Zhong Yuening, Zhang Yibo, Meng Qiyue, Zhang Haoyu, Wu Zhenbing, Dang Chenyuan, Fu Jie
Hubei Key Laboratory of Multi-media Pollution Cooperative Control in Yangtze Basin, School of Environmental Science and Engineering, Huazhong University of Science and Technology, Wuhan, China.
Green Energy Industry Research Centre (GEIRC), Huazhong University of Science and Technology, Wuhan, China.
Appl Environ Microbiol. 2025 Jan 31;91(1):e0151724. doi: 10.1128/aem.01517-24. Epub 2024 Dec 20.
During the coronavirus disease 2019 epidemic, excessive chlorine disinfectants have been used to block the spread of severe acute respiratory syndrome-coronavirus 2, resulting in large amounts of residual disinfectants entering wastewater treatment plants (WWTPs) through sewage systems. So far, no relevant research has been conducted on the impact of chlorine disinfectants on microfauna, an important microbial component in activated sludge treatment systems. This study comprehensively investigated the changes in microfauna habitat, community structure, and colonization mode under the chlorine stress by combining the full-scale WWTP survey and laboratory-scale sequencing batch reactor experiments. The results showed that chlorine disinfectants significantly changed the community structure of microfauna, including decrease in sedentary ciliates and increase in free-living ciliates, amoebas, and flagellates. Besides the disinfection effect of chlorine disinfectants, the microfauna community was also influenced by changes in habitat and bacterial community. The loose structure and excessive extracellular polymeric substance (EPS) of activated sludge caused by chlorination would impact the colonization of sedentary ciliates, while it was conducive to the survival of free-living ciliates due to their predation on EPS as the nutrients. Bacteria in the activated sludge had strong interactions with protozoa, and their changes under chlorine stress directly affected the protozoan community and even indirectly affected the micro-metazoa community through the food chain.
This study revealed that chlorine disinfectant significantly changed microfauna habitat, community structure, and colonization mode in wastewater treatment plants during the coronavirus disease 2019 pandemic. Chlorine disinfectant could destroy the structure and stability of sludge flocs, reduce the abundance of beneficial microfauna in activated sludge, and even affect the colonization of sedentary ciliates on sludge. In addition, chlorine disinfectants might induce environmental and ecological risks related to microfauna, such as elevated suspended solids and release of bacteria and microfauna in the effluents.
在2019年冠状病毒病疫情期间，人们使用了过量的氯消毒剂来阻断严重急性呼吸综合征冠状病毒2的传播，导致大量残留消毒剂通过污水系统进入污水处理厂（WWTPs）。到目前为止，尚未有关于氯消毒剂对活性污泥处理系统中重要微生物组成部分——微型动物影响的相关研究。本研究通过结合全规模污水处理厂调查和实验室规模的序批式反应器实验，全面研究了氯胁迫下微型动物栖息地、群落结构和定殖模式的变化。结果表明，氯消毒剂显著改变了微型动物的群落结构，包括固着型纤毛虫数量减少，自由生活型纤毛虫、变形虫和鞭毛虫数量增加。除了氯消毒剂的消毒作用外，微型动物群落还受到栖息地和细菌群落变化的影响。氯化作用导致活性污泥结构松散和胞外聚合物（EPS）过量，这会影响固着型纤毛虫的定殖，而自由生活型纤毛虫以EPS为营养进行捕食，因此有利于其生存。活性污泥中的细菌与原生动物有很强的相互作用，它们在氯胁迫下的变化直接影响原生动物群落，甚至通过食物链间接影响微型后生动物群落。
本研究表明，在2019年冠状病毒病大流行期间，氯消毒剂显著改变了污水处理厂中微型动物的栖息地、群落结构和定殖模式。氯消毒剂会破坏污泥絮体的结构和稳定性，减少活性污泥中有益微型动物的数量，甚至影响固着型纤毛虫在污泥上的定殖。此外，氯消毒剂可能会引发与微型动物相关的环境和生态风险，如出水悬浮物增加以及细菌和微型动物的释放。
