Water Networks for Eco-Industrial Parks with Optimal Trade-offs between Economic and Environmental Aspects

Integration of water-using units in eco-industrial parks (EIPs) has been widely studied to achieve a sustainable and circular economy. Most studies focus on minimizing the cost and maximizing the utilization of the interplant water. In this study, the environmental impact of the water network is incorporated into its design and contrasted with the water network cost. A mixed-integer linear programming (MILP) model is proposed to design the water networks with the following objectives: total economic cost (EC) and environmental impact (EI). The model facilitates designing an intertreatment unit network based on concentration limits to extract maximum benefits from the available treatment facilities. The developed method was tested in two case studies of varying capacities. The minimum EC and EI networks realized at least 13.83 and 8.31% reduction in cost and pollutant discharge, respectively, compared to the minimum freshwater network. It was observed that the lowest EC network discharges higher quantities of pollutants by about 32.73% whereas the lowest EI network incurs 12.25% higher cost on average. Thus, trade-off solutions (Pareto) between the competing objectives were generated by using the augmented ε-constraint (AUGMECON) method for further analysis. Finally, the reduction achieved in the EI owing to the implementation of multilevel treatment is demonstrated.