Highly saline brine is a rapidly growing environmental waste stream. Hypersaline streams are produced from critical economic activities, such as like inland desalination of groundwater and geological carbon sequestration. Reverse osmosis, the most energy-efficient desalination technology, cannot treat hypersaline brines. Evaporative technologies can, but only at tremendous energy cost. Desalinating these brines while using less energy will be an important environmental challenge.
We developed a new cascading osmotically-mediated reverse osmosis, COMRO, technology to extend membrane-based desalination into hypersalinity. The innovation uses novel countercurrent reverse osmosis stages, which have moderated osmotic pressure differences across the membrane, to achieve substantial energy savings and simultaneously depress the hydraulic pressure needed. Read our paper introducing COMRO and our follow-up studies on understanding the fundamental transport in COMRO and analysis of the energy requirement for various osmotically-enhance configurations.