Dewatering of High Salinity Brines by Osmotically Assisted Reverse Osmosis

In reverse osmosis (RO), the upper concentration limit to which a brine can be dewatered is about 90 g/L total dissolved solids (TDS). This limitation contravenes the use of RO for the management of brines extracted for subsurface pressure management inthe geologic carbon dioxide storage (GCS). Some extracted GCS brines have a total dissolved solids (TDS) of 100 225 g/L making them too saline to be dewatered by reverse osmosis. A proposed approach to dewater high salinity brines by reverse osmosis, called osmotically assisted reverse osmosis (OARO), uses an engineered osmotic pressure difference to lower the feed pressures needed for reverse osmosis to occur. This study will experimentally show positive water flux for a bench scale evaluation of OARO for feed solutions having a salinity up to approximately 3.5 times greater than seawater using a driving pressure of only 27.6 bar.