You’ve found PFAS in your water. Now what? Read the case study below to see how ECT2 went about investigating the problem, cleaning up the source, and providing clean drinking water using multiple PFAS removal technologies.

Background

Since 2014, the United States Air Force Civil Engineering Center (AFCEC) has been conducting on-going response activities to remediate groundwater impacted by poly-and perfluoroalkyl substances (PFAS) at the former Pease Air Force Base in Portsmouth, NH. This source area was impacted by years of firefighting training activities.

Initially, a comprehensive pilot test was conducted to evaluate and compare the effectiveness of multiple treatment technologies. Granular Activated Carbon (GAC) and Ion Exchange (IX) were piloted to find the most economical solution for the USAF. Based on the results, AFCEC chose to install and operate a full-scale regenerable IX resin system to remediate the groundwater.

In parallel, PFAS contamination was detected at elevated levels in the City of Portsmouth (City) public water supply in 2014. The Haven water supply well, located on the Pease Tradeport, was immediately shut down by the City. The source of PFAS contamination was traced back to the historical use of firefighting foam at the nearby base. The City needed to find the best technology to treat their drinking water on site.

Approach

Back at the base, upon completion of the pilot study, a SORBIXTM RePURE regenerable resin system was installed to meet the primary source area remediation objective of treating the groundwater PFOS and PFOA concentration to below the 0.07 µg/l Health Advisory Level. Design, installation and startup of the full-scale SORBIX system was completed from Fall 2017 to Spring 2018.

Based on the successful application of ion exchange resin at the former fire training area, the City decided to run a pilot test as well to evaluate the effectiveness of single-use IiX resin versus bituminous Granular Activated Carbon (GAC). The comparison of the two technologies were at four different empty bed contact times (EBCTs); 2.5, 5, 7.5 and 10 minutes.

Results

Because of the remediation systems installed at the base, the full-scale source area regenerable resin PFAS remediation system has successfully treated groundwater with a total influent average PFAS concentration of 48 µg/l since April 2018. The treated water quality from the SORBIX RePURE resin system has been consistently non-detect for PFOS and PFOA compounds, readily achieving compliance with the 0.07 µg/l HAL target. The ECT2 team has made operational modifications to address and correct minor challenges with the resin regeneration system. Additionally, regenerant recovery and related waste minimization processes have proven highly effective. After more than 16 months of operation, no PFAS waste has needed to be hauled off-site.

The IX resin results were similarly successful in the City’s public water supply pilot test. The influent total PFAS concentration averaged 3.5 µg/l over the course of the year-long evaluation. The IX resin substantially outperformed the GAC on all 12 PFAS that were present at detectable levels. The GAC column was operated until PFOA and PFOS breakthrough reached 0.07 µg/l at the 10-minute EBCT. This occurred at approximately 13,000 bed volumes (BVs), roughly 2.5 months into the test. By contract, the IX resin effluent from the shorted (2.5-minute) EBCT column remained well below the 0.07 µg/l HAL, even after treating more than 171,000 BVs over a 12-month period. Based on the results of the comparative pilot test, the City selected IX resin for full-scale implementation to remove PFAS from the Haven well supply.

The City’s engineer, Weston & Sampson, led the evaluation and attributed the selection of IX resin to the smaller footprint and lower capital and O&M costs associated with ECT2’s technology. The full-scale system is scheduled to commence operation in 2020.

Additional Information Regarding Massachusetts PFAS Rule Changes

What is RSSCT?
RSSCT or Rapid Small Scale Column Testing, is a rapid testing procedure that is used to help understand PFAS treatment performance between adsorbant medias. The medias to be tested are ground up and placed in small columns. Water is then run through the columns. The media is able to remove PFAS from that water until the media runs out of capacity. This measurement of PFAS removal capacity can then be used to help determine which PFAS treatment media would be best suited for that particular water.  

How do I choose a PFAS Testing Technology?
Background chemistry plays a significant role in determining the right PFAS treatment technology for your water source. High chlorides, TOC, and other compounds can drastically impact removal rates changing projected breakthrough and O&M costs dramatically. Download the SORBIX Feedwater Analysis Form to help us get a better understanding of what all is in your water and send it to us at information@ect2.com.

Massachusetts 6 & PFAS6
As you may know, Massachusetts just instituted PFAS guidelines surround 6 compounds including PFOS, PFOA, PFHxS, PFNA, PFHpA and PFDA. The sum of these compounds must be less than 20 nanograms per liter.

EPA 537.1/533
These are the methods used for testing PFAS in water.

Case Studies:

Eielson Air Force Base – Alaska

Opportunity Eielson Air Force Base near Fairbanks, Alaska experienced an unplanned release of 30,000 gallons of wastewater containing concentrated PFAS, and the Air Force Civil Engineer Center sought a system that could demonstrate [...]

Content:

Download the SORBIX Feedwater Analysis Form to help us get a better understanding of what all is in your water.