Compact Electron Accelerator For The Treatment Of PFAS-Contaminated Water

So-called perpetual chemicals, or PFAS compounds, are a growing environmental problem. An innovative approach for treating water and soil in PFAS-contaminated areas now comes from accelerator physics: High-energy electrons can break down PFAS molecules into harmless components through radiolysis. A study published in PLOS One shows that an accelerator developed at HZB, based on an SHF photoinjector, can provide the necessary electron beam.

PFAS compounds are now detectable in many parts of our environment. These synthetic chemicals accumulate in water and soil and from there enter the food chain. Due to their extremely stable carbon-fluorine bonds, they are hardly broken down by natural processes. Some PFAS are considered harmful to health. The area around the former Tegel Airport, for example, is heavily contaminated, where PFAS entered the soil and groundwater as a result of past fire drills. 

Fast electrons against PFAS

A new approach to tackling this problem now comes from accelerator physics: High-energy electrons can break down PFAS molecules into harmless components through radiolysis. In a feasibility study, a team led by Prof. Dr. Thorsten Kamps has shown that an accelerator developed at HZB, based on an SHF photoinjector, can provide the necessary electron beam. This electron beam must have a specific energy and a high average power. An SHF photoinjector is a novel accelerator concept that uses a superconducting high-frequency resonator with high-frequency electromagnetic fields to accelerate electrons. Because the accelerating field can be continuously switched on, a high average beam power can be generated, as required for water treatment with electron beams.

Flexible concept

“The SHF photoinjector concept is very flexible and perfectly suited for the further development of accelerator-based PFAS water treatment. This allows us to find out which beam parameters optimize the chemical yield for specific PFAS compounds,” says Tasha Spohr, first author of the study.

In a case study, the team compared the PFAS removal filter system currently in use at the former TXL airport with the proposed accelerator concept. "In terms of operating costs, we could be competitive with conventional technology in the near future," says Kamps. "We have shown here that accelerator physics is not only a tool for exciting fundamental research, but can also provide new technologies for tackling pressing societal problems."

Accelerator in a container

The vision for this technology is a compact electron accelerator that fits into a container. This could be deployed at contamination hotspots – such as the former Berlin Tegel Airport – at potentially lower costs and with less effort than conventional remediation techniques using filter systems. While further development work is needed before practical implementation, the study shows that the SRF photoinjector is a suitable platform for systematically optimizing the benefits, efficiency, and costs of such systems.

The study was funded as part of the HGF Hi-Acts initiative .