程活性污泥中微生物群落的影响以及微生物抗氯机制。我们发现，氯会对氮/化学需氧量（COD）去除的好氧处理性能产生负面影响，且具有剂量依赖性效应，氯剂量和相互作用时间的双重影响使活性污泥中的微生物群落产生分化。氮/COD去除率的下降归因于氯化条件下功能微生物（如氨氧化细菌）的活性受到抑制，且这种损害在短期内无法恢复。此外，一些微生物可以通过上调抗氯基因（CRGs）的表达（约1.5倍）并刺激新的CRGs表达，在氯化条件下存活。特别是约翰逊不动杆菌可以通过多种机制抵抗高浓度的氯，尤其是qac基因编码的外排泵功能的过表达起关键作用。基于这些结果，考虑到疫情的持续存在和氯消毒剂的广泛使用，大量残余氯进入生物处理设施这一情况不容忽视，应实施严格的脱氯措施或在进入前制定微生物抗氯规定。
