Recovering Osmotic Power in SWRO Plants

Abstract

For the last two decades, leading desalination companies have focused on energy savings. Nearly half of the energy invested in seawater desalination processes can now be recovered. The process of recovering gauge pressure from seawater reverse osmosis (SWRO) desalination plants, which began 20 years ago, has now reached 95–96 percent efficiency. To date, the industry has not found a practical way to recover osmotic pressure present in SWRO brine, the main obstacle being several types of concentration polarization (CP). This article analyzes how researchers have overcome the CP phenomenon, presents an overview of RO membranes suitable for forward osmosis power generation, makes recommendations to membrane manufacturers, and introduces a method that allows simultaneous power recovery of gauge and osmotic pressure.