University of Oulu

Elisangela Heiderscheidt, Uzair Akbar Khan, Katharina Kujala, Anna-Kaisa Ronkanen, Heini Postila, Design, construction and monitoring of pilot systems to evaluate the effect of freeze-thaw cycles on pollutant retention in wetlands, Science of The Total Environment, Volume 703, 2020, 134713, ISSN 0048-9697,

Design, construction and monitoring of pilot systems to evaluate the effect of freeze-thaw cycles on pollutant retention in wetlands

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Author: Heiderscheidt, Elisangela1; Khan, Uzair Akbar1; Kujala, Katharina1;
Organizations: 1Water, Energy and Environmental Engineering, Faculty of Technology, University of Oulu, 90014, Finland
Format: article
Version: accepted version
Access: open
Online Access: PDF Full Text (PDF, 0.7 MB)
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Language: English
Published: Elsevier, 2020
Publish Date: 2021-10-31


Due to the complexity of soil freeze/thaw processes and a variety of factors affecting pollutant removal in treatment wetlands, laboratory pilot systems are powerful tools offering a rare opportunity to observe processes that have a significant impact on year-round purification. This paper describes the design, construction, monitoring and operation of two replicate pilot peat-based wetlands subjected to two simulated freeze-thaw cycles. Undisturbed peat soil and pre-treated gold mine process wastewater were collected from a full-scale treatment wetland operating at a mining site in Northern Finland. The wastewater (pH ~7.8, electric conductivity ~3.6 mS/cm) contained a mix of metals/metalloids (e.g. arsenic 12 µg/L, antimony 19 µg/L) and other contaminants e.g. sulphate (~2 g/L). Fluctuations in removal efficiency of target compounds due to freezing and thawing conditions were observed. Overall, removal of sulphate and arsenic decreased during frost periods, while removal of antimony increased. Monitoring data from the full-scale treatment wetland were used to assess the representativeness of the results obtained. Comparisons of seasonal variations in pollutant concentrations in outflow samples from the full-scale wetland and those measured in the pilot wetlands revealed similar fluctuations in removal efficiency during frost and frost-free periods, suggesting that the pilot wetlands simulated the real system rather well. Carefully designed pilot systems can thus be valuable tools for assessing the effect of harsh winter conditions on wetland processes and operation.

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Series: Science of the total environment
ISSN: 0048-9697
ISSN-E: 1879-1026
ISSN-L: 0048-9697
Volume: 703
Article number: 134713
DOI: 10.1016/j.scitotenv.2019.134713
Type of Publication: A1 Journal article – refereed
Field of Science: 218 Environmental engineering
Funding: This study was mainly supported by the project “Development, Evaluation and Optimization of Measures to Reduce the Impact on the Environment from Mining Activities in Northern Regions (Min-North, 2016–2018)”, funded by Interreg Nord 2014-2020 program. Additional support was provided by Maj and Tor Nessling Foundation and Maa-ja vesitekniikan tukiry.
Copyright information: © 2019 Elsevier B.V. This manuscript version is made available under the CC-BY-NC-ND 4.0 license