An Optimal Water-Waste Nexus for an Eco-Industrial Park

Resource sustainability is a top priority agenda nowadays which is extensively discussed in the circular economy concept. Reduction of water consumption, as well as final waste generation can be achieved by implementation of process integration and optimisation techniques. Promotion of eco-industrial park (EIP) as an option to improve conventional industrial park will enable the symbiotic participation of all parties, including the nearby domestic community. In this paper, a mathematical model is developed to maximise profit generation from simultaneous resource recovery and water integration from the wastewater. The novelty lies on consideration of multiples sources from industrial and domestic streams, while performing simultaneous regeneration, recycle, and reuse of water and resource recovery works. A superstructure and the associated mathematical equations are developed. Five types of contaminants i.e Chemical Oxygen Demand (COD), Total Dissolved Solid (TDS), Total Suspended Solid (TSS), Chromium (Cr), and Zinc (Zn) will be considered in the model. Generic Algorithm Modelling System (GAMS) is used as the optimisation tool. The case study result shows that a total annual profit of 200,788 USD/y could be generated by the centralized wastewater utility service provider and the payback period is less than 3 y. As a result, 37 % of freshwater could be minimized and 0.02 dry t/h of waste metal precipitate can be recovered from the wastewater. The demand side is also economically benefitted as the cost of supplied water is 10 % lower than the typical cost. The model provides insight on how the domestic and industrial sources can be symbiotically integrated, while retaining economic benefits to the centralized wastewater utility service provider and the demands.