Innovative method aims to remove PFAS from wastewater

Researchers at Oxford Brookes University have developed an innovative way to tackle 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 gas bubbles that form and collapse due to changes in pressure, a process called cavitation. This reactor removes toxic per- and polyfluoroalkyl substances (PFAS), also known as “forever chemicals,” from water. This paper was published in Chemical Engineering Journal.

PFAS chemicals were invented in the 1930s and used in useful products such as waterproof clothing, pizza boxes, nonstick pots, and stain-resistant carpets. Concerns that these chemicals were toxic were raised in the 1970s and confirmed by scientists in the early 2000s. These seep into water supplies around the world and have been found to pose a health hazard. These chemicals have been linked to diseases such as ulcerative colitis, thyroid disease, elevated cholesterol, liver damage, and cancer.

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

Professor Iakovos Tzanakis, an engineered materials expert at Oxford Brookes University and one of the lead researchers, said: “When contaminated water is released into rivers, lakes or the sea, it ends up in public water supply, including domestic drinking water.” The challenge was to find a way to effectively treat water to remove PFAS chemicals sustainably and at scale.”

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

Professor Tzanakis said: “Until now, methods for removing PFAS from water have been expensive and time-consuming using chemicals, and have been limited to laboratory scale. However, with my colleague Dr Morteza Ghorbani, Research has identified potential solutions.”

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

A reactor uses a liquid moving at high speed in a small space to create and pop lots of tiny bubbles. This is a process that helps purify water.

Professor Zanakis 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 will “It provides a scalable alternative to current methods and overcomes their limitations.”

An environmentally friendly and energy-efficient hydrodynamic cavitation reactor was tested at the Hammarby Sjostad wastewater treatment facility in Sweden, and the results far exceeded expectations.

The reactor achieved nearly 36% degradation of 11 common PFAS variants in just 30 minutes and required no additional chemicals.

Dr. Ghorbani, also at Sabanshi University, said: “The results were impressive. We did not expect to see such levels of PFAS treatment in such a short period of time. “We are investigating the basic mechanism in detail.” Enhanced process control and optimization at Oxford Brookes University.

“Our next step is to scale up the reactor to treat larger quantities of PFAS-containing wastewater. We aim to treat PFAS-containing wastewater in volumes of up to 20 liters. A reactor for this has already been built. Our goal is then to process up to 200 liters in a Swedish sewage treatment plant.

“Our goal is to advance this promising approach by uncovering the complex physics driving the technology through the use of different nuclear reactors in different countries. We want to make sure that in the near future, and by the EU 2035, we have a real wastewater treatment readiness strategy if we have to treat all PFAS-containing waste. ”