(613g) A Novel Variable Configuration Design for Ultra-High Recovery Reverse Osmosis Desalination of Brackish Water

A novel transient and cyclic design is proposed for ultra-high recovery reverse osmosis (RO) desalination of brackish water. The designed system consists of two subsystems -- a conventional multistage RO and a flow reversal and retentate recycle (FRRR) RO. The operation periodically switches between two different configurations -- a series connection of the two subsystems for full production, and a parallel connection for partial production and flushing of the most concentrated membranes using the under-saturated fresh feed. Such a transient and cyclic design concept incorporates beneficial features of ROTEC's flow reversal RO (FRRO) and DuPont/Desalitech's closed-circuit RO (CCRO) in a single system. It offers operational flexibility at ultra-high recoveries and requires a slight hardware modification to retrofit existing brackish water RO plants. Dynamic simulations show that concentration hotspots and overshoots are less severe than those in FRRO. It also avoids cycle-to-cycle salt buildups inevitable in CCRO given that it is an open-circuit design.

Reference:

[1] Li, M. An Improved Closed-Circuit RO (CCRO) System: Design and Cyclic Simulation, Desalination, 554, 116519, 2023.

[2] Li, M.; Waite, A.; Wang, S. Piloting Experience of ROTEC's Flow Reversal RO (FRRO) for 90% Recovery in Brackish Water Desalination, Desalination, 576, 117348, 2024.

[3] Li, M.; Li, J. Novel Variable Configuration Design for Ultrahigh Recovery RO Desalination of Brackish Water, Ind Eng Chem Res, 63, 5813-5822, 2024.