Microplastics in landfill leachate and its treatment

Landfill leachate is a prominent source for microplastics into the environment. Various polymer types have been detected in leachate collected from landfills and among those polyethylene and polypropylene were the most prominently detected polymer types, with a size ranged from 20 to 5,000 μm. Fibers, foams, films, beads, and fragments were the mostly detected shapes, and a majority was transparent and yellow colored. The abundance of microplastics in leachate varied with the type of waste present in landfills. Microplastics present in leachate migrated to the surrounding soil, groundwater, and open waters located nearby landfills. The main migration pathways are direct leaching and usage of treated leachate as a soil conditioner, and usage of microplastic-contaminated sludge released from leachate-treatment facilities as fertilizers. To reduce the risks associated with microplastics released from landfill leachate, treatment of landfill leachate using proper treatment strategies is mandatory. The main techniques used to remove microplastics from landfill leachate are physical, chemical, biological, and land-based processes. After the treatment, abundance, size, and chemical composition of microplastics were altered considerably. However, the complexity and composition of leachate decreased the efficiency of treatment techniques substantially. This chapter provides a descriptive overview of the occurrence, abundance, and properties of microplastics extracted from leachate, the main migration pathways that reintroduce microplastics into the surrounding environment, the main treatment techniques, and challenges associated with the treatment strategies.