Desalination of high salinity produced water using natural gas hydrate

Hydrate-based desalination was suggested as a new method in recent years. In this study, compressed natural gas (CNG), mixed with various produced water samples and the hydrate formation reactions were performed at the pressure of about 95 bar and temperature of 274.2 K. After hydrate formation, the concentrated salty water was extracted from the reactor and the formed hydrate was washed with a suitable amount of fresh water to successfully improve desalination efficiency. Then, the hydrate was dissociated to produce fresh water. Desalination efficiencies for dissolved mineral extraction from produced water samples were measured and it has been found that with 3-stages hydrate process, 79.5%-84.3% of dissolved mineral components will be removed using gas hydrate formation. This study indicated that the CNG hydrate formation for desalination can be applied for produced waters with initial total dissolved solids (TDS) less than 160,000 mg/L. (C) 2017 Taiwan Institute of Chemical Engineers. Published by Elsevier B.V. All rights reserved.