Advances in the Separation and Removal of Microplastics in Water Treatment Processes

Abstract

In this review, we comprehensively analyzed the distribution of microplastics （MPs） in major water ecosystems in China and the fate of MPs during the water treatment process. The removal efficiency of MPs with different colors, sizes, shapes, and materials was also discussed. The results showed that the abundance of microplastics in the aquatic environment was geographically variable and closely related to human activities. Fibrous and transparent （white） microplastics were the most common features in China's water ecosystems and water treatment plants, with polypropylene （PP）, polyethylene （PE）, and polystyrene （PS） being the most common polymer types of microplastics. The removal efficiency of MPs varied from different treatment processes significantly. Pre-treatment and primary treatment in wastewater treatment plants （WWTPs） contributed the most to the removal. In the secondary treatment, the sedimentation tank showed more efficiency than the biological treatment processes. Tertiary treatment processes demonstrated remarkable effectiveness in achieving terminal control of MPs, especially membrane technologies. On the contrary, aeration and hydrodynamic effects may have increased the abundance of MPs in WWTPs. In drinking water treatment plants （DWTPs）, coagulation-sedimentation processes were found to be the most effective in removing MPs, followed by filtration and disinfection processes. Further, both pre-treatment and post-treatment steps also made significant contributions to MPs removal.