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Per-and polyfluoroalkyl substances (PFAS) is a family of widespread organic chemicals that are toxic, bioaccumulate, and extremely soluble in water and stable in the environment. PFAS have many health effects for humans, including negative impacts immune system, liver, cancer, and infertility. There are thousands of individual PFAS molecules, but the two most studied and widespread are perfluorooctane sulfonate (PFOS) and perfluorooctanoic acid (PFOA), which contain eight carbons.
The most cost-effective way to control the release of PFAS to the environment is to immobilize the PFAS in the waste (i.e., soil, sediment, spent AC, RO concentrate, etc.) using stabilization/solidification (S/S). S/S is a long-used method of reducing leaching of wastes, and involves adding sorbent that adsorb PFAS, thereby removing them from the aqueous, mobile phase. Cementing agents must also be added to absorb water, which both reduces leaching and increased the strength of the treated material so it can be easily handled and meets the basic free-water requirement for landfilling wastes (the paint-filter test).
This research project analyzed PFAS leaching data from ten soils and ten biosolids collected, treated with S/S, and subjected to leaching using both TCLP and SPLP. PFOA and PFOS were the only PFAS analyzed in the leachate, and SPLP consistently leached more of both than did TCLP for all the soils biosolids tested. A literature review and analysis were conducted to explain this phenomenon.
Aljabri, Samiya, "Immobilization of Per-and Polyfluoroalkyl Substances (PFAS) in PFAS-Contaminated Materials" (2021). Honors Theses. 3484.