A triple-bottom-line evaluation of municipal solid waste collection

Abstract

Municipal Solid Waste (MSW) collection systems can contribute to a sustainable society by transforming waste to valuable resources. However, if not properly designed, the MSW collection systems can become a liability in terms of high cost, high emissions and reduced service. There is still a lack of knowledge on how MSW collection system designs trade off the elements in the triple bottom line. The purpose of this study is to contribute to such understanding. A service-mix framework is proposed, demonstrating trade-offs among the decision areas of bin types, vehicle types, pick-up frequency, delivery distance, co-collection, and sorting in MSW collection systems. The triple bottom line performance is evaluated on cost, service, and emission levels. Two MSW collection systems are analysed and compared, using an Excel-based spreadsheet model. The findings show a potential to improve sustainability in MSW collection systems by trading off service-mix components. Specifically, the findings show that if five households share bins (accept reduced convenience, and the data indicate that they do) the reduction potential is 46 % for cost and 27 % for the CO₂ emissions. Similarly, reducing the pick-up frequency service reduces cost and CO₂ emissions. Finally, a sensitivity analysis of fill rates shows that using dual chamber trucks gives a high risk of increased cost and CO₂ emissions, due to the difficulty of matching waste volumes and chamber sizes. Thus, the paper demonstrates that significant reduction of cost and emission levels are possible without a significant sacrifice of service levels in MSW collection systems.