A robust optimization model for the location of municipal solid waste landfills

One of the issues facing urban communities is waste management. In this paper, we determine the location of landfills, the capacity of these sites, the location of transfer stations, their capacity, and the location of waste recycling centers in such a way that the total costs (including the costs of establishment and transportation of waste from production to refining sites, landfills and recycling centers) are minimized. We also control pollution levels by defining a maximum allowable pollution for each population center to comply with environmental constraints. In this study, the problem is formulated as a mixed integer programming model. Then, the capacity of the landfill and the capacity of the refining sites are considered as uncertain parameters and a robust optimization model is developed. Also, to validate the model, a problem instance is solved and the computational results are presented for different levels of conservatism. The decision maker can use the results to select the appropriate level of conservatism.