Concentrating Per- and Polyfluoroalkyl Substances (PFAS) in Municipal Solid Waste Landfill Leachate Using Foam Separation

Large volumes of per- and polyfluoroalkyl substances (PFAS)-contaminated wastewaters, such as municipal solid waste landfill leachates, pose a challenge for PFAS treatment technologies in practice today. In this study, the surfactant properties of PFAS were exploited to concentrate the compounds in foam produced via the bubble aeration of landfill leachate. The effectiveness of the foaming technique for concentrating PFAS varied by compound, with a mean removal percentage (the percent difference between PFAS in leachate before and after foam removal) of 69% and a median removal percentage of 92% among the 10 replicate foaming experiments. This technique appears to be similarly effective at sequestering sulfonates and carboxylate PFAS compounds and is less effective at concentrating the smallest and largest PFAS molecules. The results of this study suggest that for the pretreatment or preconcentration of landfill leachates, foaming to sequester PFAS may provide a practical approach that could be strategically coupled to high-energy PFAS-destructive treatment technologies. The process described herein is simple and could feasibly be applied at a relatively low cost at most landfills, where leachate aeration is already commonplace.