The response and anti-stress mechanisms of nitrifying sludge under long-term exposure to Cd Se quantum dots  

作　　者：Linkai Guo Lei Yang Yongxiang Ren Shen Cui Xiaotong Li Jia Wang Jun Lan Haoqi Lu Yuchao Wang 

机构地区：[1]Shaanxi Key Laboratory of Environmental Engineering,Xi’an University of Architecture and Technology,Xi’an 710055,China [2]Key Lab of Northwest Water Resource,Environment and Ecology,Ministry of Education,Xi’an University of Architecture and Technology,Xi’an 710055,China

出　　处：《Journal of Environmental Sciences》2024年第1期174-184,共11页环境科学学报（英文版）

基　　金：supported by the Special Scientific Research Program of Shaanxi Provincial Education Department (No.21JK0716);the Natural Science Basic Research Project of Shaanxi Province (No.2022JM-217);the National Natural Science Foundation of China (No.51878537)。

摘　　要：The wide application of CdSe quantum dots(QDs)increases its stress risk to sewage treatment systems.This study evaluated the response of nitrification performance,floc characteristics and microbial community of nitrifying sludge under long-term exposure to CdSe QDs.Results showed CdSe QDs(≥1 mg/L)would decrease the activity of ammonia monooxygenase(AMO).Under the stress of 30 mg/L CdSe QDs,the activity of AMO was reduced by 66%,while the activities of hydroxylamine oxidase and nitrite oxidoreductase were enhanced by 19.1%and 26%,respectively.Thus,the final nitrification effects were not adversely affected,and the production rates of NO_(2)^(-)-N and NO_(3)^(-)-N were accelerated.Additionally,CdSe QDs improved biomass concentration in sludge and maintained the stability of sludge settleability.High throughput sequencing analysis showed that CdSe QDs evidently reduced the abundance and diversity of microbial community in nitrifying sludge.The abundances of amino acid metabolism and lipid metabolism were enriched.Moreover,CdSe QDs decreased the fluorescence intensity of tryptophan-like protein from 2,326 to 1,179 a.u.in loosely bound extracellular polymeric substances(EPSs)and from 3,792 to 3,117 a.u.in tightly bound EPSs.To relieve CdSe QD stress,the polysaccharide content increased from0.31 to 0.61 mg/g MLSS and intracellular antioxidant defense was activated.With CdSe QD level increasing to 30 mg/L,the total antioxygenic capacity and the activities of catalase were enhanced up to 411%and 143.2%,respectively.Thereby,CdSe QDs had little adverse effects on cell membrane integrity,microbial metabolism and the abundance of Nitrospirae.

关 键 词：Quantum dots Activated sludge Extracellular polymeric substances Microbial community Antioxidant effect 

分 类 号：X703[环境科学与工程—环境工程]