Occurrence and Characteristics of Microplastics in a Wastewater Treatment Plant

Large quantities of microplastics (MPs) are discharged into the hydrosphere via the municipal wastewater treatment plant (WWTP) as an important route. Herein, we sampled the influent, effluent and sludge of WWTP in order to investigate the abundance, size, type, and shape of MPs. The detected MPs were primarily in the shape of fiber with the abundance up to 44 particles per liter. Polyethylene terephthalate, polypropylene, and polyethylene were found to be the three largest types of MPs. MPs in the influent was effectively eliminated with a removal efficiency of ~ 96%. However, a large quantity of MPs was still discharged in the effluent and the excess sludge, approximately 2.87 × 10⁸ particles per day, indicating that some specific control facilities should be installed at WWTP to minimize the environmental impacts of MPs.