Microplastics in a solid waste landfill in Japan: concentrations in landfilled waste, cover soil, rainwater and leachate

Microplastics (MPs) have become a major environmental concern due to their persistence and potential impact on ecosystems. It is essential to understand the behavior of MPs in landfill sites to effectively manage waste and protect the environment. This study aims to investigate the behavior of MPs in a solid waste landfill site, Japan, as a case study and assess their potential sources, distribution, and environmental implications. In the targeted landfill site, microplastics (MPs) were detected in the intermediate cover soil and final cover soil, and it has been confirmed that the MPs found in intermediate cover soil originate from crushed incombustibles generated at the crushing-sorting plant. This confirmation is based on the similarity in representative components. In the rainwater reservoirs, although only a small amount of MPs was found in the surface water, a significant number of MPs were found in the sediments. Substantial quantities of MPs were identified in samples taken from the landfill site. In contrast, very few MPs were detected in raw leachate and none were found in the treated leachate at the leachate treatment facility. This suggests that treatment process is effective in removing MPs.