Electrodialysis for sustainable management of seawater-brine: Increasing water recovery via production of hypersaline solution for brine-mining processes

Abstract

The adoption of desalination processes for the production of fresh water is one of the main solutions to water scarcity. Desalination recovers fresh water from saline solutions, yet increasing their concentration during the process and producing a brine. The latter can have an environmental impact when discharged, thus requiring suitable disposal strategies or post-treatments.Among the processes reported in the literature, in this study, electrodialysis (ED) is studied as possible technology to be coupled to a standard desalination process in order to increase the global water recovery and produce hypersaline solution for subsequent brine-mining processes for the recovery of useful minerals. The performance in terms of Specific Energy Consumption (SEC), Total Recovery Ratio (RRTOT) and Additional Levelized Cost Of Treatment (ALCOT) are assessed by considering industrial ED unit equipped with standard membranes and high-performing membranes. The influence of operating conditions such as electric voltage, electric current and solutions residence time on the performance of the system is investigated. Results reveal that, in the best conditions, a RRTOT between 55 % and 78 % is achieved with SEC in the range of 0.5–1.9 kWh·m−3P and with ALCOT in between 0.10 €·m−3P and 0.21 €·m−3P. The integration of electrodialysis into standard desalination processes improves the efficiency and the sustainability of desalination, minimizing waste (zero-liquid discharge) and increasing productivity.