Sorptive removal of per- and polyfluoroalkyl substances (PFAS) in organic-free water, surface water, and landfill leachate and thermal reactivation of spent sorbents

Abstract

This study evaluated the performance of five commercially available granular activated carbons (GACs) derived from different sources for the removal of short-chain and long-chain per- and polyfluoroalkyl substances (PFAS) from raw and pretreated landfill leachate using ozonation to break down organic substances. The adsorption isotherms of PFAS on GAC in organic-free water and surface water were also established to understand the effect of water chemistry. The results demonstrated that bituminous GACs have the highest adsorption capacity compared to GACs made from coconut shells and lignite coal. The GAC adsorption of PFAS in landfill leachate was two orders of magnitude lower than that in surface water. Pretreatment of leachate by ozonation moderately increased the adsorption of PFAS on GAC. This is the first time that PFAS isotherm data are available for mainstream GACs in raw and pretreated landfill leachate samples. Such data can be used to design a GAC treatment system for removing PFAS from leachate. Furthermore, our results showed that GAC contaminated with PFAS in landfill leachate could be effectively regenerated using conventional muffle and tube furnaces, indicating that the presence of other substances in the leachate has no significant impact on the reactivation of the GAC. Lastly, the results indicate that induction heating is an efficient and rapid method for thermally reactivating GAC contaminated with various PFAS.