The unique properties and growing usage of zinc oxide nanoparticles increase their release in municipal wastewater treatment plants.Therefore,these nanoparticles,by interacting with microorganisms,can fail the suitable functioning of biological systems in treatment plants.For this reason,research into the toxicity of ZnO is urgent.In the present study,the toxicity mechanism of ZnO-NPs towards microbial communities central to granular activated sludge (GAS) performance was assessed over 120-day exposure.The results demonstrate that the biotoxicity of ZnO-NPs is dependent upon its dosage,exposure time,and the extent of reactive oxygen species (ROS) production.Furthermore,GAS performance and the extracellular polymeric substances (EPS) content were significantly reduced at 50 mg/L ZnO-NPs.This exposure led to decreases in the activity of ammonia monooxygenase (25.2％) and nitrate reductase (11.9％) activity.The Field emission scanning electron microscopy images confirmed that ZnO-NPs were able to disrupt the cell membrane integrity and lead to cell/bacterial death via intracellular ROS generation which was confirmed by the Confocal Laser Scanning Microscopy analysis.After exposure to the NPs,the bacterial community composition shifted to one dominated by Gram-positive bacteria.The results of this study could help to develop environmental standards and regulations for NPs applications and emissions.

Environmental Health Engineering Research Center,Kerman University of Medical Sciences,Kerman,Iran;Department of Environmental Health Engineering,Faculty of Public Health,Kerman University of Medical Sciences,Kerman,Iran;Faculty of Agriculture and natural resources,Lorestan University,Khorramabad,Iran;Department of Engineering Science,University of Oxford,Parks Road,Oxford OX1 3PJ,UK;School of Environment and Energy,South China University of Technology,Guangzhou 510006,China

[1]Hasti Daraei;Kimia Toolabian;Ian Thompson;Guanglei Qiu-.Biotoxicity evaluation of zinc oxide nanoparticles on bacterial performance of activated sludge at COD,nitrogen,and phosphorus reduction)[J].环境科学与工程前沿,2022(02):50-61

Biotoxicity

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