Waste flow analysis and life cycle assessment of integrated waste management systems as planning tools: Application to optimise the system of the City of Bologna

Abstract

The results of this case study are used to argue that waste management planning should follow a detailed process, adequately confronting the complexity of the waste management problems and the specificity of each urban area and of regional/national situations. To support the development or completion of integrated waste management systems, this article proposes a planning method based on: (1) the detailed analysis of waste flows and (2) the application of a life cycle assessment to compare alternative scenarios and optimise solutions. The evolution of the City of Bologna waste management system is used to show how this approach can be applied to assess which elements improve environmental performance. The assessment of the contribution of each waste management phase in the Bologna integrated waste management system has proven that the changes applied from 2013 to 2017 result in a significant improvement of the environmental performance mainly as a consequence of the optimised integration between materials and energy recovery: Global Warming Potential at 100 years (GWP100) diminishes from 21,949 to −11,169 t CO₂-eq y^-1 and abiotic resources depletion from −403 to −520 t antimony-eq. y^-1. This study analyses at great detail the collection phase. Outcomes provide specific operational recommendations to policy makers, showing the: (a) relevance of the choice of the materials forming the bags for ‘door to door’ collection (for non-recycled low-density polyethylene bags 22 kg CO₂-eq (tonne of waste)^-1); (b) relatively low environmental impacts associated with underground tanks (3.9 kg CO₂-eq (tonne of waste)^-1); (c) relatively low impact of big street containers with respect to plastic bags (2.6 kg CO₂-eq. (tonne of waste)^-1).