Small-Scale Model Experiments on Plastic Fragment Removal from Water Flows Using Multiple Filters in a Floating Body

Increasing plastic fragments (PFs) in the environment have attracted considerable social and academic attention. Several methods have been proposed to mitigate plastic pollution, such as filtration and degradation. This study focuses on the removal of plastic fragments from a water flow. A field collection survey of beached PFs was conducted at Kurihama Beach (Yokosuka, Kanagawa, Japan) to identify their polymer types and quantify different PFs. An anchored-buoy-type filter was designed to capture surface and submerged PFs from the water flow. A small-scale experimental apparatus was developed with the incorporation of these filters. Four types of filters (steel wire frame, plankton net, reverse osmosis filter, and carbon-block filter) were used as PF removers based on their size. The PF capture experiment was conducted at various PF concentrations, water densities, and flow speeds. The number of captured PFs was calculated using particle counting and mass measurement. The average efficiency of the designed filter was 81.53%, with the efficiency reaching 94.5%. The designed filter was reported to work well in both seawater and freshwater.