Optimal Design and Operation of Hybrid Osmosis Processes for Simultaneous Production of Water and Power under Different Demand Conditions

This study investigates the optimal design of hybrid osmosis process systems for simultaneous seawater desalination and power production under different demand conditions. Optimization of four serial configurations that connect the RO, PRO, and FO processes with different order (i.e., RO-PRO, PRO-RO, FO-RO-PRO and PRO-FO-RO) are conducted by minimizing the total annual cost (TAC). The results show that the configurations with FO process are not cost-effective. The PRO-RO system is more favorable when the water demand is relatively large compared to the power demand and when higher water quality is demanded. Furthermore, a general RO/PRO structure that involves more flexible connection of streams is developed and optimized Compared with the serial configurations, the optimal general structures allow reductions of TAC up to 35%, depending on the demand scenarios. The results also reveal that there exists an optimal concentration of water permeate under a specific demand condition. The proposed model of process integration is effective for designing hybrid osmosis process systems to simultaneously produce water and power on demand.