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Doktorsavhandling2025Öppen tillgång

Development of innovative treatment techniques for infrastructure contaminated with per- and polyfluoroalkyl substances

Bonnet, Björn

Sammanfattning

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.


Nyckelord

PFAS; decontamination; foam transition; surface analysis; timeof-flight elastic recoil detection; supramolecular assemblies; stabilisation and solidification; lysimeters; variably saturated conditions

Publicerad i

Acta Universitatis Agriculturae Sueciae
2025, nummer: 2025:22
Utgivare: Swedish University of Agricultural Sciences

SLU författare

UKÄ forskningsämne

Miljövetenskap

Publikationens identifierare

  • DOI: https://doi.org/10.54612/a.7ap0tq7hvg
  • ISBN: 978-91-8046-457-4
  • eISBN: 978-91-8046-507-6

Permanent länk till denna sida (URI)

https://res.slu.se/id/publ/132962