Life cycle assessment as a decision-making tool for the design of urban solid waste pre-collection and collection/transport systems

This paper compares the environmental performance of different municipal waste pre-collection and collection/transport systems, using the life cycle assessment methodology. The scenarios compared consider conventional containerisation systems, underground containerisation and pneumatic collection/transport systems. The results show that pneumatic systems have a greater impact on climate change, acidification, particulate matter and stratospheric ozone depletion due to their significant electricity consumption and the environmental impact of pipelines manufacture. However, in relation to terrestrial eutrophication and photochemical ozone formation, underground containers exhibit a greater impact. A general sensitivity analysis was carried out, for all of the scenarios analysed, and a specific one for the pneumatic scenario. Results show that the environmental impact of pneumatic systems and underground containerization is higher than that of conventional systems. These results are completely determined by the consumption of materials (in the two cases) and energy (for pneumatic scenario). This environmental conclusion has to be taken into account for policy making in urban areas, along with other social and economic aspects. In terms of climate change, the comparison allows us to conclude that pneumatic systems have a carbon footprint 119% higher than the lowest impact scenario (side-loading containers located in drop-off-points). Among the conventional pre-collection and collection/transport scenarios, the one with the greatest carbon footprint is the one that uses underground containers; 16% higher than the scenario with side-loading containers located at drop-off-points. Among the scenarios that use conventional containers on the surface, the door-to-door scenario has the greatest impact.