Abstract:
In developing countries like Bangladesh, waste management faces significant challenges, including low collection coverage, inadequate transport services, and insufficient treatment facilities, leading to widespread pollution. Dhaka, the capital of Bangladesh, generates a substantial amount of solid waste daily, approximately 6756 tons, managed by two disposal sites. The Amin Bazar site, 17 km west of DNCC headquarters (Gulshan-2), handles solid waste for Dhaka North City Corporation. Despite concerns about soil and water contamination due to poorly managed landfills, studies investigating such contamination, especially at Amin Bazar, still need to be included. This study aims to fill this gap by examining potential soil and water contamination near the disposal site. A comprehensive study assessed soil and water contamination near the Amin Bazar disposal site, collecting samples from various sources during dry and monsoon seasons. The analysis included soil contaminants, treated leachate performance evaluation, and in-depth investigations through boreholes and monitoring wells. The Leachate Pollution Index (LPI) was calculated to understand the combined health impact, contributing to a comprehensive understanding of the landfill's environmental impact.
Analysis of inland surface water on the south side reveals heightened levels of contaminants, with an LPI of 12.44, attributed to open dumping practices. During both dry and monsoon seasons, inland surface water bodies and nearby river water exhibit critically low dissolved oxygen levels, posing risks to aquatic life. Soil data within 450 meters of the disposal site shows significantly higher organic content, especially within the south side of the disposal site, and elevated heavy metal concentrations, surpassing USEPA guidelines. Among all heavy metals, the higher value of Lead (Pb) is found in surface water, groundwater, and soil samples.
Monitoring well analysis results confirm groundwater contamination, and borehole data highlights increased heavy metal levels. The treated leachate satisfies Solid Waste Management (SWM) Rule 2021 standards, and during the monsoon season, lower concentrations were observed, attributed to rainwater dilution and mixing with river water. Treated leachate meets standards, with lower concentrations during the monsoon attributed to dilution. However, LPI values indicate a significant environmental impact, especially on the south side, suggesting potential contamination. Despite groundwater parameters complying with standard limits except Pb, elevated Health Risk Index (HRI) values for arsenic in groundwater samples indicate a potential health risk, emphasizing urgent waste management and environmental preservation interventions.