Biodegradation of typical azole fungicides in activated sludge under aerobic conditions

Wenwen Cai; Pu Ye; Bin Yang; Zhouqi Shi; Qian Xiong; Fangzhou Gao; Yousheng Liu; Jianliang Zhao; Guangguo Ying

doi:10.1016/j.jes.2020.11.007

Biodegradation of typical azole fungicides in activated sludge under aerobic conditions

J Environ Sci (China). 2021 May:103:288-297. doi: 10.1016/j.jes.2020.11.007. Epub 2020 Dec 4.

Authors

Wenwen Cai¹, Pu Ye², Bin Yang³, Zhouqi Shi¹, Qian Xiong¹, Fangzhou Gao², Yousheng Liu², Jianliang Zhao², Guangguo Ying⁴

Affiliations

¹ State Key Laboratory of Organic Geochemistry, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou 510640, China; SCNU Environmental Research Institute, Guangdong Provincial Key Laboratory of Chemical Pollution and Environmental Safety & MOE Key Laboratory of Theoretical Chemistry of Environment, South China Normal University, Guangzhou 510006, China; University of Chinese Academy of Sciences, Beijing 100049, China.
² SCNU Environmental Research Institute, Guangdong Provincial Key Laboratory of Chemical Pollution and Environmental Safety & MOE Key Laboratory of Theoretical Chemistry of Environment, South China Normal University, Guangzhou 510006, China; School of Environment, South China Normal University, Guangzhou 510006, China.
³ SCNU Environmental Research Institute, Guangdong Provincial Key Laboratory of Chemical Pollution and Environmental Safety & MOE Key Laboratory of Theoretical Chemistry of Environment, South China Normal University, Guangzhou 510006, China; School of Environment, South China Normal University, Guangzhou 510006, China. Electronic address: bin.yang@m.scnu.edu.cn.
⁴ SCNU Environmental Research Institute, Guangdong Provincial Key Laboratory of Chemical Pollution and Environmental Safety & MOE Key Laboratory of Theoretical Chemistry of Environment, South China Normal University, Guangzhou 510006, China; School of Environment, South China Normal University, Guangzhou 510006, China. Electronic address: guangguo.ying@m.scnu.edu.cn.

PMID: 33743910
DOI: 10.1016/j.jes.2020.11.007

Abstract

Widespread use of azole fungicides and low removal efficiency in wastewater treatment plants (WWTPs) have led to the elevated concentration of azole fungicides in receiving environment. However, there was limited research about the removal mechanism of azole fungicides in the biological treatment of WWTPs. Imidazole fungicide climbazole and triazole fungicide fluconazole were selected to investigate the biodegradation mechanism of azole fungicides in activated sludge under aerobic conditions. Climbazole was found to be adsorbed to solid sludge and resulted in quick biodegradation. The degradation of climbazole in the aerobic activated sludge system was fitted well by the first-order kinetic model with a half-life of 5.3 days, while fluconazole tended to stay in liquid and had only about 30% of loss within 77 days incubation. Ten biotransformation products of climbazole were identified by high resolution mass spectrometry using suspect and non-target screening method. But no biodegradation products of fluconazole were identified due to its limited removal. The possible biodegradation pathways for climbazole were proposed based on the products identification and pathway prediction system, and involves oxidative dehalogenation, side chain oxidation and azole ring loss. The findings from this study suggest that it should be a concern for the persistence of fluconazole in the environment.

Keywords: Activated sludge; Azole fungicides; Biodegradation; Degradation pathway; Products identification.

MeSH terms

Azoles / analysis
Biodegradation, Environmental
Fungicides, Industrial* / analysis
Sewage
Water Pollutants, Chemical* / analysis

Substances

Azoles
Fungicides, Industrial
Sewage
Water Pollutants, Chemical