Coexistence of microplastic particles and heavy metals in landfill leachate: A case study of a landfill in Indonesia

Landfill leachate is a known source of environmental contaminants, including microplastics and heavy metals, which pose significant risks to ecosystems and human health. This study investigates the presence of microplastics and their associated heavy metals in leachate from the Piyungan landfill in Yogyakarta, Indonesia. Sample preparations included wet peroxide oxidation and density separation using a saturated sodium chloride solution. The analysis of microplastics was performed using an optical microscopy and an Attenuated-Total Reflectance Fourier Transform Infrared (ATR-FTIR) spectroscopy. Heavy metals' concentration in leachate and microplastics was quantified using Atomic Absorption Spectroscopy (AAS). The abundance of microplastics in leachate ranged from 2100 ± 1301 to 4385 ± 1350 particles/L, with older landfill leachate exhibiting higher concentrations of microplastics. The dominant forms of microplastics are black fragments and films. The detected polymers include high-density polyethylene (HDPE), polypropylene (PP), and polyamide polymers. With zinc being the most prevalent heavy metal, followed by Pb, Cr, Cu, and Cd, the concentration of heavy metals in the leachate dramatically decreased following the leachate treatment. Zn, Cu, and Cd enrichment was significant on the identified microplastics, but not for Pb and Cr. The attachment of heavy metals onto microplastics was influenced by many factors, including the heavy metal concentration. Zn showed the highest accumulation on microplastic particles. This study highlights the potential of some toxic heavy metals to accumulate on microplastic particles and to co-transport from landfill leachate to surrounding ecosystems. Thus, the improved landfill treatment technologies and strategies to mitigate the environmental impact of microplastic-heavy metal interactions are necessary. • The Piyungan landfill leachate contains a significant amount of microplastics and heavy metals. • Zn, Cu, Cd are enriched on the surface of microplastics found in the Piyungan landfill. • Heavy metal enrichment on microplastic facilitates the co-transport of heavy metals to surrounding environment. • Microplastics-heavy metal pollution must be mitigated by better landfill leachate treatment and technologies.