A multi-approach model to optimize municipal solid waste management: an application to an Italian metropolitan area

In the last decade, people concerns and regulations pressure have made sustainability and waste management key topics both in political and companies agendas. The European Commission (EC) with its new Directive on waste (2008/98/CE) has set as a main goal for every Member State government to radically minimize the negative environmental impacts from producing and managing waste. Thus, the aim is to facilitate and promote the differentiated waste collection starting from local municipalities, in order to strongly increase the percentage of waste that can be recovered and recycled. Although at international level some organizational models have been proposed, they are not extensively applicable because of peculiarities in each country. Moreover, most of these models are focused on manufactures or final users rather than on municipalities. Literature does not present many reference models to support these critical actors in their strategic decisions. In particular, there seem not to be any models which can deal simultaneously with operating cost, legislative targets and the way these elements vary in function of waste quality and efficiency of the reverse logistics system. Therefore, objective of this paper is to introduce a model which supports the decision making process in designing a reverse system for Municipality Solid Waste Management (MSWM). Specifically, the model aims to determine which sites (selection, processing and disposal facilities) needs to be opened and the optimal waste quantity - per each collection alternatives (i.e. diversified or undiversified) - to be sent through different sites, taking into account transportation and processing cost on top of the targets imposed by current legislation. A genetic optimization algorithm is adopted to solve the model. Then, a validation has been performed using a data set representing a real municipality operating in a large metropolitan area in Italy.