Study: Dual bubble method removes over 90% of microplastics from wastewater

A team of researchers in Australia has developed a method to remove more than 90 per cent of microplastics from wastewater using a combination of microbubbles and nanobubbles. The method offers a practical solution to a growing global pollution problem. According to a statement from Australia’s Royal Melbourne Institute of Technology (RMIT) released on Monday, the dual bubble approach can be adopted by wastewater treatment plants by optimising existing operational conditions such as air pressure, saturation time and bubble size, without major changes to infrastructure. “Wastewater treatment plants are a major pathway for microplastics because the particles escape filtration processes, posing risks to ecosystems and human health,” said the study’s lead author, RMIT Associate Professor Biplob Pramanik. The researchers explained that the approach enhances dissolved air flotation, a common treatment process in which air bubbles attach to contaminants and lift them to the surface for removal. They further emphasised that integrating microbubbles and nanobubbles yields significantly higher microplastic elimination rates compared to systems using a single bubble type. Microbubbles provide buoyancy to lift particles, whilst nanobubbles improve particle attachment and aggregation, thereby increasing overall efficiency, according to the study. The study also demonstrated that the system remains effective under realistic wastewater conditions. Organic matter and substances such as fats, oils and grease did not inhibit performance and, in some cases, enhanced elimination by promoting microplastic clumping. The research team said capturing microplastics at the early treatment stage can reduce their accumulation in sewage sludge and limit release into the environment. The team is currently seeking industry partners to validate the approach at scale.