Installation, Operation and Startup of World’s First Regenerable Resin System for PFAS Removal

The USAF Civil Engineering Center (AFCEC) is conducting on-going response activities to remove and remediate groundwater impacted by poly- and perfluoroalkyl substances (PFAS) at the former Pease Air Force Base in New Hampshire. The two primary PFAS compounds found at the Site are perfluorooctanoic acid (PFOA) and perfluorooctane sulfonate (PFOS) at combined concentrations (PFOA+PFOS) above the United States Environmental Protection Agency’s (USEPA) Health Advisory Level (HAL) of 0.07 micrograms per liter (µg/l).

AFCEC contracted with Wood Group PLC to conduct a side-by-side pilot test in 2016, comparing the performance of Emerging Compound Treatment Technology’s (ECT) regenerable ion exchange (IX) resin and bituminous granular activated carbon (GAC). The regenerable resin system was selected for full-scale application, based on system performance and a lower overall lifecycle cost than GAC.

A 200-gpm system was provided to meet the primary project objective of producing treated water with combined PFOS plus PFOA concentrations below the 70 ng/l HAL.

The PFAS removal system includes bag filters to remove suspended solids, back-washable GAC pretreatment filtration to remove iron, two parallel trains of lead-lag regenerable IX resin vessels for PFAS removal, an in-vessel regeneration system to strip PFAS from the IX resin, a distillation system to recover and reuse the regenerant solution, a PFAS super-loading system to further reduce PFAS waste volume, and two parallel, single-use IX resin vessels for PFAS polishing. The polish vessels contain a blend of IX resins, tailored to the general water chemistry and PFAS species and their relative concentrations.

The PFAS remediation system has treated more than 9 million gallons of groundwater having a total influent average PFAS concentration of 70 µg/l. The effluent quality from the IX resin system has been consistently non-detect for all 13 monitored PFAS compounds, including the short-chain species, readily achieving compliance with the 70 ng/l HAL target.