Selected unit processes in microplastics removal from water and wastewater

The objective of the research study was to evaluate removal efficiencies of polyester fibers, polyvinyl chloride (PVC) granules, acetonitrile-polyester fibers, polypropylene fibers, foil fragments, and personal care products fragments during sedimentation and coagulation under laboratory conditions. The effect of oil and cellulose fibers presence was also evaluated. Most of the microplastics used during the studies did not settle down under the gravity force. Only a small part of polyester fibers (about 6%) settled down during 2 h of the experiment. Oil presence in samples had an important effect on the behavior of all kinds of microplastics particles. Oil spots have trapped microplastics fibers, powder, and fragments. The presence of cellulose fibers in the water had no significant effect on microplastics removal. The slightly higher removal efficiency was observed when the cellulose fibers were soaked with oil. The coagulation process was effective in the removal of two kinds of microplastic particles: polyester fibers (84%-89% removal efficiency) and PVC powder (20% removal efficiency). The main parameter which affected coagulation was the presence of oils. In the presence of oil huge part of microplastics was trapped in the spots and did not undergo coagulation.