Optimization modelling for industrial waste reduction planning

Abstract

A model is developed for planning the implementation of industrial waste reduction and waste management strategies. The model is based on minimizing the overall cost of waste reduction and waste management for an industrial facility over a certain time period. The problem is formulated as a general mixed integer linear programming (MILP) problem, where the objective function includes capital and operating costs and is subject to a number of constraints that define the system under consideration. The information required to use the modeling approach includes the capital and operating costs of the various optios being considered, discount rates, escalation factors, the capacity limitations on various options for waste treatment, disposal and management, as well as treatment efficiencies and the potential for waste reduction. The general modeling approach is applied to a case study facility. The MILP formulation was solved using a commercially available software package. The model could be used by an environmental engineer or a planner in an industry that is considering implementing waste reduction projects. Ideally, the industry would have generated information on modifications that could reduce their waste generation, as well as information on their current waste management practices. In the event that specific waste reduction projects have not been identified, the economic feasibility of potential future projects could be determined. In using the model, an intermediate to long-term perspective is preferred. The modeling approach is limited to an economic analysis, with technical and policy considerations included in the constraints. This approach is meant to be used within a context where consideration is given to other factors (e.g., environmental, political, social, legislative) that must be accounted for in the decision-making process. In this way, the model is meant to be used as a tool in an overall decision-making framework. The potential usefulness of the model is that it allows consideration of the economic realities and budgetary constraints of an industry, while maintaining a long-term perspective that will encourage the implementation of waste reduction initiatives.