Electrodialysis uses ion-exchange membranes (IEMs) to separate salt ions in water under an electrical field. Electrodialysis has a high tolerance of silica, hardness, chlorine residual, and organic matter; therefore, it could achieve higher water recovery and lower costs than reverse osmosis (RO) during the treatment of impaired waters. Another unique advantage of electrodialysis is the selective separation of monovalent ions (such as Na+, K+, NH4+, Cl-, and NO3-) versus multivalent ions (e.g., Ca2+, Mg2+, SO42-, PO43-). Selective removal of Na+ over Ca2+ and Mg2+ is especially important if the treated water is used for irrigation. This study presented the advances in developing innovative, nanocomposite IEMs to enhance monovalent permselectivity, reduce membrane organic fouling and biofouling, and improve energy efficiency. Bench and pilot-scale experiments were conducted to evaluate the desalination performance during the treatment of wastewater, brackish water, and RO concentrate. Polymer-modified membranes demonstrated the Na-selectivity up to 9 times better than the unmodified membranes. Membrane fouling, in particular biofouling, was significantly reduced by membrane coating with hybrid conductive polymers and nanomaterials such as titanium dioxide (TiO2) and graphene oxide (GO). GO coating significantly improved the desalination efficiency of both cation and anion exchange membranes during wastewater treatment. The study demonstrated the bench-scale testing results could be used to simulate and project desalination performance and ion selectivity of the pilot- and full-scale electrodialysis applications.

Recent advances in electrodialysis for water reuse, desalination, and concentrate treatment

ACS Fall 2021

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.