Behaviors and emission inventories of microplastics from various municipal solid waste incinerators in Japan

We explored the microplastic (MPs) emissions of Japanese municipal solid waste incinerators (MSWIs); specifically, the numbers and types of MPs in wastewaters discharged by three MSWIs. We calculated the MSWI MPs emission factors and inventories, and we discuss the results. More than fifteen types of MPs, principally fragments shape were detected. It was important to obtain composite samples because the nature of raw wastewater fluctuated significantly during both day and night in response to the MSWI treatments. MSWI wastewater treatments tended to remove larger particles; over 99% of MPs (in terms of both number and weight) were ultimately removed. The MP emission inventory from MSWIs to public water bodies was 7.22 × 10⁵–1.64 × 10⁶ MPs/year for MPs sized 100–5000 µm. This is very low, at only 0.0053–0.026% of the total MP emission inventory Japanese WWTPs. It is, therefore, possible to remove almost 100% plastics in input waste via incineration and wastewater treatment.