20190114_Energy recovery by pressure retarded osmosis (PRO) in SWRO-PRO integrated processes


1. Title, Journal and Authors

Title: Energy recovery by pressure retarded osmosis (PRO) in SWRO-PRO integrated processes

Journal: Applied Energy

Authors: Chun Feng Wana, Tai-Shung Chunga,b*

a. Department of Chemical and Biomolecular Engineering, National University of Singapore, 4 Engineering Drive 4, Singapore 117585, Singapore

b. Water Desalination & Reuse (WDR) Center, King Abdullah University of Science and Technology, Thuwal 23955-6900, Saudi Arabia


2. Summary

Pressure retarded osmosis (PRO) is a promising technology to reduce the specific energy consumption of a seawater reverse osmosis (SWRO) plant. In this study, it is projected that 25.6–40.7 million kWh/day of energy can be recovered globally, 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. Determining the
dilution factor and the corresponding operating pressure of PRO is the key to optimize the integrated process.The specific energy consumptions of three SWRO-involved processes; namely, (1) SWRO without a pressure exchanger, (2) SWRO with a pressure exchanger, and (3) SWRO with pressure exchangers and
PRO are compared. The results show that the specific energy consumptions for the above three processes are 5.51, 1.79 and 1.08 kWh/(m3 of desalinated water) for a 25% recovery SWRO plant; and 4.13, 2.27 and 1.14 kWh/(m3 of desalinated water) for a 50% recovery SWRO plant, using either freshwater or wastewater as the feed solution in PRO.


3. Contact

 Sung Ho Chae (Ph.D. program)
Environmental Systems Engineering Lab.
School of Environmental Science & Engineering
Gwangju Institute of Science and Technology
1 Oryong-dong Buk-gu Gwangju, 500-712, Korea
Phone : +82-10-8734-8657
E-mail : kha5s@gist.ac.kr
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