Technical, economic and environmental analysis of a MSW kerbside separate collection system applied to small communities

摘要

The main aim of this study was to evaluate the costs and environmental impacts induced by a fixed model of MSW kerbside separate collection system for communities up to 10,000 inhabitants, in order to evaluate the convenience for the smaller municipalities to unite and form more economically and environmentally sound systems. This topic is important not only due to the large number of small municipalities (e.g. in Italy 72% of the municipalities has less than 5000 inhabitants) but also to the fact that separate collection systems are typically designed to take into account only the technical and economic aspects, which is a practice but not acceptable in the light of the sustainable development paradigm. In economic terms, between 1000 and 4000 inhabitants, the annual per capita cost for vehicles and personnel decreased, with a maximum at approximately 180 e/inhabitants/year; while, from 5000 up to 10,000 inhabitants, the annual per capita cost was practically constant and equal to about 80 €/inhabitants/year. For the municipalities of less than 5000 inhabitants, from an economic point of view the aggregation is always advantageous. The environmental impacts were calculated by means of the Life Cycle Assessment tool SimaPro 7.1, while the economic-environmental convenience was evaluated by combining in a simple multicriteria analysis, the annual total per capita cost (e/inhabitants/year) and the annual total per capita environmental impact (kEco-indicator point/inhabitants/year), giving the same importance to each criteria. The analysis was performed by means of the Paired Comparison Technique using the Simple Additive Weighting method. The economic and environmental convenience of the aggregation diminishes with the size of the municipalities: for less than 4000 inhabitants, the aggregation was almost always advantageous (91.7%); while, for more than or equal to 5000 inhabitants, the aggregation was convenient only in 33.3% of the cases. On the whole, out of 45 cases examined, for the municipalities from 1000 to 9000 inhabitants, the aggregation was both economically and environmentally convenient in 60.0% of the cases.