Valorization of seawater desalination brines through the integration of Eutectic Freeze Crystallization and Electrodialysis with Bipolar Membranes innovative technologies

Abstract

European policy encourages the adoption of sustainable systems that promote the efficient use and recovery of resources. Accordingly, this study proposes integrating two innovative technologies, including Eutectic Freeze Crystallization (EFC) and Electrodialysis with Bipolar Membranes (EDBM), for treating seawater desalination brines. Two experimental campaigns were conducted to assess the viability of this novel treatment chain. Using two lab-test rig units, the effect of various operating conditions on the outputs and general performance of both EFC and EDBM was evaluated. Firstly, results showed that EFC could manage seawater brines to (i) obtain pure sodium sulphate, and fresh water in the form of ice and (ii) provide a NaCl concentrate stream to EDBM. Secondly, regardless of the feed salt concentration, EDBM can operate with high current densities without significantly affecting the current efficiency, thus resulting in high conversion rates. Within the circular economy concept, the present study demonstrates that this integrated system is effective for minimizing seawater desalination waste streams.