An advantage for desalination of coastal saline groundwater over seawater in view of boron removal requirements

Abstract

Saline groundwater (SGW) from coastal aquifers is an alternative source for seawater in reverse osmosis (RO) desalination and holds several advantages over seawater. During seawater intrusion into the coastal aquifer, boron is adsorbed to the sediment, and its concentration is reduced with respect to seawater. This study aims to quantify the advantages of using SGW for RO desalination that result from lower boron concentration, stable temperature, and lower salinity as compared to seawater desalination. Firstly, SGW from the coastal aquifer in Israel was sampled and analyzed chemically, and desalination experiments were conducted to calibrate and validate an RO membrane transport simulation code. Secondly, simulations of a large-scale desalination plant (60 million m³ y⁻¹) that uses seawater and SGW as feed were performed. Results show that due to the lower boron concentration in SGW, lower capacity for the 2nd (boron removal) pass of desalination is needed, which saves 21% of the 2nd pass volume compared with seawater. An environmental techno-economic analysis shows that using SGW for desalination (compared with seawater) reduces the operational energy and costs by 17% (∼$4 million per year). Overall, SGW desalination is found to be energy and cost-efficient compared with seawater desalination, and thus, reduces the process environmental load.