Assessment of Microplastics Pollution from Municipal Solid Waste Landfill Sites: A Comparative Study of Controlled and Open Landfills in Bangladesh

Abstract

Microplastics are small plastic particles typically less than 5 mm in size, which originate from the breakdown of larger plastic debris or from microbeads found in consumer products. In the context of landfill sites, microplastics are generated through the degradation of plastic waste due to physical, chemical, and biological processes. Open and controlled landfill sites serve as significant sources of microplastics, where improper waste handling and exposure to environmental elements can exacerbate the fragmentation of plastics. Over time, these particles can accumulate and persist in the environment, posing risks to both terrestrial and aquatic ecosystems. Bangladesh, a country with rapid urbanization and growing plastic consumption, faces significant challenges related to microplastic pollution. The country’s solid waste management infrastructure often struggles to keep pace with the increasing volume of waste, leading to the prevalence of open landfill sites where waste is not adequately contained. Microplastics (MPs) pollution has become an escalating problem in Bangladesh, however data of MPs pollution of landfill sites resources is very limited in Bangladesh. Microplastics in landfill sites in Bangladesh contaminate the local environment and pose long term risks to nearby water bodies, agricultural land, and air quality. Leachate from these landfills often flows into rivers and streams, accumulating microplastics in major waterways throughout the country. This contamination affects aquatic organisms and can enter the food chain, impacting human health. Furthermore, wind dispersion from uncovered landfill sites spreads microplastics into the surrounding soil and air, increasing the potential for human exposure through inhalation and ingestion. Once generated in landfill sites, microplastics can be transported to various ecosystems through leachate flow, wind dispersion, and surface water runoff. The movement of microplastics from landfills to nearby water bodies, soil, and air pathways contributes to their widespread distribution. This transport is influenced by factors such as rainfall, landfill design, proximity to water sources, and the permeability of containment systems. Consequently, microplastics can infiltrate food chains, impact wildlife, and pose potential health risks to humans. This study investigated microplastics pollution in two municipal solid waste (MSW) landfill sites, controlled and open of Dhaka city. In total, 31 samples of different sources were collected from the selected locations of Aminbazar and Kodda Landfill sites. A total of about 1 kg of soil of selected depth was sampled using hand auger, 1 liter of leachate and groundwater was collected from the landfill site, from the connecting river of the landfill site 1 kg of riverbed sediment, 5-10 11 m away from the shoreline was sampled using an Ekman grab sampler (15×15×15 cm) from top 10 cm of the riverbed at each sampling station and lastly, 1 liter of surface water was collected from the water columns Density separation and wet-peroxidation methods were employed to extract microplastic particles. Visual Identification was done using a microscope (OPTIKA v.1.0 2019) at 10 x 40 magnification to identify and quantify the microplastics. Microplastics (MPs) were detected across all sampling locations, with abundances ranging from 15 to 4056 particles per kilogram (kg) or liter (L), depending on the sample type. A total of 18,158 particles were recorded from 31 sampling locations across two landfill sites. The Kodda open landfill site accounted for 7,411 particles across 15 sampling locations, while the Aminbazar controlled landfill site contributed 10,747 particles from 16 locations. At the Aminbazar site, the mean and median MP abundances for soil, leachate, river surface water, riverbed sediment, and groundwater were 900.4 ± 227.9 n/kg and 887 n/kg, 245 ± 85.2 n/kg and 213 n/kg, 188.3 ± 38.2 n/kg and 189 n/kg, 280.2 ± 107.8 n/kg and 341 n/kg, and 48 n/kg for both metrics, respectively. In Kodda, these values were 514.7 ± 115.8 n/kg and 544 n/kg, 362.1 ± 225.8 n/kg and 362.5 n/kg, 360.7 ± 96.6 n/kg and 345 n/kg, 405.3 ± 264.8 n/kg and 457 n/kg, and 514.7 ± 115.8 n/kg and 544 n/kg, respectively. The highest MP abundance was observed in the surface layers of landfill soil due to extensive dumping activities in both older and newer areas, while the lowest was in leachate from the Aminbazar landfill’s treatment facility. At the Aminbazar site, the older landfill soil showed the highest MP concentrations, likely due to prolonged, unmanaged plastic waste accumulation. A decreasing trend in MP abundance with soil depth was noted in both old and new landfill sections, likely attributed to initial deposition at the surface and subsequent weathering and degradation over time. The analysis reveals significant microplastic (MP) pollution across both landfill sites, with higher overall abundance at the controlled Aminbazar landfill compared to the open Kodda landfill. The highest MP concentrations were observed in surface soils, particularly in older landfill sections, highlighting the long-term impact of unmanaged plastic waste disposal. A consistent pattern of decreasing MP abundance with depth was identified, likely due to surface deposition followed by weathering and vertical migration over time. The lowest MP levels were recorded in the leachate of the Aminbazar treatment facility, underscoring the potential effectiveness of controlled landfill management practices in reducing environmental contamination. These findings emphasize the need for improved waste management strategies to mitigate MP pollution and its associated ecological risks.