A group of chemicals called PFAS are common in firefighting foams, as well as household products like rain jackets, pizza boxes and non-stick pots and pans. They've been in use since the 1940s and have come to be known as "forever chemicals" because they persist in the environment.
PFAS, which stands for per- and polyfluoroalkyl substances, have made their way into watersheds around the world, and as a recent study found, even into raindrops. Some are considered a threat to human health.
Researchers including Jens Blotevogel, an environmental engineer at Colorado State University, are studying ways to get rid of the compounds.
"There are actually several things we can do to clean water from PFAS, but they are all very expensive, and often even excessively expensive," Blotevogel said.
Special filters are available for use in households and water treatment facilities. But Blotevogel says manufacturers are starting to produce new kinds of PFAS that aren't as "sticky" and therefore harder to pick up in filters. Plus, those filters have to go somewhere.
"They are either disposed of in landfills or sometimes they are incinerated," he said. "But if you dispose of them, you're just transferring the problem into another environment department."
Destroying PFAS is another matter. As the publication Chemical & Engineering News has noted, "At the moment, the only way to truly get rid of PFAS molecules is by incinerating the filter material they are stuck to at temperatures above 1,000 °C (1,800 °F)."
But there are questions about how effective the process is. And as Blotevogel and his colleagues recently wrote in the journal Environmental Science & Technology, the incineration route is "excessively expensive" and considered an "emergency measure."
"So we are basically working on solutions (for) how to make this more cost effective," he said.
In a recent study, Blotevogel and his colleagues focused on a specific type of PFAS called "Gen X." They report that they've developed a two-step method to pull the PFAS out of contaminated water, using a filter that can trap molecules 10,000 times narrower than a human hair, and then use a relatively low-energy process to "unravel" the molecules.
Jinyong Liu, a chemical and environmental engineer with the University of California, Riverside, is also studying this issue.
"The research paper shows a very good effort on PFAS removal and destruction, but like all others' work, no technology is ready for practical treatment yet," said Liu, who is working on using UV light to destroy the chemicals.
Liu said researchers are working on a number of options for separating the problem chemicals from water, and also for destroying them. The challenge is developing a process that is not only cost-effective, but that will also work on a wide array of PFAS, of which there are about 4,700kinds.
"Usually this kind of PFAS contamination is a mixture of multiple structures," Liu said.
According to the Environmental Protection Agency, studies in animals indicate that PFAS exposure can lead to a range of issues from tumors to raised cholesterol levels to "reproductive and developmental, liver and kidney, and immunological effects."
As KRCC has reported, researchers are following the health outcomes of hundreds of people in the Colorado Springs area after firefighting foams used at an Air Force base there contaminated the water supply.
This story was produced by the Mountain West News Bureau, a collaboration between Wyoming Public Media, Boise State Public Radio in Idaho, KUER in Salt Lake City, KUNR in Nevada, the O’Connor Center for the Rocky Mountain West in Montana, and KRCC and KUNC in Colorado.
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