(79a) A Discretization Approach for the Optimal Design of Mass Integration Networks of Eco-Industrial Parks

Environmental pollution is a major concern nowadays because of the adverse impacts it has raised in several aspects such as human health, weather, regional identity, food, security, biodiversity, and economics. Research efforts using process integration strategies have addressed related problems such as the rational use of water in the process industry, in which the minimization of fresh water and wastewater flowrates in single process industries has been considered. The reported methodologies dealing with this line of research can be classified as algorithmic, graphical, algebraic, and mathematical-programming approaches. The reported formulations have considered the implementation of mass integration strategies in single plants. A more global approach consists of taking into account the integration of wastewater from different plants. This strategy provides a relevant incentive since the integration of wastewater from different industries located in the same place could reduce the wastewater discharged to the environment while simultaneously reducing the fresh water usage. In particular, the concept of eco-industrial parks has recently been proposed. An eco-industrial park is a community of manufacturing and service businesses seeking enhanced environmental and economic performance through collaboration in managing environmental and resource issues. As one example, Figure 1 shows how two companies can be integrated into the same industrial zone with processes that share some types of raw materials, inputs, services, products and/or wastes. The goal of this global integration is the benefit of the participating companies considering both economic and environmental aspects. Therefore, an eco-industrial park derives from attempts to apply ecological principles in industrial activities taking into account their interaction with the communities, so that benefits on pollution prevention and sustainable development can be achieved through the cooperation among the organizations. Some papers have recently considered the applicability, modeling and reflections on the implementation, building, management, development, design and planning of eco-industrial parks in specifics countries and/or cities. Another aspect to consider is the mass and energy integration among different processes. This paper presents a mathematical programming model for the mass integration of eco-industrial parks. The model considers the reuse of wastewater among different industries taking into account the constraints given by process sinks and environmental regulations for waste streams discharged to the environment, and allowing the optimal selection of treatment units. The objective function consists in the minimization of the total annual cost including the treatment unit costs, the piping costs and the cost of fresh water. A new discretization approach is proposed for the model reformulation to handle the bilinear terms of the model as part of a global optimization strategy. The application of the proposed model shows some of the incentives for the integration of industries within an eco-industrial park framework with respect to the individual integration of each industry.