Remediation of PFAS contaminated soils using a novel soil washing approach: the role of PFAS ageing on desorption and bioavailability in the soil

Perfluorinated alkyl substances (PFAS) have become the focus of attention as persistent environmental contaminants. Current solutions, e.g. isolation or high-temperature treatment, leave the pollution in place or are not applicable at a large scale. A new all-silica Beta zeolite (KU Leuven), an outstanding PFAS adsorbent, could be used to treat contaminated soils by soil washing and concentrating PFAS on the zeolite. The first objective of this study therefore consists of the identification of chemical agents for mobilization of PFAS from soils that also allow selective sequestration of the PFAS from the aqueous leachate on the zeolite. Once suitable agents have been found, they will be tested to transfer PFAS from a homogenized soil column to a zeolite adsorbent bed using a loop-setup. In parallel experiments, the chemical mobilization in the column will be accompagnied by foam injection to reach smaller pores. The effect of foam injection will also be tested on heterogeneous soils in an upscaled setup. Finally, PFAS polluted and cleaned soils will be used to study: (i) the role of age and source of soil PFAS contaminations on the efficiency of PFAS desorption from the soil and (ii) the potential risk of residual PFAS after remediation.