The former Pease Air Force Base (Pease) in Portsmouth, NH, USA, was the site for fire-training activities for the State of New Hampshire for several years. Aqueous Film Forming Foam (AFFF) was used in practice events, eventually working its way into the regional aquifer. The two primary PFAS compounds found at the site are PFOA and PFOS at combined concentrations above the United States Environmental Protection Agency’s (USEPA) Health Advisory Level (HAL) of 0.07 micrograms per liters (µg/l). In 2014, The United States Air Force Civil Engineering Center (AFCEC) began conducting on-going response activities to remediate groundwater impacted by PFAS at Pease. AFCEC moved quickly to begin evaluating sustainable treatment technologies.
The 50-100 ppb influent concentration of total PFAS found in the groundwater presented major challenges for conventional treatment technologies. At the time, Granular Activated Carbon (GAC) was the preferred treatment technology. AFCEC installed a GAC system to begin cleaning up the aquifer but quickly ran into significant operational challenges. The downside to this solution was the large amount of spent GAC waste created. Each vessel only lasted 2-3 weeks before requiring a changeout. A new solution would have to be studied, installed, and operated to effectively clean up the contamination in this aquifer. AFCEC knew they would run into this problem across the country, so they wanted to evaluate alternative solutions that could be applied at various sites nationwide.
AFCEC responded by contracting with Wood Group PLC to conduct a side-by-side pilot study to compare the performance of ECT2’s regenerable ion exchange resin (SORBIXTM RePURE) and GAC. The pilot study targeted groundwater remediation at the site with the following objectives:
1. Demonstrate that both SORBIX A3F Resin and GAC can remove PFAS below achievable laboratory quantification limits, and therefore, USEPA HALs for PFOS and PFOA;
2. Determine the breakthrough curves and removal capacities for PFAS in both resin and GAC; and
3. Demonstrate in-place media regeneration of resin to near-virgin PFAS removal performance.
Based on the superior PFAS removal and lifecycle cost advantage demonstrated by SORBIX RePURE resin, AFCEC moved forward with a full scale plant to treat PFAS and regenerate media in place.
SORBIX RePURE is a patented regenerable ion exchange process that significantly reduces the waste footprint leaving a site. In this process, the resin removes PFAS from the water passing through the vessels. Over time, PFAS begins to leak from the lead vessel into the lag vessel, at which point a regeneration event is triggered. PFAS is then stripped off of the resin using a proprietary regenerant solution. This solution is recovered using distillation and placed back into service for the next regeneration cycle. This process is extremely sustainable in terms of maximizing material reuse and minimizing waste generation. Additionally, the closed loop design of the regeneration process prevents PFAS from being emitted into the atmosphere.
Design, installation and startup of the full-scale SORBIX system was completed in the spring of 2018. To date, the system has treated more than 35 million gallons of PFAS impacted water with an average influent PFAS concentration of 48 µg/l. No PFAS waste has been taken off the site since startup. This is due in part to another proprietary step in the treatment process called SuperLoadingTM. SuperLoading is a patented process that ECT2 developed that further concentrates the PFAS recovered during the regeneration and distillation process.
Not only has the new technology deployed by AFCEC produced excellent results in terms of PFAS removal and waste minimization, it has provided the industry with a demonstrated, sustainable PFAS removal technology capable of consistently achieving non-detect results.
Editor's Note: Scranton Gillette Communications and the SGC Water Group are not liable for the accuracy, efficacy and validity of the claims made in this piece. The views expressed in this content do not reflect the position of the editorial teams of Water & Wastes Digest, Water Quality Products and Storm Water Solutions.