University of Oulu

Büngener, L., Postila, H., Löder, M. G. J., Laforsch, C., Ronkanen, A.-K., & Heiderscheidt, E. (2023). The fate of microplastics from municipal wastewater in a surface flow treatment wetland. Science of The Total Environment, 903, 166334.

The fate of microplastics from municipal wastewater in a surface flow treatment wetland

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Author: Büngener, Lina1; Postila, Heini1; Löder, Martin G.J.2;
Organizations: 1Water, Energy and Environmental Engineering, Faculty of Technology, 90014 University of Oulu, Finland
2Department of Animal Ecology I and BayCEER, University of Bayreuth, Bayreuth 95440, Germany
3Finnish Environment Institute, Marine and freshwater solutions, Paavo Havaksen Tie 3, P. O. Box 413, FI-90014 Oulu, Finland
Format: article
Version: published version
Access: open
Online Access: PDF Full Text (PDF, 7.8 MB)
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Language: English
Published: Elsevier, 2023
Publish Date: 2023-08-31


Microplastics (MPs) are an anthropogenic pollutant of emerging concern prominent in both raw and treated municipal wastewater as well as urban and agricultural run-off. There is a critical need for the mitigation of both point- and diffuse sources, with treatment wetlands a possible sustainable nature-based solution. In this study, the possible retention of MPs in treatment wetlands of the widely used surface flow (SF) type was investigated. In- and outflow water, as well as atmospheric deposition, at a full-scale reed-based SF wetland (operating as a polishing phase of municipal wastewater treatment) was analyzed for MPs in a size range of 25–1000 μm. FPA-based μFT-IR spectroscopic imaging was used in combination with automated data analysis software, allowing for an unbiased assessment of MP numbers, polymer types and size distribution.

Inflow water samples (secondary treated wastewater) contained 104 MPs m−3 and 56 MPs m−3 in sampling campaigns 1 and 2, respectively. Passage through the SF wetland increased the MP concentration in the water by 92 % during a rain intense period (campaign 1) and by 43 % during a low precipitation period (campaign 2). The MP particle numbers, size and polymer type distribution varied between the two sampling campaigns, making conclusions around the fate of specific types of MPs in SF wetlands difficult.

Atmospheric deposition was measured to be 590 MPs m−2 week−1 during the rain-intense period. Our findings point towards atmospheric deposited MPs as an important factor in the fate of MPs in SF wetlands, causing an increase of MP concentrations, and potentially explaining the variations observed in MP concentrations in wetland effluent and removal efficiency. Furthermore, atmospheric deposition might also be a reason for the considerable inter-study variation regarding MPs removal efficiency in SF wetlands found in the available literature.

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Series: Science of the total environment
ISSN: 0048-9697
ISSN-E: 1879-1026
ISSN-L: 0048-9697
Volume: 903
Article number: 166334
DOI: 10.1016/j.scitotenv.2023.166334
Type of Publication: A1 Journal article – refereed
Field of Science: 218 Environmental engineering
Funding: The study was funded by the European Regional Development Fund (A74546, RaMiKo project 2019–2022).
Copyright information: © 2023 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY license (