Bonnet, Björn
- Department of Aquatic Sciences and Assessment, Swedish University of Agricultural Sciences
Doctoral thesis2025Open access
Development of innovative treatment techniques for infrastructure contaminated with per- and polyfluoroalkyl substances
Bonnet, Björn
Abstract
Per- and polyfluoroalkyl substances (PFAS) are of growing concern due to their persistence, mobility, and toxicity. A major contamination source is aqueous film-forming foam (AFFF) used in firefighting, impacting both infrastructure and soil. This thesis explores methods for decontamination of fire suppression systems and PFAS immobilization in soil.
Laboratory-scale decontamination of AFFF-contaminated stainless-steel pipes showed that butyl carbitol-based solutions removed more PFAS than tap water, with higher temperature enhancing removal. However, surface analysis using time-of-flight elastic recoil detection revealed residual fluorine, posing a risk of PFAS rebound.
In another experiment, a swab sampling method was developed. It was then successfully applied on AFFF-contaminated pipe surfaces to determine total PFAS concentrations.
In laboratory-scale leaching tests of PFAS-contaminated soil, the performance of cement with and without additional activated carbon (AC)- based sorbents was assessed in stabilization and solidification trials. Addition of cement showed higher PFAS leaching (µg/kg) than unsolidified soil. In contrast, the addition of AC-sorbent achieved immobilization efficiencies of >99% for most PFAS compounds. Temporal changes in Kdvalues and mass flux rates suggest a transition to diffusion-controlled release mechanisms over time.
In field-deployed lysimeter experiments, PFAS immobilization using waste-derived biochars and AC-based sorbents under natural, variably saturated conditions resulted in >99% PFAS reduction in leachate for longchain PFAS and 79-99% reduction for short-chain PFAS. A 1-D transport model suggests substantial PFAS retention at the air-water interface.
Keywords
PFAS; decontamination; foam transition; surface analysis; timeof-flight elastic recoil detection; supramolecular assemblies; stabilisation and solidification; lysimeters; variably saturated conditions
Published in
Acta Universitatis Agriculturae Sueciae
2025, number: 2025:22
Publisher: Swedish University of Agricultural Sciences
SLU Authors
UKÄ Subject classification
Environmental Sciences
Publication identifier
- DOI: https://doi.org/10.54612/a.7ap0tq7hvg
- ISBN: 978-91-8046-457-4
- eISBN: 978-91-8046-507-6
Permanent link to this page (URI)
https://res.slu.se/id/publ/132962