Landfill liners as a source of microplastics: Do the guards guard themselves?

Microplastic contamination has received recognition as a significant environmental issue, with its abundance observed in different environments. Landfills, which serve as important storage sites for plastic waste, are known to release large quantities of microplastics through leachate. However, synthetic liners' role as microplastic contributors is poorly known. The study examines the contribution of High-Density Polyethylene (HDPE) geomembrane liners to microplastic concentration in landfill leachate. 1.5 mm thick HDPE geomembrane was subjected to accelerated aging, submerged in synthetic leachate at 23 °C and 50 °C for four months. Physical, mechanical, and chemical tests were conducted monthly for four months to assess the aging process. Electron microscopy was conducted to examine changes in surface features with aging. Each month, after immersion, the synthetic leachate was collected, and filtered, and the residue was analyzed for the presence of microplastics using stereomicroscopy and spectral analysis techniques. The test findings indicated that the HDPE geomembrane liners generated microplastics ranging from 475 to 1689 particles per square meter of the liner material. Higher microplastic (MP) generation was noticed at 50 °C compared to that at 23 °C. Furthermore, most of the microplastic particles were less than 20 μm. The study showed that HDPE geomembrane liners significantly contributed to MP in landfill leachate. Thus, there is a need to search for alternatives with lower environmental impact to be used as landfill liners.