Waste characterization as a pathway to circular resource management in Karachi’s district east

Karachi, Pakistan’s largest metropolitan hub, produces more than 12,000 tons of municipal solid waste (MSW) daily, presenting substantial environmental and operational challenges. This study focuses on District East, one of the most populous and urbanized districts by examining its MSW characteristics, daily operational trends, and material recovery potential. The research involved field-level waste sampling at GTS Imtiaz and three supplementary sites (Purani Sabzi Mandi, NIPA, and Bahadurabad), applying ASTM D5231-92 protocols for manual sorting and ASTM D3174-07 for proximate analysis. Furthermore, elemental analysis was conducted to determine carbon, nitrogen, and sulfur composition. The study recorded daily waste flows at GTS Imtiaz throughout January 2023, accounting for 8289 trips and 44,532 tons of waste. Proximate analysis revealed that organic waste consistently exhibited high moisture content (> 50%) while heterogeneous waste showed significant volatile solids. Elemental analysis highlighted a carbon content of up to 55.1% in wood waste and nitrogen content exceeding 1.4% in organic waste, suggesting its suitability for composting and bioenergy applications. Heterogeneous waste fractions demonstrated calorific values of up to 4,232 kcal/kg, reinforcing their energy recovery potential. These insights emphasize the value of integrating localized composting initiatives and selective RDF (Refuse-Derived Fuel) strategies to alleviate landfill dependency. The findings aim to support Karachi’s waste authorities and urban planners in developing decentralized and sustainable MSWM models that are responsive to local spatial, demographic, and waste stream variations.