Perspective in resource recovery from reverse osmosis brines: the case for sustainable seawater refineries for small islands
Abstract
Reverse osmosis has become the dominant technique for desalination while at the same time there is a steady increase in reliance on desalination systems for water production globally. Resource recovery and mitigation of adverse effects from brine discharge are important factors and are increasingly being considered by researchers and industrial actors. The island nation of Aruba, with over 100 years of commercial desalination history, is used as a case study to illustrate the possibilities of shifting from centralized seawater desalination plants to seawater refineries in which freshwater is considered only one of the possible products. We identify possible economic value from desalination plants of medium scale (as is the case in Aruba) from the production of magnesium, caustic soda, chlorine-based products and rubidium and possible energy recovery possibilities through osmotic gradients and/or hydrogen storage while at the same time highlighting the insufficient potential for lithium harvesting from seawater desalination brines. We have found that the economic value from resources recovered from brine may be even larger than the value of the freshwater produced by these plants. Furthermore, reduction of salinity and quantity of brine can reduce the overall ecological impact from current brine effluents. © 2023 Society of Chemical Industry (SCI).