Advanced nanobubble flotation for enhanced removal of sub-10 µm microplastics from wastewater
Sub-10 µm microplastics (MPs) in aquatic environments pose significant
ecological and health risks due to their mobility and potential to carry harmful
microcontaminants. Our effluent analysis from a Hong Kong Sewage
Treatment Works shows that traditional treatment often fails to effectively
remove these MPs. These small-sized MPs are commonly neglected due
to challenges in accurate quantification, analysis, and removal. This study
introduces a nanobubble-assisted flotation process that enhances the
removal efficiency of both regular and irregular small-sized MPs from
wastewater. The proposed process outperforms the traditional flotation process
by fostering a more effective interaction between bubbles and MPs, increasing
removal rates of MPs from 1 µm to 10 µm by up to 12% and providing a total
efficiency boost of up to 17% for various particle sizes. Improvements are
attributed to enhanced collision and adhesion probabilities, hydrophobic
interactions, as well as better floc flotation. Supported by empirical evidence,
mathematical models, and Molecular Dynamics simulations, this research
elucidates the nanoscale mechanisms at play. The findings confirm the
nanobubble-assisted flotation technique as an innovative and practical
approach to removing sub-10 µm MPs in water treatment processes.
