Ultrasound offers different approach to groundwater treatment

Ben Latham
Thu, 16 Nov 2023 03:00:28 +0000
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Researchers have found ultrasound to be effective against “forever chemicals” in water, paving the way for possible future use on a larger scale.
Credit: Ben Latham | Lantern Reporter

Ultrasonic technology might be the answer to removing per- and polyfluoroalkyl substances — harmful “forever chemicals” commonly known as PFAS — after Ohio State researchers discovered its effectiveness at breaking them down in groundwater.

The researchers used a process called ultrasonic degradation, which uses sound waves to break down chemical bonds. When used on PFAS in water, it produces tiny bubbles which then rapidly collapse, causing hotspots of high temperatures and pressures that work to break the chemical bonds of PFAS.

Billy Fagan, a process engineer at Black and Veatch who received his Ph.D. from Ohio State, said the amount of heat and pressure produced from the bubbles’ collapse is similar to the amount observed on the sun.

“The way you can think about it is like you’re stretching out a rubber band, and you stretch it so much that eventually it can’t take that tension anymore and collapses on itself,” Fagan said. “During [this collapse], PFAS molecules can go onto these bubbles and experience those extreme conditions.”?

According to the Environmental Protection Agency, PFAS, found in tap water, food packaging and other places, are manufactured chemicals that have been used in consumer products and industry for 80 years. The chemicals break down slowly due to their strong carbon-fluorine bond and can accumulate in people, animals and the environment over time, posing potential health problems like cancer or developmental delays in children.

Shannon Thayer, an environmental engineer at Hazen and Sawyer, said the “forever chemicals” are so difficult to get rid of because they do not readily break down in the environment.

“Due to a lack of regulation in the past, there’s a lot that’s already in the ecosystem,” Thayer said. “Without having anything naturally occurring that is going to break it down, it will just continue to cycle in the environment.”

Despite the continued presence of PFAS in everyday life, Fagan said people can still take steps to limit their exposure to them by using online resources to check if a product contains those chemicals.

“I would encourage people to do some research,” Fagan said. “There’s never going to be a complete elimination of your exposure, but you can be mindful of the products that you’re buying.”

Thayer said upscaling ultrasonic technology to use in water treatment plants will be a challenge, but it is not out of the realm of possibilities.

“This technology does have the potential and it shows that it could be used for treating this chemical within water,” Thayer said. “It’s the first step to get to the next step of how this can be implemented on a wider scale.”