Optimal design and techno-economic evaluation of renewable energy powered combined reverse osmosis desalination and brine treatment unit

The reverse osmosis (RO) desalination technique has been identified as a viable means of freshwater production, but its high energy requirement, high cost, and waste (brine) remain serious challenges. This study, therefore, explores efficient energy from renewable energy sources (RES) and brine management in the production of freshwater using the integration of RO, electro-dialysis (ED) and crystallization methods. The objective of this study is to minimize the levelized cost of energy and brine production whilst maximizing freshwater and salt production. The proposed design is such that the feed water (saline water) is passed through the RO unit for desalination; the brine produced from the RO unit is further desalinated by the ED method, leaving a very high concentration to be crystallized into soluble salts thereby achieving a zero brine production. Furthermore, for energy-efficient management, an optimal sizing of energy sources which includes grid power, wind power and solar power, was carried out considering mitigation of carbon emission and its cost and the intermittent limitation of the RES. This integrated design ensures that the internal and external costs of desalination are evaluated and minimized.