How To Truly Eradicate PFAS From Our Drinking Water

By Amy Dindal

As so-called “forever chemicals” get more attention from regulators and the public at large, the pressure is on to eliminate these pervasive contaminants — forever.

America’s problem with perfluoroalkyl and polyfluoroalkyl substances, or PFAS, is deep and multifaceted, and there is an urgent need for innovative solutions to PFAS in our society, even as the country waits for the U.S. EPA to determine a regulatory framework. Battelle researchers and scientists have been studying PFAS for years and we continue to invest millions of dollars into progressing the technical assessment, degradation, and destruction of these persistent substances.

Since they were first introduced in the 1940s, the unique physical and chemical properties of these chemicals have made them ubiquitous, as they are especially useful for making consumer products that resist heat, oil, stains, grease, and water. PFAS molecules are made up of a chain of carbon and fluorine atoms linked together — one of the strongest bonds that can be made in organic chemistry — and because of their enduring nature and widespread use, PFAS have accumulated everywhere. They are in soil, surface water, the atmosphere, the ocean, food, humans, and much more, which is why they’ve earned the nickname “forever chemicals.”

More research is needed to fully understand the health impacts of PFAS exposure but according to the EPA,¹ studies show that exposure to PFAS at certain levels can lead to infertility risks, thyroid disease, certain types of cancers, and developmental problems in adolescents. This has led to growing concerns about the amount of PFAS currently in our drinking water. In a 2016 study,² Harvard University researchers found that drinking water supplies serving more than 6 million Americans contain unsafe levels of PFAS, and in 2019, the nonprofit organization Environmental Working Group (EWG) published research³ that indicates PFAS are likely detectable in all of the nation’s major water supplies.

To take action toward reducing PFAS in our water supply, the EPA announced in October that it will set federal drinking water standards in the next two years for two of the most widely studied PFAS chemicals — PFOA and PFOS — and it will require chemical manufacturers to test and publicly report the amount of PFAS contained in the products they make. The EPA also intends to implement measures to prevent the release of PFAS into the environment and expedite the cleanup and disposal of the chemicals at military and industrial sites. The bipartisan infrastructure package, passed in November, includes roughly $10 billion in funding to address PFAS contamination.

Meanwhile, individual states are beginning to move forward with their own PFAS oversight and regulations. Michigan Gov. Gretchen Whitmer recently announced plans to substantially limit the state’s purchase of products made with toxic PFAS chemicals, and environmental groups in Wisconsin are lobbying for interim tests and regulations while the EPA determines the new federal rules. New Jersey has been at the forefront of state regulation — in 2018, it became the first state to establish a drinking water standard for a PFAS chemical when it set a maximum contaminant level for PFNA at 13 parts per trillion (ppt). The state also currently enforces limits of 14 ppt for PFOA.

Getting PFAS Out Of Our Water

There are currently several ways to remove PFAS from drinking water, including treatment with activated carbon, ion exchange resins, or high-pressure membranes. Filtering water through tanks containing granular activated carbon (GAC) is the most common practice. As the water passes through the tanks, PFAS stick to the tiny pieces of GAC, which are an effective adsorbent because they are a highly porous material that provides a large surface area. The filtered water is dispensed at the outlet of the GAC tanks, along with the spent GAC that must be removed. There are GAC systems at water treatment facilities across the U.S., but one of the challenges of this approach is that the spent GAC⁴ must be heated to 1,300°F in an oxygen-free environment to be reactivated.

When PFAS needs to be removed quickly, water can be treated with powder activated carbon (PAC), which is added directly into rapid mix tanks. The PFAS adhere to the powdered carbon as the water passes through; however, just like GAC, the remaining sludge that contains adsorbed PFAS must be properly disposed.

Single-use treatment with positively charged anion exchange resins (AER) is also effective for removing negatively charged contaminants such as PFAS. Small beads made of hydrocarbons work like tiny powerful magnets, attracting and holding PFAS to them to filter the water being treated. The remaining resin is then incinerated rather than regenerated, which means there is no contaminant waste stream to handle, treat, or dispose. The downside is that AER treatment can be quite costly.

GAC and single-use ion exchange treatment technologies effectively extract PFAS from drinking water, but only achieve temporary decontamination and generate problematic secondary waste composed of the adsorption material and concentrated PFAS. This waste must be hauled away to be incinerated or disposed of in a hazardous waste landfill. In addition, these types of removal methods simply transfer PFAS from one media to another, so they’re ultimately just recirculating PFAS in the environment.

Another option for treating water is to filter it through high-pressure membranes, such as nanofiltration or reverse osmosis, which are both extremely effective at removing PFAS. Approximately 80 percent of the water coming into either a nanofiltration or reverse osmosis membrane passes through it, leaving around 20 percent as a high-strength concentrated waste. But because the remaining waste can be difficult to treat or dispose, the EPA believes this approach makes the most sense as point-of-use technology for a homeowner, as the volume of water being treated would be much smaller and the high-strength concentrated waste stream would be much more manageable.

Going Beyond Removal To Total Destruction

Given the persistent properties and potential health risks of PFAS, there is a critical need for innovative technologies that can destroy these substances in contaminated media without transferring them elsewhere or creating harmful byproducts. Battelle has been conducting comprehensive PFAS research for many years and has pioneered numerous assessment and mitigation solutions, including a new, onsite PFAS destruction technology that will permanently close the loop on PFAS decontamination.

This groundbreaking innovation is powered by supercritical water oxidation (SCWO), which breaks the strong carbon-fluorine bonds within PFAS molecules and decomposes the material into a non-toxic waste stream. Water above a temperature of 705°F and pressure of 221.1 bar is considered “supercritical,” a special state that accelerates certain chemical oxidation processes. For example, organic compounds are usually insoluble in liquid water but become highly soluble in supercritical water. And when an oxidizing agent is present, supercritical water dissolves and oxidizes various hazardous organic pollutants.

Battelle’s PFAS Annihilator⁵ system is housed in mobile units that can be deployed to address onsite destruction needs. The technology obliterates PFAS in contaminated water to undetectable levels in seconds, leaving only inert salts and PFAS-free water behind. Once the treated water has been tested to confirm that the PFAS have been eradicated, it can be safely discharged back into the environment. In addition to reducing liability, destroying PFAS to the lowest levels of detection also eliminates the possibility of non-compliance with any future federal regulatory limits.

Regardless of what federal regulations and policies are in the pipeline, development of effective, economically viable destruction technologies is the only way to truly extinguish the threats PFAS potentially pose to human health, and Battelle and others are working to bring these permanent solutions to life. In December 2020, the EPA issued interim guidance⁶ on suggested technologies for PFAS management, and mechanochemical degradation,⁷ supercritical water oxidation,⁸ electrochemical oxidation,⁹ and pyrolysis and gasification¹⁰ were called out as promising destruction solutions that merit further research and analysis.

Wiping out these resilient and pervasive substances won’t be easy, but with the help of science, it can and will be done.

References:

1. https://www.epa.gov/pfas/our-current-understanding-human-health-andenvironmental-risks-pfas
2. https://www.hsph.harvard.edu/news/press-releases/toxic-chemicals-drinkingwater/
3. https://www.ewg.org/research/national-pfas-testing/
4. https://www.battelle.org/markets/environment/investigation-remediation/pfas-assessment-mitigation/granular-activated-carbon-regeneration-technology
5. https://www.battelle.org/markets/environment/investigation-remediation/pfas-assessment-mitigation/pfas-annihilator-destruction-technology
6. https://www.epa.gov/sites/default/files/2021-02/documents/pitt_findings_toolsresources_webinar_02172021_final.pdf
7. https://www.epa.gov/sites/default/files/2021-01/documents/pitt_research_brief_mechanochemical_final_jan_25_2020_508.pdf
8. https://www.epa.gov/sites/default/files/2021-01/documents/pitt_research_brief_scwo_final_jan_25_2021_508.pdf
9. https://www.epa.gov/sites/production/files/2021-01/documents/pitt_research_brief_electrochemical_oxidation_final_jan_25_2021_508.pdf
10. https://www.epa.gov/sites/default/files/2021-01/documents/pitt_research_brief_pyrolysis_final_jan_27_2021_508.pdf

About The Author

Amy Dindal is the PFAS Program Manager for Battelle.