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

• Published in: The Science of the total environment 2023-11, Vol.899, p.165714-165714, Article 165714
• Main Authors: Zhang, Le, Wang, Jingxin, Gong, Xia, Song, Yaohua, Li, Danping, Huang, Huajun, Yu, Chenglong, Liang, Ximei, Fang, Hansun
• Format: Article
• Language: English
• Subjects: Microplastics; Removal efficiencies; Removal mechanisms; Sewage treatment; Surface flow wetland
• ISSN: 0048-9697; 1879-1026
• DOI: 10.1016/j.scitotenv.2023.165714

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 (CMPs, in) ranged from 56 ± 6 to 250 ± 14 items L−1. The dominant plastic types were fibers and polyethylene terephthalate (PET). CMPs, 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. [Display omitted] •Fate of MPs flowing through a long-term operation SFW was examined.•MPs' levels in SFW sewage were affected by dressing habit and precipitation.•MPs were effectively removed in an asynchronous manner compared with traditional pollutants.•MPs would be trapped for a certain time in the SFW before flushed out.