Innovative method aims to eliminate PFAS from wastewater

Researchers at Oxford Brookes University have developed an innovative method to combat one of the world’s most persistent environmental threats: toxic chemicals in the world’s water supplies.

They developed a new machine called a hydrodynamic reactor that uses bubbles that form and collapse due to changes in pressure, a process called cavitation. The reactor removes toxic per- and poly-fluoroalkyl substances (PFAS), also known as “forever chemicals” from water. The article is published in the Journal of Chemical Engineering.

PFAS chemicals were invented in the 1930s and used in convenience products such as waterproof clothing, pizza boxes, nonstick pans and stain-resistant carpets. Concerns were raised about the toxicity of these chemicals in the 1970s and confirmed by scientists in the early 2000s. They were found to pose a health hazard and have infiltrated water supplies from all over the world. The chemicals are associated with diseases such as ulcerative colitis, thyroid problems, high cholesterol, liver damage and cancer.

Removing PFAS chemicals from water sources is a global challenge. They are released into water sources through industrial wastewater, landfills containing contaminated products, domestic wastewater, sewage and agricultural runoff.

Professor Iakovos Tzanakis, who specializes in engineering materials at Oxford Brookes and is one of the lead researchers, said: “Once contaminated water is released into rivers, lakes and seas, it eventually s seep into our public water supplies, including our domestic drinking water. The challenge has been finding a way to effectively treat water to remove PFAS chemicals sustainably and at scale. »

In the UK, the Royal Society of Chemists has launched a campaign to reduce the levels of PFAS in our water supplies. The EU plans to restrict the use of PFAS chemicals with new rules introduced in 2024. In the United States, legally enforceable levels of PFAS have also been established to protect public safety.

Professor Tzanakis said: “Until now, methods of removing PFAS from water have been expensive and time-consuming, using chemicals and limited to laboratory scale. But research I conducted with my colleague Dr. Morteza Ghorbani identified a potential solution. »

Professor Tzanakis and Dr Ghorbani, Royal Society-Newton Fellow at Oxford Brookes, collaborated with Sabanci University (Turkey), household appliance manufacturer Beko (Turkey), Royal Institute of Technology KTH (Sweden ) and the Swedish Environmental Research Institute IVL to develop and test the hydrodynamic cavitation reactor.

The reactor uses liquid moving quickly through tiny spaces to create and burst many small bubbles, a process that helps clean the water.

Professor Tzanakis said: “This technology has the potential to revolutionize wastewater treatment, making it safer and more sustainable for communities around the world. Advances in green hydrodynamic cavitation offer a scalable alternative to current methods, overcoming its limitations.

When the environmentally friendly and energy-efficient hydrodynamic cavitation reactor was tested at the Hammarby Sjöstad wastewater treatment plant in Sweden, the results were much better than expected.

The reactor achieved a nearly 36% degradation rate of 11 common PFAS variants in just 30 minutes and did not need additional chemicals.

Dr. Ghorbani, who is also affiliated with Sabanci University, said: “The results were impressive. We did not expect this level of PFAS treatment in such a short time. We now explore in depth the fundamental mechanisms of PFAS removal. at Oxford Brookes University to better control and optimize the process.

“Our next step is to scale up our reactor to treat larger volumes of PFAS-containing wastewater. We aim to treat PFAS-containing wastewater volumes of up to 20 liters. The corresponding reactor has already been built After that, our goal is to treat volumes up to 200 liters in a sewage treatment plant in Sweden.

“Our goal is to strengthen this promising approach by unveiling the complex physics that governs the technology through the use of various reactors in different countries. We want to ensure that this technology is ready for real-world wastewater treatment in the near future and as planned by EU 2035. where all waste containing PFAS must be treated.