Integrating Material Flow Analysis into Solid Waste Management System in Medan City, Indonesia

Material flow analysis (MFA) is a quantitative and structured method for analyzing systems by identifying material flows, losses, and accumulation within a system. This study aims to integrate MFA into the existing solid-waste management system in Medan to establish a mass-balanced, city-level MFA of Medan in 2023. The functional unit is tons of solid waste per year. The analysis covered waste generation, collection, recovery, final disposal, and stock accumulation, and integrated both the formal sector (local-government collection, transfer depots, waste banks, and the TPS 3 R facility) and the informal sector (small- and large-scale waste collectors, scavengers, and recycling industries). The data were collected through field observations, in-depth stakeholder interviews, local government reports, official facility inventory data, transportation logs, literature-derived coefficients, and were reconciled in STAN. Of an estimated 632,149.41 tons/year of waste generated in Medan, approximately 84.66 percent entered a collection pathway and remained as uncollected waste. Landfill inflow to Terjun landfill reached 466,098.09 tons/year (73.73 percent), while 391,918.06 tons/year (62.00 percent) accumulated as waste stock. Further, 25,496.63 tons/year (4.03 percent) were directed to waste banks, 537.80 tons/year (0.09 percent) to TPS 3R, and 53,403.20 tons/year (8.45 percent) to the recycling industry, whereas the uncollected waste reached 114,919.19 tons/year (18.18 percent). The study contributes the city-level MFA for solid-waste management in Medan that integrates formal and informal sectors using operational data and an embedded uncertainty analysis, providing a quantitative baseline that Medan previously lacked. These findings provide quantitative insights to support policymakers in improving sustainable solid-waste management in Medan.