Solid waste characterization in the slum areas of Bagmati River—A case of Kathmandu, Nepal

Solid waste management (SWM) is a challenging environmental issue globally, with developing nations experiencing considerable difficulties in its efficient and effective implementation. Urban slum areas within these regions, particularly, have been reported to face unique challenges in SWM due to a combination of factors, including the low socio-economic status of residents, high population density, inadequate infrastructure, and a thriving informal economy. Despite these critical concerns, most SWM research in Nepal has concentrated on major cities and tourist hotspots. As a result, the condition of SWM in urban slum areas, typically found along the banks of major rivers in Nepal, remains a critical yet neglected aspect in research and policy discussions. This study, therefore, aims to evaluate SWM in the densely populated urban slum areas situated along the Bagmati River, a key river system in Kathmandu, the capital of Nepal. Four major slum locations within the central metropolitan area of Kathmandu—Sinamangal, Thapathali, Teku, and Balkhu—were selected for the study, and systematic random sampling and characterization of household solid waste was conducted. The results reveal that the average household solid waste generation rates in the four study sites were 155.32 g capita⁻¹ d⁻¹, 124.69 g capita⁻¹ d⁻¹, 149.9 g capita⁻¹ d⁻¹, and 218.44 g capita⁻¹ d⁻¹, respectively. Organic wastes was the most prevalent type, comprising 63.34% of the total waste, followed by paper and paper products (13.72%), plastics (12.15%), dirt and construction debris (5.57%), glass (4.31%), and other wastes (0.91%). Qualitative data from the survey revealed that although municipal waste management programs exist, awareness and participation among residents were limited. As a result, many households ended up managing their waste on their own, often in an unscientific manner polluting the river water in the vicinity. The study offers critical insights for policymakers, operators, and regulators in addressing the growing challenges of SWM. Findings are expected to aid in the sustainable management of solid waste along the river basin in central urban regions of the capital city. Under Nepal's new federal governance system, provincial and local governments are recommended to collaborate with all stakeholders, including households, to develop comprehensive, multimodal SWM strategies that also address the needs of slum areas.