Enhanced microplastic separation via microbubble-assisted mini-hydrocyclone

Microplastics (MPs) are widespread in aquatic environments and pose health risks by absorbing toxins and entering the food chain. Therefore, effective removal strategies are urgently needed. Mini-hydrocyclones (MHCs) offer a promising solution due to high throughput, fast processing, and low maintenance. However, their efficiency decreases when MPs have densities close to water. To address this, microbubbles (MBs) have been introduced to reduce MPs’ apparent density and enhance separation. Still, studies on MB–MP interactions in the complex centrifugal flow of MHCs are limited, requiring further research.

This study examines MP separation under various flow rates, MB concentrations, and surface charge conditions. Overflow visualization confirmed strong MB–MP attachment, even with short residence time. High-speed visualization revealed that stable air core formation is key to effective separation. Under optimal conditions, MBs enhanced removal efficiency by up to 34%. However, excessive MB concentration or low flow rate led to unstable air cores and reduced performance. These findings improve understanding of MB-assisted mechanisms and help define practical operating conditions. The results also highlight the strong potential of MHCs as efficient, low-maintenance solutions for decentralized water treatment, especially in remote or small-scale applications.