Scientists at the University of Glasgow have discovered a new way to remove a harmful chemical called Bisphenol A (BPA) from water—using only sound waves.
Their method, which doesn’t require adding any chemicals, can get rid of up to 94% of BPA in contaminated water samples.
BPA is widely used in making plastics, with around 10 billion kilograms produced every year.
Although its use in things like food packaging, reusable bottles, and thermal paper receipts has been reduced, decades of production mean it has become a common water pollutant around the world.
When BPA enters the human body, it can build up over time, disrupt hormone production, and harm fetal development. It’s also linked to several serious health problems in adults.
The Glasgow team’s solution uses a process called sonochemistry, which involves using ultrasound waves to trigger chemical reactions.
Their system sends controlled ultrasound through polluted water, creating millions of tiny bubbles.
When these bubbles grow and collapse, they briefly reach extreme temperatures and pressures—conditions similar to those on the surface of the sun. These “hot spots” break BPA molecules apart, turning them into harmless substances like carbon dioxide.
The researchers used two different ultrasound frequencies at the same time, which created a stronger effect than a single frequency could achieve.
In their tests, the combination of 20 kHz and 37 kHz worked best, removing 94% of BPA and reducing overall organic pollution by 67% in just 40 minutes. This was measured using “chemical oxygen demand,” a standard method for checking water quality.
Currently, many water treatment plants use methods like activated sludge or activated carbon to remove BPA. While these can capture the pollutant, the BPA remains in the sludge or carbon and still needs to be safely disposed of. The Glasgow approach is different because it destroys the BPA completely, with no need for extra treatment.
Shaun Fletcher, the study’s lead author, said the method is much simpler than previous ultrasound techniques, which often required extra catalysts or chemicals. “You don’t need to remove anything you’ve added after the process—the ultrasound alone does the job,” he explained.
The team believes this technique could be expanded to deal with other hard-to-remove pollutants, including so-called “forever chemicals” like PFAs. They are already in talks with water companies about how the technology could be used in large-scale treatment systems.
Professor Mark Symes, who leads the research group, says ultrasound won’t replace traditional sewage treatment systems, which work well for most waste.
But he sees great potential for tackling specific, dangerous pollutants that regular systems can’t handle. “The conditions inside those tiny bubbles are literally out of this world, yet we can stand right next to the process and watch the degradation happen without any protective equipment,” he said.
The researchers are now working on scaling up their laboratory system to handle larger volumes of water and exploring its ability to remove a wider range of pollutants.
They hope their work will help make water supplies safer and reduce the health risks of BPA and similar contaminants in the future.
