Un integrated model for reverse logistics and sustainability in waste management

The problem of waste reduction and recycling is a critical issue in environmental sustainability and in the development of sustainable cities and countries. This makes increasingly urgent to reduce the fractions for disposal and to reduce the problem of depletion of resources, by the employment of raw materials, resulting from industrial and civil wastes, in other production processes. Some factors such as the quality of waste collection and the collection rate enable high levels of recycling and reuse of materials at the end of life (paper, plastic, glass, and aluminium), the production of high quality compost from the wet fraction, and of fuel with high calorific value from the dry fraction. In this context, the collection of municipal solid waste can be a discriminating element in the definition of the performance level of waste reverse cycle process, both in terms of quality of obtained products and impact on the environment. As a consequence it significantly affects the cost of waste management. This paper analyzes and develops an original planning model for waste collection system based on an integrated “kerbside” system, which is applied by many Italian municipalities, as an alternative to the traditional collection of garbage bins “on the road”. Critical topics as the modelling of the collection network and its routing, the sizing of vehicles and teams required to collection service and the optimal allocation of recovery plants are discussed. Some heuristic algorithms are developed and have been applied to a case study. From this some alternatives based on “kerbside” collection systems are evaluated and compared from logistical and economic points of view. Finally the environmental impact assessment carried out by the Life Cycle Assessment (LCA) methodology, provides an additional tool to compare the sustainability of different waste collection services, including the traditional collection of bins “on the road”.