Effects of UV-based oxidation processes on the degradation of microplastic: Fragmentation, organic matter release, toxicity and disinfection byproduct formation

Zhenqi Du; Guifang Li; Shunke Ding; Wuchang Song; Mengyu Zhang; Ruibao Jia; Wenhai Chu

doi:10.1016/j.watres.2023.119983

Effects of UV-based oxidation processes on the degradation of microplastic: Fragmentation, organic matter release, toxicity and disinfection byproduct formation

Water Res. 2023 Jun 15:237:119983. doi: 10.1016/j.watres.2023.119983. Epub 2023 Apr 18.

Authors

Zhenqi Du¹, Guifang Li², Shunke Ding¹, Wuchang Song², Mengyu Zhang³, Ruibao Jia⁴, Wenhai Chu⁵

Affiliations

¹ State Key Laboratory of Pollution Control and Resource Reuse, College of Environmental Science and Engineering, Tongji University, Shanghai, 200092, China; Ministry of Education Key Laboratory of Yangtze River Water Environment, Shanghai, 200092, China.
² Shandong Provincial Water Supply and Drainage Monitoring Centre, Jinan, 250101, China.
³ School of Municipal and Environmental Engineering, Shandong Jianzhu University, Jinan, 250101, China; Shandong Provincial Water Supply and Drainage Monitoring Centre, Jinan, 250101, China.
⁴ School of Municipal and Environmental Engineering, Shandong Jianzhu University, Jinan, 250101, China; Shandong Provincial Water Supply and Drainage Monitoring Centre, Jinan, 250101, China. Electronic address: Jiaruibao1968@163.com.
⁵ State Key Laboratory of Pollution Control and Resource Reuse, College of Environmental Science and Engineering, Tongji University, Shanghai, 200092, China; Ministry of Education Key Laboratory of Yangtze River Water Environment, Shanghai, 200092, China. Electronic address: 1world1water@tongji.edu.cn.

PMID: 37099872
DOI: 10.1016/j.watres.2023.119983

Abstract

The occurrence and transformation of microplastics (MPs) remaining in the water treatment plants has recently attracted considerable attention. However, few efforts have been made to investigate the behavior of dissolved organic matter (DOM) derived from MPs during oxidation processes. In this study, the characteristics of DOM leached from MPs during typical ultraviolet (UV)-based oxidation was focused on. The toxicity and disinfection byproduct (DBP) formation potentials of MP-derived DOM were further investigated. Overall, UV-based oxidation significantly enhanced the aging and fragmentation of highly hydroscopic MPs. The mass scales of leachates to MPs increased from 0.03% - 0.18% at initial stage to 0.09% - 0.71% after oxidation, which were significantly higher than those leached by natural light exposure. Combined fluorescence analysis with high resolution mass spectrometer scan confirmed that the dominant MP-derived DOM are chemical additives. PET-derived DOM and PA6-derived DOM showed inhibition of Vibrio fischeri activity with corresponding EC₅₀ of 2.84 mg/L and 4.58 mg/L of DOC. Bioassay testing with Chlorella vulgaris and Microcystis aeruginosa showed that high concentrations of MP-derived DOM inhibited algal growth by disrupting the cell membrane permeability and integrity. MP-derived DOM had a similar chlorine consumption (1.63 ± 0.41 mg/DOC) as surface water (1.0 - 2.0 mg/DOC), and MP-derived DOM mainly served as precursors for the investigated DBPs. Contrary to the results of previous studies, the DBP yields from MP-derived DOM were relatively lower than those of aquatic DOM under simulated distribution system conditions. This suggests that MP-derived DOM itself rather than serving as DBP precursor might be potential toxic concern.

Keywords: Advanced oxidation processes; Disinfection byproducts; Microplastic; Toxicity; Water treatment.

MeSH terms

Chlorella vulgaris*
Disinfection / methods
Halogenation
Halogens
Microplastics
Plastics
Water Pollutants, Chemical* / analysis
Water Purification*

Substances

Microplastics
Plastics
Halogens
Water Pollutants, Chemical