The reclamation of brine generated from desalination process by bipolar membrane electrodialysis

• A hybrid process that coupled ED with BMED was designed for brine reclamation.
• Some application-oriented issues of the reclamation scheme were explored.
• The RSM was employed to understand and optimize the hybrid process.

Some techno-economical analyses and environmental impact evaluation have proved that bipolar membrane electrodialysis (BMED) is feasible for the reclamation of industrial saline water. However, to date, the technology cannot be put into practice due to some unsolved application-oriented problems, such as the requirements of BMED for feed solution, the availability of the produced acid and base, relatively high salt concentration of the effluent, and relatively low desalinating efficiency and capacity. In this work, a novel hybrid process, which coupled conventional electrodialysis installed with monovalent selective cation-exchange membranes with BMED running in a constant-voltage mode, was designed to reclaim brine generated from surface water desalination by the ion-exchange process. Subsequently, the response surface methodology was employed to establish the empirical models for understanding the influences of some initial operating conditions on BMED performance. Finally, the BMED-based reclamation scheme was confirmed again by a continuous BMED experiment on real solution. Specially, the effects of product concentration on current efficiency and energy consumption were investigated. In this case, an acceptable current efficiency and energy consumption were obtained on the basis of the conventional membranes and spacers when the product concentration was set as 0.9 M, which is adequate for the regeneration of ion-exchange resins.