Cost-based optimization, feasibility study, and sensitivity analysis of forward osmosis/crystallization/reverse osmosis with high-temperature operation for high-salinity seawater desalination

Abstract

Seawater desalination plants using reverse osmosis (RO) in high temperature and high-salinity conditions, such as in the Middle East, face challenges such as limited achievable recoveries and high energy costs. This study evaluated the economic feasibility under seawater and high-salinity conditions by introducing a forward osmosis/crystallization/reverse osmosis (FO/Cry/RO) hybrid process. The optimization results were then used to compare the specific water cost (SWC), specific energy consumption (SEC), recovery, and permeate quality of the hybrid process with two different draw solutes and a conventional seawater RO process. In addition, a sensitivity analysis was conducted to determine how individual process parameters and operating conditions affect the economic feasibility of the proposed process under seawater and high-salinity conditions. The FO/Cry/RO hybrid process achieved a higher recovery with a lower SWC and SEC as the feed concentration increased compared to the conventional RO process. Utilizing waste heat further increased the economic advantages of the proposed process. In addition, much higher permeate quality can be obtained depending on the type of draw solute. The results of this study revealed that the proposed hybrid system outperformed the conventional RO process in terms of both energy efficiency and cost-effectiveness for seawater desalination under high-temperature and high-salinity conditions.