Bubbles to the rescue

A new approach targets global challenge of toxic ‘forever chemicals’

Is it possible to ever rid our environment of ‘forever chemicals’?

So called ‘forever chemicals’ are a group of synthetic per- and poly-fluoroalkyl substances (PFAS) found in many everyday products such as waterproof clothing, pizza boxes, non-stick pans, and stain-resistant carpets. Their ‘nearly indestructible’ nature and ability to move quickly through the environment have made them a major environmental and health threat.

Researchers at Oxford Brookes University have developed an innovative approach that can destroy these ‘forever chemicals’, in a more efficient and sustainable way. This is achieved through a device called a hydrodynamic reactor that uses bubbles generated by changes in pressure to remove PFAS from contaminated water.

This international project was led by Oxford Brookes’ Newton Research Fellow Dr Morteza Ghorbani and Professor Iakovos Tzanakis together with colleagues based at Sabanci University (Turkey), Royal Institute of Technology (Kungliga Tekniska Högskolan- KTH, Sweden) and the Swedish Environmental Research Institute (IVL). The work was supported by the Science Academy’s Young Scientists Award Program (BAGEP), the Royal Society and the Scientific and Technological Research Council of Turkey Support Program (TUBITAK).

Featured staff

Professor Iakovos Tzanakis

Professor in Engineering Materials

itzanakis@brookes.ac.uk

Removing PFAS from water is a significant global challenge

PFAS were created in the 1930s and have since been used globally in many industrial and commercial sectors due to their useful properties incorporating water-, stain-, and grease-resistance. While concerns about their toxicity emerged in the 1970s, studies in the early 2000s confirmed that these chemicals pose health risks, including links to conditions like ulcerative colitis, thyroid issues, high cholesterol, liver damage, and cancer. Removing PFAS from water presents a significant global challenge, as these synthetic chemicals enter water supplies from various sources, including industrial wastewater, landfills, domestic sewage, and agricultural runoff.

Professor Iakovos Tzanakis, a lead researcher and expert in bubble dynamics, explained that once contaminated water reaches rivers, lakes, and oceans, it can eventually mix into our drinking water. The goal of his work has been to find an effective and sustainable method for cleaning this water on a large scale.

As a way to respond to this global challenge, the Royal Society of Chemists in the UK is advocating for lower PFAS levels in water, while the EU plans to introduce regulations to limit these chemicals by 2024. In the U.S., legal limits on PFAS levels have also been established to safeguard public health.

The hydrodynamic reactor as a safer and more sustainable way for wastewater treatment

The purpose-built hydrodynamic reactor developed at Oxford Brookes University which is also eco-friendly and energy-efficient, uses fast-moving liquid in tiny spaces to create and pop lots of small bubbles - a process that helps to clean the water.

Professor Tzanakis explained: "This technology has the potential to revolutionise wastewater treatment, making it safer and more sustainable for communities around the globe, especially in poor countries, as it does not rely on an electricity supply. Moreover, the advancements in green hydrodynamic cavitation provide a scalable alternative to current methods, overcoming their limitations.”

When the hydrodynamic cavitation reactor was tested at the Hammarby Sjöstad wastewater treatment plant in Sweden, the results were far better than expected: the reactor achieved nearly a 36% degradation rate of 11 common PFAS variants simultaneously in just 30 minutes and didn’t need additional chemicals.

Next steps

The team’s next step involves scaling up the reactor to handle larger volumes of wastewater containing PFAS, with plans to test the scaling up process at a wastewater treatment plant in Sweden. The team want to ensure that this technology is prepared for real-world wastewater treatment in the near future, particularly in alignment with the EU’s 2035 strategy, which mandates the treatment of all PFAS-containing waste and the United Nations Sustainable Development Goal of clean water and sanitation.

Initial findings from this research have been published in the Chemical Engineering Journal, and received a prestigious award from the British Council in collaboration with Sabanci University to enable the team to continue their ground-breaking work.