(613d) Optimization of Hybrid RO-PRO Membrane Processes at the Water-Energy Nexus

Li, M., California State Polytechnic University
Water and energy are two of the most pressing problems faced by the world today. Membrane processes such as Reverse Osmosis (RO) and Pressure Retarded Osmosis (PRO) can help alleviate both challenges. This work focuses on systematic optimization of a two-stage hybrid RO-PRO process for energy-efficient seawater desalination which integrates RO for desalination and PRO for power generation into a single process. Such a process is of great significance at the water-energy nexus given that water production, pump energy consumption, and hydraulic/osmotic energy recovery are inherently intertwined. The optimization problem is formulated to minimize the Specific Energy Consumption (SEC) subject to specified total membrane area and total water recovery. By solving the optimization model the best design (e.g., allocation of membrane area among different units) and operating (e.g. applied pressure in each membrane unit) conditions are simultaneously determined. It is shown that the proposed two-stage RO-PRO is energy-efficient than other configurations currently available in literature for continuous membrane-based RO desalination. Challenges for commercial viability of RO-PRO are discussed.


M. Li. Optimization of Hybrid RO-PRO Membrane Processes at the Water-Energy Nexus, under review, 2018.