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Introduction to PFAS in Groundwater
Citation:
Rhea, L., T. Lee, AND M. Nadagouda. Introduction to PFAS in Groundwater. U.S. Environmental Protection Agency, Washington, DC, EPA/600/R-22/066, 2022.
Impact/Purpose:
The purpose of this report is to introduce topics relevant to management of groundwater contaminated with per- and poly-fluoroalkyl substances (PFAS).
Description:
PFAS are a family of thousands of chemicals defined as: fluorinated substances that contain at least one fully fluorinated methyl or methylene carbon atom (without any H/Cl/Br/I atom attached to it). They have been used in a multitude of commercial, industrial, and consumer products but some have been discovered to be very toxic. They have been synthesized using either electrochemical fluorination (ECF) or telomerization and the impurities characteristic of each of these processes can be used for source forensics. PFAS are commonly observed in environmental media including soil, surface water and groundwater. Multiple PFAS sources sometimes exist at a single site, and many releases include a mixture of different PFAS as well as co-contaminants such as hydrocarbons and CVOCs. The movement of PFAS that enter the subsurface environment is retarded by their affinity for interfaces between media such as air and water, hydrophobic interactions, and electrophilic interactions. The complexity of PFAS retardation and transformation in the subsurface can make development of a CSM challenging. Some PFAS do not respond well to traditional remedial techniques due to properties such as hydrophobicity, oleophobicity, and exceptional chemical stability. Numerous innovative remedial technologies are in development, but many have only been demonstrated at the laboratory bench scale or do not seem economically viable for scale-up to practical implementation. Currently GAC and IXR are the primary means of PFAS removal, although RO and NF may become more commonly used processes due to their greater removal efficiency if they can be made more economical. Real-world issues such as groundwater co-contaminants, organic material, and geochemistry can affect the efficacy of GAC and IXR. The presence of co-contaminants and organic material can adversely affect the performance of GAC.