Deciphering the connection between the informal plastic recycling industry and the microplastic pollution in the Buriganga River

Abstract

Microplastic pollution poses a significant global threat to ecosystems and human health, yet limited research exists in underdeveloped regions such as Bangladesh. This study investigates microplastic contamination in the Buriganga River, Dhaka, focusing on the impact of the nearby plastic recycling industry. Five different sites on the bank were selected to collect water and sediment samples. The microplastic particles from these samples were separated by density separation and filtration. The particles were photographed under a microscope to obtain length and surface area data by analyzing the microscope images. Shapes were obtained from the microscope images dividing all the particles into three types of shapes: fragment, filament, and fiber, with fragments being the most plentiful. Raman spectroscopy was used to identify the microplastic particles, and polystyrene was found to be abundant. Quantification of these particles showed the intense effect of the recycling industry, with particle counts thousands of times higher than those at the other sites. Most of the particles (53.6% in water and 68.7% in sediment) identified were 1–5 mm in size. The most abundant shape of particles was fragment in both water (67.9%) and sediment samples (85.8%), followed by fiber in water (19.6%) and filament in sediment (13.9%). Polypropylene (48%) and polystyrene (68%) were the most abundant types of plastics in water and sediment, respectively. Polyethylene was also identified in both water (24.5%) and sediment (10.2%). Downstream sites exhibit elevated microplastic levels, likely influenced by the recycling zone, while upstream sites, despite having less external activity, still show substantial microplastic contamination, indicating a complex interplay of factors contributing to river pollution. This study highlights the urgent need for improved waste management and targeted regulatory interventions on unregulated plastic recycling industries to mitigate microplastic pollution in urban rivers.