High-throughput processing of microplastics based on Z-type radial flow separator: Fluid flow characteristics

In present study, an innovative Z-type radial flow separator (ZRS) was developed to address the limitations of traditional axial flow rapid sand filters, including small filtration area, large bed pressure drop, and instability of high-throughput flow. The device reconstructs the dynamic characteristics of the flow field through the guide cone structure, and synergizes with the adsorption mechanism of activated alumina to enable the efficient transformation from axial flow to radial-spiral composite flow state, which significantly enhances the high-throughput and deep separation performance for microplastics (MPs). The pilot experiment of 5 m³ /h demonstrated that the Type-D configuration resulted in a 62.4 % lower maximum pressure drop amplitude compared to the benchmark Type-A, and MPs distribution inhomogeneity was reduced by 63.1 %. For MPs with particle sizes both below and above 10 μm, the separation efficiencies for Type-D were 87.65 % and 86.4 %, respectively, increasing by 10.87 % and 16.93 % over the axial flow mode. In a wide feed concentration range of 10-200 mg/L, Type-D achieved stable rejection of 1-20 μm MPs, with especially high performance at low concentrations of 10-20 mg/L, the removal efficiency reached 92-96 %. This study confirmed that ZRS has substantial potential for application in the tertiary treatment process of wastewater treatment plants.