RMIT dual-bubble method removes over 90% of microplastics from wastewater
RMIT University reported on July 5, 2026 that a dual-bubble dissolved air flotation method removed more than 90% of microplastics from wastewater.
Photo by Alfo Medeiros on Pexels
RMIT University reported on July 5, 2026 that a dual-bubble treatment method achieved microplastic removal of more than 90% from wastewater by combining microbubbles and nanobubbles. The approach builds on dissolved air flotation (DAF), a process already used in water treatment, and was tested on synthetic wastewater. The findings were published in the journal “ACS ES&T Water” by researchers at RMIT’s Water Effective Technology and Tools Research Centre in Melbourne, Australia.
The result addresses a persistent gap: conventional treatment plants let a share of microplastics pass into rivers and oceans. The team says the dual-bubble method can be added to existing plants by tuning current operating conditions rather than installing new infrastructure.
How the dual-bubble method improves microplastic removal
The two bubble types do different jobs. Microbubbles provide the lifting force that carries plastic particles to the surface for skimming, while nanobubbles improve how particles attach and clump together, raising overall capture. In the study, microbubbles measuring 105 plus or minus 15 micrometres, generated at 5 bar with a 5-minute saturation time, removed 87% of 100-micrometre polyethylene (PE) particles and 91% of polystyrene (PS) particles through buoyant flotation. Adding nanobubbles lifted combined removal above 90%.
The tested conditions and results are summarised below.
| Parameter or result | Value |
|---|---|
| Microplastics tested | 100-micrometre polyethylene (PE) and polystyrene (PS) |
| Microbubble size | 105 plus or minus 15 micrometres |
| Saturation pressure | 5 bar |
| Saturation time | 5 minutes |
| Polyethylene removal (microbubble flotation) | 87% |
| Polystyrene removal (microbubble flotation) | 91% |
| Combined micro- and nanobubble removal | More than 90% |
Source: “ACS ES&T Water” (2026); RMIT University (July 5, 2026).
Why it matters for wastewater treatment
Because the method extends dissolved air flotation, which many plants already run, RMIT says it could be adopted without major infrastructure changes by adjusting air pressure, saturation time and bubble size. That lowers the barrier to capturing more microplastics before treated water is discharged. Keeping plastics out of waterways is one part of the broader response to the pressure on freshwater systems, a theme covered in Winss reporting on a major water crisis. Recovering and reusing materials rather than releasing them also fits the logic of circular economy strategies.
About the RMIT study
The research was led by Associate Professor Biplob Pramanik, director of RMIT University’s Water Effective Technology and Tools Research Centre, with Dr Sirajum Monira, who completed the work during her PhD at RMIT. The study, “Micro-Nanobubble Integrated Dissolved Air Flotation: A High-Efficiency Strategy for Microplastic Mitigation in Wastewater,” was published in “ACS ES&T Water” (2026, volume 6, issue 5, pages 3153 to 3161). RMIT University is a public research university based in Melbourne, Australia, with programmes in engineering, technology and environmental science. The Water Effective Technology and Tools Research Centre works on treatment methods for water and wastewater. The team highlighted the dual-bubble results in a July 5, 2026 announcement, noting the method’s potential for adoption at existing treatment plants.
Sources: ACS ES&T Water; EurekAlert (RMIT University); Australian Manufacturing
Featured image: photo by Alfo Medeiros on Pexels (free Pexels license).
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I specialize in sustainability education, curriculum co-creation, and early-stage project strategy. At WINSS, I craft articles on sustainability, transformative AI, and related topics. When I’m not writing, you’ll find me chasing the perfect sushi roll, exploring cities around the globe, or unwinding with my dog Puffy — the world’s most loyal sidekick.
