University of Oulu

Uwayezu, J. N., Ren, Z., Sonnenschein, S., Leiviskä, T., Lejon, T., Van Hees, P., Karlsson, P., Kumpiene, J., & Carabante, I. (2024). Combination of separation and degradation methods after PFAS soil washing. Science of The Total Environment, 907, 168137.

Combination of separation and degradation methods after PFAS soil washing

Saved in:
Author: Uwayezu, Jean Noel1; Ren, Zhongfei2; Sonnenschein, Sarah1;
Organizations: 1Waste Science and Technology, Luleå University of Technology, Luleå, Sweden
2Chemical Process Engineering, University of Oulu, Oulu, Finland
3Department of Chemistry, UiT-The Arctic University of Norway, Norway
4Environment Testing, Eurofins, Sweden
Format: article
Version: published version
Access: open
Online Access: PDF Full Text (PDF, 2.3 MB)
Persistent link:
Language: English
Published: Elsevier, 2024
Publish Date: 2023-11-03


The current study evaluated a three-stage treatment to remediate PFAS-contaminated soil. The treatment consisted of soil washing, foam fractionation (FF), and electrochemical oxidation (EO). The possibility of replacing the third stage, i.e., EO, with an adsorption process was also assessed. The contamination in the studied soils was dominated by perfluorooctane sulfonate (PFOS), with a concentration of 760 and 19 μg kg−1 in soil I and in soil II, accounting for 97 % and 70 % of all detected per-and polyfluoroalkyl substances (PFAS). Before applying a pilot treatment of soil, soil washing was performed on a laboratory scale, to evaluate the effect of soil particle size, initial pH and a liquid-to-soil ratio (L/S) on the leachability of PFAS. A pilot washing system generated soil leachate that was subsequently treated using FF and EO (or adsorption) and then reused for soil washing. The results indicated that the leaching of PFAS occurred easier in 0.063–1 mm particles than in the soil particles having a size below 0.063 mm. Both alkaline conditions and a continual replacement of the leaching solution increased the leachability of PFAS. The analysis using one-way ANOVA showed no statistical difference in means of PFOS washed out in laboratory and pilot scales. This allowed estimating twenty washing cycles using 120 L water to reach 95 % PFOS removal in 60 kg soil. The aeration process removed 95–99 % PFOS in every washing cycle. The EO and adsorption processes achieved similar results removing up to 97 % PFOS in concentrated soil leachate. The current study demonstrated a multi-stage treatment as an effective and cost-efficient method to permanently clean up PFAS-contaminated soil.

see all

Series: Science of the total environment
ISSN: 0048-9697
ISSN-E: 1879-1026
ISSN-L: 0048-9697
Volume: 907
Article number: 168137
DOI: 10.1016/j.scitotenv.2023.168137
Type of Publication: A1 Journal article – refereed
Field of Science: 218 Environmental engineering
116 Chemical sciences
Funding: The study is funded by the European Union and the European Regional Development Fund, Interreg Nord programme with the project no NYPS 20202462 (Less-PFAS), Norrbotten County Council and the Swedish Geotechnical Institute (SGI)'s Tuffo research and technology development program.
Copyright information: © 2023 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY license (