Photochemical behavior of constructed wetlands-derived dissolved organic matter and its effects on Bisphenol A photodegradation in secondary treated wastewater

Hengfeng Zhang; Yucong Zheng; Xiaochang C Wang; Qionghua Zhang; Mawuli Dzakpasu

doi:10.1016/j.scitotenv.2022.157300

Photochemical behavior of constructed wetlands-derived dissolved organic matter and its effects on Bisphenol A photodegradation in secondary treated wastewater

Sci Total Environ. 2022 Nov 1:845:157300. doi: 10.1016/j.scitotenv.2022.157300. Epub 2022 Jul 13.

Authors

Hengfeng Zhang¹, Yucong Zheng¹, Xiaochang C Wang¹, Qionghua Zhang¹, Mawuli Dzakpasu²

Affiliations

¹ Key Laboratory of Northwest Water Resource, Environment and Ecology, MOE, Xi'an University of Architecture and Technology, Xi'an 710055, People's Republic of China; Shaanxi Key Laboratory of Environmental Engineering, Xi'an University of Architecture and Technology, Xi'an 710055, People's Republic of China; International Science & Technology Cooperation Center for Urban Alternative Water Resources Development, Xi'an University of Architecture and Technology, Xi'an 710055, People's Republic of China.
² Key Laboratory of Northwest Water Resource, Environment and Ecology, MOE, Xi'an University of Architecture and Technology, Xi'an 710055, People's Republic of China; International Science & Technology Cooperation Center for Urban Alternative Water Resources Development, Xi'an University of Architecture and Technology, Xi'an 710055, People's Republic of China. Electronic address: mawuli.dzakpasu@xauat.edu.cn.

PMID: 35842169
DOI: 10.1016/j.scitotenv.2022.157300

Abstract

Free water surface flow (FWS) constructed wetlands (CWs) have been broadly applied for polishing secondary treated effluents. Dissolved organic matter derived from FWS CWs (WDOM) plays key roles in contaminants transformations. Conversely, photodegradation could shape the quantity and quality of WDOM, thereby affecting its roles in the photolysis of organic micropollutants (OMPs). Nevertheless, whether and how solar irradiation-induced photodegradation modify the properties of WDOM, and the effects of WDOM on the photodegradation of OMPs remain unclear. This study elucidates the photochemical behavior of two WDOM isolated from field-scale FWS CWs for effluent polishing under simulated sunlight irradiation using spectroscopic tools and high-resolution mass spectra. Furthermore, the roles of WDOM in the photodegradation of Bisphenol A (BPA), as a representative endocrine-disrupting compound (EDC), were comprehensively investigated. Solar irradiation was demonstrated to lower the molecular weight and aromaticity of WDOM, as well as weaken its light absorption. Ultrahigh-resolution mass spectra further confirmed that aromatic and unsaturated structures were susceptible to solar irradiation-induced photodegradation reactions. Subsequently, less aromatic and more saturated structures eventually formed under sunlight irradiation, consistent with the result from spectroscopic characterization. The reactive species produced from WDOM significantly enhanced the photodegradation of BPA with the k_obs noticeably increasing 4-fold compared with the k_obs for direct photolysis. Additionally, ³WDOM* was identified as the dominant reactive species leading to the photolysis of BPA in the presence of WDOM. These findings improve understanding of the phototransformation behavior of WDOM under sunlight irradiation and the roles that WDOM plays in the photochemical fate of coexisting OMPs in CWs treatment systems.

Keywords: Bisphenol A; Constructed wetlands; Dissolved organic matter; Phototransformation; Reactive species.

MeSH terms

Benzhydryl Compounds
Dissolved Organic Matter
Phenols
Photolysis
Wastewater* / chemistry
Water Pollutants, Chemical* / analysis
Wetlands

Substances

Benzhydryl Compounds
Dissolved Organic Matter
Phenols
Waste Water
Water Pollutants, Chemical
bisphenol A