Stabilization and solidification remediation of soil contaminated with poly- and perfluoroalkyl substances (PFASs)

Remediation methods for soils contaminated with poly- and perfluoroalkyl substances (PFASs) are urgently needed to protect the surrounding environment and drinking water source areas from pollution. In this study, the stabilization and solidification (S/S) technique was tested on aged PFAS-contaminated soil that were artificially spiked with 14 PFAS. To further reduce leaching of PFASs in S/S-treated soil, seven different additives were tested at 2% concentration: powdered activated carbon (PAC), Rembind, pulverized zeolite, chitosan, hydrotalcite, bentonite, and calcium chloride. Standardized leaching tests on S/S-treated soil revealed that leaching of 13 out of 14 target PFASs (excluding perfluorobutane sulfonate (PFBA)) was reduced by, on average, 70% and 94% by adding PAC and Rembind (R). Longer-chained PFASs such as perfluorooctane sulfonate (PFOS), which is considered persistent, bioaccumulative and toxic, were stabilized by 99.9% in all S/S treatments when PAC or Rembind was used as an additive. The S/S stabilization efficiency depended on PFAS perfluorocarbon chain length and functional group, e.g., it increased on average by 11-15 % per CF3-moeity and was on average 49% higher for the perfluorosulfonates (PFCAs) than the perfluorocarboxylates (PFCAs). Overall, the S/S treatment with active carbon-based additives showed excellent performance in reducing leaching of PFASs, without marked loss of physical matrix stability.