(565c) Hybrid Water Treatment Processes Utilizing Forward/Reverse Pressure Driven Processes and Reverse Electro-Dialysis

Reverse osmosis (RO) has become the preferred process for seawater desalination. The preference for reverse osmosis is due to the substantial energy savings that can be realized.

Forward osmosis (FO) recently has generated substantial interest as a lower cost alternative to reverse osmosis. In forward osmosis water is pulled across the membrane into a solution of higher osmotic pressure in contrast to reverse osmosis where water is forced across the membrane by pressurizing the higher osmotic pressure stream.

We examine the potential use of hybrid RO/FO for desalination. RO and FO can be used synergistically for desalination. However, FO also can be used to generate power by mixing the concentrated brine with seawater. The potential for integration of FO’s separation and power generation into a desalination plant will be discussed. Process optimization relies on tracking osmotic pressure differences through the process and evaluating the effectiveness of the separation and power generation capabilities of the two unit operations. The trade-offs between use of FO and reverse electro-dialysis (RED) for power generation are discussed.