Researchers at the Helmholtz-Zentrum Dresden-Rossendorf (HZDR) have developed two new processes: Using hydrodynamic cavitation and cold atmospheric plasma combined with gas dispersion, they are looking to break down per- and polyfluoroalkyl substances (PFAS), industrial chemicals that are extremely resistant to chemical degradation. To support this effort, experts from the Helmholtz Centre for Environmental Research (UFZ) ran analyses that confirmed the degradation of PFAS and the release of fluoride. Once they reach market maturity, these processes could be used in industry, significantly reducing the release of PFAS into bodies of water (DOI: 10.1038/s41598-026-57490-6; DOI: 10.1016/j.ceja.2026.101046).
While some PFAS are suspected of altering genetic material and increasing the risk of cancer, the biological effects of many others remain unknown. This group of substances comprises more than 10,000 short- and long-chain industrial chemicals which owe their exceptional chemical resistance to their highly stable carbon-fluorine bonds. PFAS enter rivers and oceans via wastewater and are spreading worldwide. High concentrations of PFAS have also recently been detected in the Elbe River – a potential health hazard to plants, animals and humans alike.
In the context of the “National Water Strategy” to secure Germany’s drinking water supply and protect its bodies of water, researchers at HZDR are investigating how to reduce the burden on water bodies and specifically, how to systematically break down these “forever chemicals”. In a preliminary study, launched in 2022, a research team led by postdoctoral researcher Dr. Ysabel Huaccallo-Aguilar used a process known as hydrodynamic cavitation to degrade PFAS.
Cavitation breaks down stable bonds
“In hydrodynamic cavitation, we pass PFAS-enriched water through a constriction, generating small vapor bubbles,” explains Dr. Sebastian Reinecke, head of the Department of Water and Environmental Technologies at HZDR. Since long-chain PFAS are surface-active, they attach to the bubbles. “When the bubbles burst under the rising ambient pressure in the water downstream of the constriction, the PFAS that are attached to the bubbles are exposed to local temperature spikes of several thousand degrees Celsius,” Reinecke explains. At the same time, cavitation produces highly reactive hydroxyl radicals that react non-specifically with nearby substances. “Our hypothesis is that they attack the intermediate products, significantly boosting PFAS degradation.”
Ysabel Huaccallo-Aguilar and her colleagues were able to demonstrate that the process did break down PFAS in tap water while mineralizing organically bound fluorine. The longer the duration of the treatment, the higher the continuous increase in fluoride concentration in the solution. For their experiments, the researchers used perfluorooctane sulfonate (PFOS), a particularly persistent and well-studied compound from the PFAS group. By the end of the experiment, they were able to break down approximately 37 percent of the dissolved PFOS molecules at a stable degradation rate. “We are now conducting follow-up experiments to increase the degradation rate,” Reinecke explains. “Our goal is to improve the process to a degradation rate of more than 80 percent of the PFAS in the solution and mineralizing more than 50 percent of the fluorine that is bound in the chemicals – that means, breaking down the carbon-fluorine bonds that are typical of PFAS.”
Efficient PFAS degradation with highly reactive plasma species
In another series of experiments, environmental engineer Dr. Amit Kumar used cold atmospheric plasma in combination with gas dispersion to degrade PFAS. The advantage of this process is that it operates under ambient conditions and requires neither catalysts nor additional chemicals. In his PhD research, Kumar had already investigated ways of degrading micropollutants using the reactive chemical species that are generated in the plasma. He now applied his findings to this experiment. “We generated plasma at the water surface while simultaneously introducing gas into the PFAS-contaminated water,” says Sebastian Reinecke, explaining the experimental setup. “The PFAS attach to the surface of the gas bubbles. As they rise, the water is constantly circulated. This brings the PFAS to the surface, where they are broken down in the plasma.”
This method made it possible to almost completely degrade both long- and short-chain PFAS. About 35 percent of the fluorine atoms bound in these “forever chemicals” were released as fluoride salts. “While this method has significantly faster reaction kinetics than cavitation, it also consumes far more energy per volume unit,” Reinecke notes. “In addition, the process generates numerous transformation products that we have not yet been able to investigate in detail – for instance, gaseous compounds that form during the reaction.” The researchers are currently conducting further test series to find out whether the process produces any substances that may pose a health hazard, and if so, how to avoid it.
Synergies from combining plasma and cavitation
The researchers are currently working to scale up the process for larger volumes of contaminated water. Using multiple electrodes and a technical gas injector, they are gradually increasing the reaction volume from about 50 milliliters to five liters. The plan is to combine plasma technology with cavitation. “I believe we’ll achieve high degradation rates by combining the highly reactive species from the plasma with the effects of cavitation,” says Reinecke. If they succeed in merging the benefits of both methods into a single approach, they might create a whole new, efficient PFAS removal technology for contaminated water.
Publications:
Amit Kumar, Ysabel Huaccallo-Aguilar, Holger Kryk, Uwe Hampel, Sebastian Felix Reinecke: Enhanced degradation and defluorination of perfluorooctane sulfonate (PFOS) in tap water using gas-dispersed cold atmospheric plasma, in Scientific Reports , 2026 (DOI: 10.1038/s41598-026-57490-6).
Amit Kumar, Anett Georgi, Ysabel Huaccallo-Aguilar, Markus Meier, Holger Kryk, Sebastian Felix Reinecke, Uwe Hampel: Degradation and defluorination of perfluorooctane sulfonate (PFOS) forever chemical in water using hydrodynamic cavitation treatment, in Chemical Engineering Journal Advances , 2026 (DOI: 10.1016/j.ceja.2026.101046 ).
Funding:
This research was funded by the Helmholtz Association’s Impulse and Networking Fund via the Clean Water Technology Lab (CLEWATEC), a Helmholtz Innovation Lab, under reference number HIL-A02. The projects “HyKaPro SAB-EFRE” and “Plasma4PFAS SAB-EFRE” are co-financed by the European Union and tax revenue as approved by the Saxon Parliament in its state budget.
Further information:
Dr. Sebastian Reinecke | Head
Department of Water and Environmental Technologies
Institute of Fluid Dynamics at HZDR
Phone: +49 351 260 2320 | Email: s.reinecke@hzdr.de
Susann Riedel | Project Manager
Institute of Fluid Dynamics at HZDR
Phone: +49 351 260 3766 | Email: s.riedel@hzdr.de
Media Contact:
Simon Schmitt | Head
Communications and Media Relations at HZDR
Phone: +49 351 260-3400 | Email: s.schmitt@hzdr.de
The Helmholtz-Zentrum Dresden-Rossendorf (HZDR) performs – as an independent German research center – research in the fields of energy, health, and matter. We focus on answering the following questions:
To help answer these research questions, HZDR operates large-scale facilities, which are also used by visiting researchers: the Ion Beam Center, the Dresden High Magnetic Field Laboratory and the ELBE Center for High-Power Radiation Sources. HZDR is a member of the Helmholtz Association and has seven sites (Dresden, Freiberg, Görlitz, Grenoble, Leipzig, Rostock, Schenefeld near Hamburg) with almost 1,500 members of staff, of whom about 700 are scientists, including 200 Ph.D. candidates.
Scientific Reports
Experimental study
Not applicable
Enhanced degradation and defluorination of perfluorooctane sulfonate (PFOS) in tap water using gas-dispersed cold atmospheric plasma
13-Jun-2026