Migration and Removal of Microplastics in a Dual-Cone Mini-Hydrocyclone

In this study, we analyzed the migration and removal of microplastics (MPs) using a dual-cone mini-hydrocyclone, thereby addressing the research gaps in flow mechanisms and separation efficiency for low-density MPs. We constructed and experimentally verified a numerical model. We discussed the velocity distribution of the flow field and the effects of the feed flow rate, feed MP volume fraction, and density on the distribution of MPs. The flow field analysis demonstrated maximum axial velocity at the cylindrical axis and peak tangential/radial velocities in the large cone section, promoting MP enrichment along the axis. The separation efficiency was improved with higher feed flow rates (e.g., 78.56% at 10 m/s for 50 μm MPs) but decreased with an increase in the MP volume fraction due to particle collisions. The MPs with densities below water demonstrated near-complete separation (98.51%), whereas those larger than water density exhibited minimal efficiency. The MPs are concentrated in the large and small cone axes, with density differences that significantly affect the migration patterns.