Evaluation of operational,economic,and environmental performance of mixed and selective collection of municipal solid waste: Porto case study

Abstract

This article describes an accurate methodology for an operational, economic, and environmental assessment of municipal solid waste collection. The proposed methodological tool uses key performance indicators to evaluate independent operational and economic efficiency and performance of municipal solid waste collection practices. These key performance indicators are then used in life cycle inventories and life cycle impact assessment. Finally, the life cycle assessment environmental profiles provide the environmental assessment.

We also report a successful application of this tool through a case study in the Portuguese city of Porto. Preliminary results demonstrate the applicability of the methodological tool to real cases. Some of the findings focus a significant difference between average mixed and selective collection effective distance (2.14 km t^-1; 16.12 km t^-1), fuel consumption (3.96 L t^-1; 15.37 L t^-1), crew productivity (0.98 t h^-1 worker^-1; 0.23 t h^-1 worker^-1), cost (45.90 € t^-1; 241.20 € t^-1), and global warming impact (19.95 kg CO_2eq t^-1; 57.47 kg CO_2eq t^-1).

Preliminary results consistently indicate: (a) higher global performance of mixed collection as compared with selective collection; (b) dependency of collection performance, even in urban areas, on the waste generation rate and density; (c) the decline of selective collection performances with decreasing source-separated material density and recycling collection rate; and (d) that the main threats to collection route efficiency are the extensive collection distances, high fuel consumption vehicles, and reduced crew productivity.