Removal characteristics of microplastics in sewage flowing through a long-term operation surface flow wetland

Le Zhang; Jingxin Wang; Xia Gong; Yaohua Song; Danping Li; Huajun Huang; Chenglong Yu; Ximei Liang; Hansun Fang

doi:10.1016/j.scitotenv.2023.165714

Removal characteristics of microplastics in sewage flowing through a long-term operation surface flow wetland

Sci Total Environ. 2023 Nov 15:899:165714. doi: 10.1016/j.scitotenv.2023.165714. Epub 2023 Jul 22.

Authors

Le Zhang¹, Jingxin Wang², Xia Gong³, Yaohua Song⁴, Danping Li¹, Huajun Huang¹, Chenglong Yu¹, Ximei Liang⁵, Hansun Fang⁶

Affiliations

¹ Key Laboratory of Poyang Lake Basin Agricultural Resource and Ecology of Jiangxi Province, College of Land Resource and Environment, Jiangxi Agricultural University, Nanchang 330045, China.
² Guangdong Provincial Engineering Technology Research Center of Public Health Detection and Assessment, School of Public Health, Guangdong Pharmaceutical University, Guangzhou 510310, China.
³ College of Chemistry and Material, Jiangxi Agricultural University, Nanchang 330045, China.
⁴ School of Electrical Engineering, Jiujiang Vocational and Technical College, Jiujiang 332007, China.
⁵ College of Animal Science and Technology, Jiangxi Agricultural University, Nanchang 330045, China. Electronic address: willie3@163.com.
⁶ Key Laboratory of Poyang Lake Basin Agricultural Resource and Ecology of Jiangxi Province, College of Land Resource and Environment, Jiangxi Agricultural University, Nanchang 330045, China. Electronic address: fanghansun@163.com.

PMID: 37487891
DOI: 10.1016/j.scitotenv.2023.165714

Abstract

Microplastics (MPs) in sewage pose significant threats to aquatic system. Surface flow wetland (SFW) is a common natural wetland type, and is also used as a cheap and easy-to-build sewage treatment system for small and scattered settlements. However, seasonal variation patterns of MPs in sewage removed by SFW are still limited. Therefore, a field investigation was conducted in an SFW that has been operated for 17 years. The concentration of microplastics in the influent of the SFW (C_{MPs, in}) ranged from 56 ± 6 to 250 ± 14 items L^-1. The dominant plastic types were fibers and polyethylene terephthalate (PET). C_{MPs, in} were high in summer and winter, significantly related to the seasonal dressing habits. The removal efficiencies of MPs in SFW were 48.03-92.32 % in different seasons, and the mechanisms of MP removal were different with traditional pollutants. Before flowing out occasionally or by heavy precipitation, MPs were primarily trapped in the SFW and underwent certain oxidation. Simulation experiments demonstrated that 47.5-92.9 % of MPs would be trapped in the SFW, and plants would significantly enhance the trapping capacities. This study sheds light on the seasonal variation characteristics and patterns of MPs in actual sewage, and clarifies the fate of MPs in a long-term operation SFW.

Keywords: Microplastics; Removal efficiencies; Removal mechanisms; Sewage treatment; Surface flow wetland.