RESUMO
A multi-stage optimization approach for sustainable collection system design for urban municipal solid waste is developed for megacities in Asia's newly industrialized countries. The approach combines four methods-analysis of waste and area characteristics, data acquisition and evaluation by GIS, mathematical projection of existing and future collection systems, and identification of most suitable alternatives through comparative multi-criteria decision analysis (MCDA). The approach is applied in Bangalore, India with 1.66 million inhabitants and 46.7-km2 area of investigation, and stratified based on population density. Two possible collection mechanisms (door-to-door (D2D) and community bin (CB)) are analyzed with a varied combination of collection coverage and waste segregation level. The study results confirm that both operational and investment expenses of the collection system decrease with an increasing rate of CB collection. Moreover, overall CO2 emissions of waste collection from the entire area of investigation decrease from 5.2 to 3.1 tons per day if the present 100% D2D collection is replaced with 100% CB collection system. Also, the increase of segregation at source contributes to the reduction of operational expenses and CO2 emissions; for example, a 20% increase of segregation level for D2D collection system leads to a 6% reduction of CO2 emissions. Considering all decision parameters through MCDA, a collection system comprising only CB with one separate compartment for wet waste and another combined compartment for dry and mixed waste is determined to be the most favorable approach.