INTEGRATED SOLID WASTE MANAGEMENT: A MULTICRITERIA APPROACH

The paper presents the first results of a long term research aimed at producing a decision support system to deal with the integrated solid waste management planning at regional level. In the last years urban waste management has received a strong attention from the public authority in Italy culminating in a new national law, which has priorities such as waste prevention (waste avoidance and reduction) reuse and recycling. Italian Legislation requires to consider not only a series of waste management options aimed at source reduction but also to integrate the environmental soundness with economical viability and social equity. To support this integrated solid waste management it is necessary to ascertain the environmental, economic and social impacts associated with various waste management options so that decision makers can trade them off to achieve a better waste management strategy. To deal with the problem a three level process is suggested: zoning of the territory, implementation of the waste plan, Environmental Impact Assessment (EIA) on the new facilities. The paper focuses, in a non technical way, on a dynamic mixed integer linear programming model to be used in the second phase of the previous process. A multicriteria approach has been adopted to manage waste as an integrated system of recollection, transportation, recovery and disposal activities. At the moment four objective functions have been defined: total cumulative distance, total discounted net cost, total cumulative impact on traffic due to waste transportation, total cumulative landfilling. The model includes different types of collection, as well as different technologies. The model gives the possibility to locate in the same site more facilities. In this way it is possible to construct waste integrated platforms which permit to reduce costs and impacts. The model chooses the sites to be developed, the types of technology that will be installed on such sites, and the schedule of activity. In accordance with the input concentration for each technology it is possible to specify the appropriate output coefficients. The model computes the yields of the intermediate technologies directly from the model parameters, such parameters are exogenously determined, case by case, on the basis of the technical information; all the yields are automatically recomputed by the model when they vary. In this way high flexibility is introduced into the model. According to the preference of the decision maker specific constraints can be introduced in order to limit the admitted technologies; such restrictions have yearly validity. In this way a good representation of a dynamic situation can be reached. The main aspects that can be studied in space and time are: waste recollection at municipality, destination of each type of waste, technologies operating at facilities, landfilling, material and energy recovering, cost, traffic impact due to waste transportation. The results of a first application referred to the Province of Ravenna, in Emilia Romagna Region, Northern Italy are presented in the final section.