ABSTRACT
Pressure-retarded osmosis (PRO) is a promising technology to reduce the specific energy consumption of a seawater reverse osmosis (SWRO) plant. More energy can be generated if the brines from SWRO are used as the draw solution and diluted to the seawater level in a PRO system. Detailed integrated SWRO–PRO processes are developed in this study with the option to form a closed-loop SWRO–PRO process that can substantially reduce the pretreatment cost of desalination. The governing mathematical models that describe both the transport phenomena on a module level and the energy flow on a system level are developed to evaluate the performances of the SWRO–PRO processes. The model aims to investigate the performance of the hollow fibers as dilution occurs and provides guidelines on hollow fiber module design and process operation. Furthermore, a strategy has been proposed to maximize the operating profit of the SWRO–PRO process while maintaining the highest power density of the PRO membranes.
