While ion exchange (IX) resins are currently being tested at some sites for PFOA and PFOS treatment (e.g., former Willow Grove NAS, Pease AFB, Chanute AFB), there is currently a lack of public, documented information and guidance concerning (1) the most effective resin types and functional groups for per- and polyfluoroalkyl substance (PFAS) treatment, (2) the effectiveness of different resins on removal of precursor compounds and PFAS other than PFOA and PFOS, and (3) the most effective IX systems for plumes with differing characteristics (e.g., source area vs. dilute plume front).

The objective of this project is to develop one or more treatment trains for PFAS-impacted groundwater consisting of IX using novel resins coupled with electrochemical and/or ultrasonic destruction of PFAS in regeneration solution waste streams. While this project will focus on IX for removal of the main compounds of regulatory concern (PFOA and PFOS), it will also examine treatment of the broader range of PFAS (shorter- and longer-chain perfluoroalkyl acids and sulfonates) and precursors of these compounds (fluorotelomer alcohols [FTOH] and fluorotelomer sulfonates [FTS]) that are coming under increased regulatory scrutiny.

The primary goal is to develop effective IX approaches for PFAS under a variety of different chemical and geochemical conditions, and to provide public data and guidance concerning these technologies. A guidance document and a Microsoft® Excel-based resin selection/design tool for IX treatment of PFAS in groundwater will be two key technology transfer products resulting from this effort.

The technical approach consists of laboratory experiments to identify and test new IX resins combined with a small-scale field study to demonstrate the effectiveness of these resins for removal of a broad range of PFAS from groundwater. The research will be comprised of the following specific technical tasks:

Task 1. Design and select novel resins for PFAS treatment

Task 2. Evaluate and optimize resin regeneration solution and processes

Task 3. Evaluate treatment of resin regeneration waste

Task 4. Perform laboratory pilot-scale evaluation of PFAS treatment train

Task 5. Perform limited field pilot-scale evaluation of PFAS treatment train

The main benefits of this project will be (1) the development and validation of efficient IX resins and resin systems for removing a broad range of PFAS and precursor compounds from groundwater; (2) the development and testing of resin regeneration approaches and processes to destroy accumulated PFAS and precursors in regenerant waste; (3) laboratory and field testing of the resins and processes that are developed; (4) the preparation of a tool that provides technical and cost guidance for IX resin treatment based on a given site’s PFAS distribution profile and groundwater chemistry. The guidance document and resin selection/design tool will allow DoD environmental managers and others to effectively identify the appropriate IX technology for a given PFAS-impacted site. (Project Completion - 2023)