Wastewater research targets toxic ‘forever chemicals’

The research team has developed a new machine called a hydrodynamic reactor that uses bubbles which 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.

PFAS chemicals were invented in the 1930s and used in convenience products like waterproof clothing, pizza boxes, nonstick pans, and stain-resistant carpets. Concerns were raised about these chemicals being toxic in the 1970s, and confirmed by scientists in the early 2000s.

According to the Oxford Brookes team, removing PFAS chemicals from water sources is a global challenge as they are released into water sources through industry wastewater, landfills containing contaminated products, domestic wastewater, sewage and agricultural run-off. 

In a statement, professor Iakovos Tzanakis, who specialises in Engineering Materials at Oxford Brookes and is one of the study’s lead researchers, said: “Once contaminated water is released into rivers, lakes and seas, it eventually infiltrates our public water supplies, including our domestic drinking water. Our challenge has been to find a way of effectively treating water to remove PFAS chemicals sustainably and at a scale.

“Until now, methods of removing PFAS from water have been costly and time-consuming using chemicals and restricted to laboratory scale. But research I have carried out with my colleague Dr Morteza Ghorbani has identified a potential solution.”

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

The reactor uses fast-moving liquid in tiny spaces to create and pop lots of small bubbles - a process that helps to clean the water.

When the  ‘eco-friendly and energy-efficient’ hydrodynamic cavitation was tested at the Hammarby Sjöstad wastewater treatment plant in Sweden, the results were ‘far better than expected,’ according to the research team.

The reactor achieved almost a 36 per cent degradation rate of 11 common PFAS variants in just 30 minutes, and didn’t require any additional chemicals.

“Our next step is scaling up our reactor to treat larger volumes of wastewater containing PFAS. We are aiming to treat wastewater containing PFAS volumes up to 20 litres. The reactor for this has already been built. After that, our target is to treat volumes up to 200 litres in a wastewater treatment plant in Sweden,” added Dr Ghorbani.

“Our goal is to boost this promising approach by unveiling the intricate physics that drive the technology through the use of various reactors in different countries. We want to ensure this technology is ready for actual wastewater treatment in the near future and as set by EU 2035 strategy when all PFAS-containing waste must be treated.”

The research, published in the Chemical Engineering Journal, can be accessed in full here.