Scientists are designing accelerators that one day could help clean the environment

NEWPORT NEWS, Va. – It's been 30 years since a project in Miami-Dade County found that blasting wastewater with electrons could clean it, removing all kinds of stuff, from microorganisms to harsh chemicals.

All that was needed was some intrepid scientist or engineer to come up with an accelerator that was cost-effective, compact and user-friendly enough to clean wastewater on an industrial scale.

The world is still waiting for it.

Many countries have been inching forward in using accelerators for environmental remediation — removing toxic dyes from wastewater at a textile factory in South Korea, for instance, or sulfur dioxides and nitrogen oxides from flue gases at a power plant in Poland. But such devices are still too big and unreliable.

Physicists at Jefferson Laboratory in Virginia are working on two designs that they hope could change that. Fay Hannon is dreaming up a low-energy, portable accelerator for environmental cleanup, while Gianluigi "Gigi" Ciovati is figuring out how to use a commercial cryocooler to stabilize a more powerful accelerator he's designing.

"I'm of a generation where environmental protection really weighs on your mind," Hannon said. "In this case, wastewater treatment is not my specialty, but providing the resource that can do that is."

Hannon considers herself an electrical engineer turned physicist. "I've always been interested in things working nicely and neatly and being able to predict it," she said.

Now she's trying to design a nice, neat and predictable accelerator. "It's the wall-plug power, what you're pulling from the grid to operate this, and how much dose you get from that — that's the real step forward that we're trying to make," Hannon said.

Charles Bott, director of water technology and research at the Hampton Roads Sanitation District, has signed on to consult.

"I think it's important to note that, in my opinion, this is never going to be competitive with our existing technologies for water and wastewater treatment," he said. "It's to go after some very specific contaminants that are hard for our existing processes and technologies to deal with."

Electron beams work by breaking down water molecules into smaller charged particles that can effectively break down most contaminants. One possible target, Bott said, would be 1,4-Dioxane, an industrial chemical found in deodorants, shampoos, cosmetics, dyes, greases, antifreeze and fluids used to de-ice planes. Another would be PFAS, or per- and polyfluoroalkyl substances, found in common consumer goods.

Drinking water can be a source of PFAS, which makes effective water treatment an even greater imperative: The EPA says PFAS were found in the blood of nearly everyone that was tested for them.

Electron beam irradiation is already used in industry and in health care — to pasteurize food and cook dog food, for instance, and to sterilize medical devices. Hannon is also partnering with ScanTech Sciences, a Georgia-based food pasteurization company, to see if her design could sterilize liquid consumables. "Our design is actually a lot more efficient than what is out there right now," she said.

Her accelerator would measure about 2 meters long and fit in a standard shipping container — far smaller than the lab's CEBAF accelerator, which speeds and directs electrons around an underground racetrack nearly a mile long, inside a tunnel lined with the liquid helium infrastructure needed to keep it supercooled. Hers would operate at room temperature at much lower energies, which would also make it safer to use.

She envisions the accelerator deploying to treat graywater at mobile military installations, to clean up hydraulic fracturing fluids and tailings ponds at oil sands mining operations, to strip mercury, nitrogen oxides and sulfur dioxides from flue gases, and to clean wastewater aboard cruise ships.

Ciovati's device is further along in development. His is a higher-powered, superconducting accelerator that would require cooling, but not by costly liquid helium. Instead, it would use an off-the-shelf cryocooler used in devices like MRI machines.

"We saw the convergence of the different technologies as an opportunity to apply our technology to a more direct societal need," Ciovati said.

Because it would operate at higher beam power, his accelerator could treat denser materials such as sludge or medical waste, and a greater flow of pollutants at bigger wastewater treatment or power plants, he said. There's a bonus: The electrons trigger a chemical reaction that converts nitrogen oxides and sulfur dioxides into ammonium nitrate and ammonium sulfate, which are used to make fertilizer.