RMIT University researchers have tested a more effective way to capture microplastics from wastewater, using a combination of microbubbles and nanobubbles to achieve removal rates of more than 90%.

The dual-bubble approach can be adopted by wastewater treatment plants without major infrastructure changes by optimizing existing operating conditions, including air pressure, saturation time and bubble size.

The paper "Micro-Nanobubble Integrated Dissolved Air Flotation: A High-Efficiency Strategy for Microplastic Mitigation in Wastewater," is published in ACS ES&T Water. Lead author, Associate Professor Biplob Pramanik, said the approach suggests a practical way to reduce microplastic pollution—a growing global issue.

"Wastewater treatment plants are a major pathway for microplastics because they slip through filtration processes, posing risks to ecosystems and human health," Pramanik said. He is also the director of RMIT's Water Effective Technology and Tools Research Center.

"Our approach is simple to implement and significantly increases the removal of microplastics during the primary stage of treatment."

The study investigated an enhanced version of dissolved air flotation, a widely used water treatment process that removes contaminants by attaching them to air bubbles and lifting them to the surface.