A proposal of an economic optimization model for sustainable waste management

When planning sustainable waste management systems (WMSs), decision makers should consider various aspects, including environmental, economic and social issues. In this framework, a linear programming model may be useful to identify the best scenario among the many theoretically possible. With reference to previous research by the same authors on environmental optimization, this paper focuses on the economic optimization of WMSs. Various mathematical models, generally complex and difficult to solve, have been proposed for the analysis of municipal solid WMSs. This study proposes a model structured according to the transportation problem and which involves an economic interpretation of the dual problem. This simple formulation of the problem allows a rapid estimated solution of the real problem. The proposed model was tested in a hypothetical, although realistic, context, by considering four different waste sources, five waste fractions and six potential destinations, with and without more restrictive constraints. Through an economic interpretation of the dual problem, which has not been considered in the literature until now for this topic, decision makers can decide whether outsourcing the waste management or receiving a certain amount of waste to handle/dispose of. The results show the usefulness of this model for strategic decisions, such as in the case of plant siting. A limitation of the proposed model is that it does not take into account some important aspects, such as economies of scale. It is certainly useful in the short term and needs to be applied systematically over time and at small time intervals.