Ion Selectivity of Electrodialysis for Desalination and Reuse Enhancement

Selective separation of mono- and multi-valent ions has important applications in water reuse, desalination, and salt production, by adjusting ion composition to meet product water quality requirements. In this study, we developed an innovative monovalent permselective cation-exchange membrane (CEM) CR671 by modifying normal grade membrane CR67 with polyethylenimine coating. Bench- and pilot-scale electrodialysis experiments were conducted at the Kay Bailey Hutchinson Desalination Plant to treat brackish groundwater and RO concentrate and to reduce sodium adsorption ratio and salt concentration of the product water for irrigation. The desalination performance and selective transport of mono- and di-valent ions were investigated under different operating conditions.