Emerging Compounds Treatment Technologies, Inc. (ECT2) designed, built, and successfully operated a mobile ex situ regenerable anionic exchange resin (AER) treatment system for per- and polyfluoroalkyl substances (PFAS) in groundwater at the Former Naval Air Station Joint Reserve Base Willow Grove. ECT2’s system treated PFAS in 2.5 million gallons of pumped groundwater to U.S. Environmental Protection Agency’s (USEPA) drinking water maximum contaminant levels (USEPA MCLs) for PFAS, demonstrated the repeated reusability of the AER over three loading and regeneration cycles, and generated a PFAS waste concentrate (“still bottoms”) for use in the demonstration of PFAS destruction prototypes through separate vendors including three supercritical water oxidation demonstrations (ER23-8398, ER23-8434, and ER23-8435) and a hydrothermal alkaline treatment (HALT) demonstration.

Regenerable AER is a three-step process to remove and concentrate PFAS from groundwater:

1. PFAS Removal: AER removes PFAS from water via dual ion exchange and hydrophobic adsorption mechanisms.
2. AER Regeneration: The AER is regenerated by desorbing PFAS from the AER with a solvent brine solution, with regenerated AER reused repeatedly for continued PFAS treatment.
3. Regenerant Distillation: Spent regenerant solution is distilled, separating solvent for reuse from a solution of the remaining water, salts, and PFAS (still bottoms). Still bottoms are the high concentration, low volume PFAS waste residual exiting this process.

Operational, technical, and analytical data informed the following key observations:

• Uptime of planned groundwater treatment was 97%. Regeneration events met 100% uptime.
• PFAS treatment objectives were met. Time to breakthrough of MCL compounds were >23,000 bed volumes and projected as high as 35,000 bed volumes (BV); breakthrough of short chain PFAS at 1/10 of the USEPA Tapwater Regional Screening Levels occurred at 7500 BV.
• Treatment cycles were repeatable: Relative standard deviations for time to breakthrough over three cycles ranged from 4% to 27% for all detected compounds and all three AER vessels.
• PFAS adsorbed during treatment were fully recovered by regeneration.
• The overall concentration factor from treated groundwater volume to still bottoms volume was 17,300 observed and 27,000 projected under optimized conditions.
• The lifecycle cost of a regenerable AER treatment system breaks even with single use AER as fast as four years for a 2,000 gallons per minute (gpm) system and 11 years for a 200 gpm system. The lifecycle cost of a regenerable AER system is generally lower than a comparable single use system when >500 cubic feet of media need to be replenished annually.

No major implementation issues occurred during this demonstration. The technology was able to successfully treat PFAS-impacted groundwater to teh regulatory limits. Results from this demonstration directly bolster operational capabilities and warfighter preparedness by mitigating the impacts of PFAS. (Project Completion - 2025)