Filtration methods remove harmful ‘permanent chemicals’ from drinking water

Filtration methods remove harmful ‘permanent chemicals’ from drinking water

Los métodos de filtración eliminan los 'químicos permanentes' nocivos del agua potable

Graphically Abstract. Credit: water research (2022). DOI: 10.1016/j.watres.2022.119198

A team of Johns Hopkins engineers has discovered a method to filter out a class of harmful industrial “permanent chemicals” commonly found in the nation’s drinking water.

Known as permanent chemicals because they last for thousands of years, perfluoroalkyl and polyfluoroalkyl substances, commonly known as PFAS, are a group of synthetic organic pollutants that are used in a variety of industrial processes and consumer productsincluding non-stick coatings for cookware, food wrappers, waterproof clothing, and furniture textiles. When these products are improperly used, discarded, or disposed of, PFAS leach into water systems. Once there, they are incredibly difficult to treat due to the unique chemical properties imparted by carbon-fluorine bonds, some of the strongest in chemistry.

The precise amount of PFAS in the nation’s drinking water is unknown, but experts say it ranges from widespread to nearly ubiquitous.

Prolonged, low-concentration exposure to PFAS can make it difficult to immune systemThey interfere with hormones and reduce the effectiveness of vaccines. It can also cause low birth weight and high cholesterol. Those who are exposed to high doses of PFAS at work or because they live near a landfill are at increased risk of kidney cancer, liver damage, testicular cancer, and thyroid disease.

The team compared two of the most promising separation media types (anion exchange resins and granular activated carbon) for removing PFAS. They systematically evaluated how well each of these performed for different types of PFAS in pilot municipal water treatment plants over 15 months, concluding that the resins were more effective at removing most of the PFASs tested.

“You can think of the treatments as large-scale versions of the filters that people use at home to purify their own drinking water. The water is fed in continuously from the top, and we measure the amount of time before we start to detect leakage.” of PFAS from the end of the filter,” says Steven Chow, a research associate in the Johns Hopkins Department of Environmental Health and Engineering and first author of the study. The results appeared in water research.

The researchers say the study is promising because it provides one of the most in-depth laboratory analyzes of a large-scale designed PFAS treatment system to date. Typically, laboratory research has limitations in practical applicability because it is carried out on a small scale for a limited time. And many large-scale engineering systems work by drinking water services they can’t afford to perform in-depth analysis of their systems beyond regulatory requirements, engineers say.

“Our collaboration between academia, industry, and municipal partners allowed the team to answer fundamental questions about how these means of separation work while demonstrating their effectiveness in real-world conditions,” says Chow.

While the technical outlook for filtering PFAS from drinking water is promising, the researchers caution that there are caveats. Such systems can cost millions of dollars to build and operate, in addition to the cost of existing water treatment operations. Once PFAS are removed, the contaminants and the filter used to collect them must be handled and disposed of properly, and because PFAS molecules are so strong, an incredible amount of energy is required to destroy them.

Chow maintains that when it comes to PFAS, prevention may be the best cure.

“PFAS are a generational environmental issue that will take decades to manage and may never be fully resolved,” he says. “The key is forward-thinking policies to reduce the total amount of PFAS released into the environment and avoid an unfortunate substitution of known PFAS with chemicals of unknown or potentially worse outcome.”

The research team also included Kellogg J. Schwab, professor, and Carsten Prasse, assistant professor, both from the Department of Environmental Health and Engineering. The study was conducted in collaboration with Canada-based environmental engineering firm Stantec.


Beauty Products With Fluorinated Ingredients May Also Contain PFAS, Study Reports


More information:
Steven J. Chow et al, Comparative Investigation of PFAS Adsorption on Anion Exchange Resins and Activated Carbon During Long-Term Operation of a Pilot Treatment Plant, water research (2022). DOI: 10.1016/j.watres.2022.119198

Citation: Filtration Methods Remove Harmful ‘Permanent Chemicals’ From Drinking Water (Oct 25, 2022) Retrieved Oct 25, 2022 at https://techxplore.com/news/2022-10-filtration-methods-chemicals. html

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