Identification of Optimal Urban Solid Waste Flow Schemes under Impacts of Energy Prices

A large number of interval linear programming models were developed for urban solid waste management under uncertainty. Nevertheless, few of them can address the possible effects of energy prices on the identified waste management policies. This study proposes a fuzzy interval semi-infinite programming model by introducing the concept of a functional interval into the waste management problem. The model is applied to a case study and compared to the existing fuzzy interval linear programming (FILP) and interval semi-infinite programming (ISIP) models to illustrate the differences in producing associated waste management polices. Results reveal that the energy prices do have impacts on the optimal waste flow patterns, net system benefit, and satisfactory degree. In contrast to FILP, the FISIP model can produce a policy with low risk of system failure (or high satisfactory degree), and has better adaptability to the energy price fluctuations. In addition, the FISIP model has the advantages over the ISIP model in that it can (1) simultaneously deal with multiple types of parameter uncertainties, (2) allow for the existence of tolerance intervals for each of the constraints, (3) reflect what extent the constrains would not be violated, and (4) provide flexible patterns for cost-effectively transporting the urban solid waste.