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Research article - Peer-reviewed, 2022

Fly ash-based waste for ex-situ landfill stabilization of per- and polyfluoroalkyl substance (PFAS)-contaminated soil

Sörengård, Mattias; Travar, I.; Berggren Kleja, Dan; Ahrens, Lutz


In response to world-wide soil and groundwater contamination per- and polyfluoroalkyl substances (PFAS), stakeholders require immediate mitigation. Soil deposition in landfill is a common mitigation scheme, but PFAS losses occur via landfill leachate. These leaching losses can be reduced by strategically utilizing other deposited waste materials for ex-situ contaminant stabilization. This screening study tested activated carbon (AC) and eight types of wastes (compost, rubber granulate, bentonite clay, industrial sludge, incineration slag, incineration bottom ash (n=4), incineration fly ash-based air pollution control residue (FA-APC) (n=16)) in amending (adding 4%, 5%, 10% or 25% sorbent) field-contaminated (n=19) and PFAS-fortified (n=11) soils. A subset of FA-based residue types, all originating from grate-fire incineration (G-F-I) plants, achieved extraordinarily high removal of PFAS. The removal was up to 98% (25% addition) of the sum of six dominant PFAS for field-contaminated soil and >99% of the sum of 11 PFAS for fortified soil (10/25% addition) (>99.9% for PFOS). Calculated partitioning coefficient revealed significant trends between sorption strength and perfluorocarbon chain length (0.21-0.47 log units per CF2-moiety), indicating high importance of hydrophobic sorption (R2>0.98). However, with incremental G-F-I FA-APC addition this relationship disappeared, indicating an alternative sorption mechanism. The exceptional PFAS sorption by G-F-I FA-APC was not explained by G-F-I surface area, surface charge, soil mineral- and metal composition, or solution DOC, metal, or ion composition (H+, Ca2+, Mg2+, Al3+ and Ba2+). Although the mechanism remains unknown, this study showed that landfill sites can utilize G-F-I FA-APC for ex-situ stabilization at negative cost, thus preventing PFAS-containing leachate.


PFAS; Soil remediation; Stabilization; Landfill; Fly ash; Activated carbon

Published in

Chemical Engineering Journal Advances
2022, volume: 12

Authors' information

Sörengård, Mattias
Swedish University of Agricultural Sciences, Department of Aquatic Sciences and Assessment
Travar, I.
Swedish University of Agricultural Sciences, Department of Soil and Environment
Swedish Geotechnical Institute (SGI)
Swedish University of Agricultural Sciences, Department of Aquatic Sciences and Assessment

UKÄ Subject classification

Environmental Sciences
Environmental Management
Analytical Chemistry

Publication Identifiers


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