Electrodialysis (ED)CharacteristicsSelective Ion Removal: Electrodialysis specifically removes dissolved ionic species (both cations and anions) from water.Ion Exchange Membranes: Utilizes cation and anion exchange membranes that allow selective passage of ions.Electric Field Driven: The process relies on an applied electric field to drive ion movement across membranes.Scalability: Suitable for a range of scales, from small laboratory setups to large industrial applications.Energy Efficiency: Generally more energy-efficient than thermal desalination processes, especially for brackish water desalination.Minimal Chemical Use: Requires minimal use of chemicals compared to traditional ion exchange processes.ProcessSetup:Stack Configuration: ED systems consist of multiple cell pairs, each containing a cation exchange membrane (CEM), an anion exchange membrane (AEM), and a spacer for the flow of dilute and concentrate solutions.Electrodes: An anode (positive electrode) and a cathode (negative electrode) are placed at either end of the stack.Ion Migration:Electric Field Application: When a direct current (DC) electric field is applied, cations migrate towards the cathode, passing through the CEM, while anions migrate towards the anode, passing through the AEM.Ion Separation: As ions move through their respective membranes, they are removed from the dilute compartments and collected in the concentrate compartments.Water Flow:Dilute Stream: Water flows through the dilute compartments, losing ions and becoming purified.Concentrate Stream: Water flows through the concentrate compartments, gaining ions and becoming a concentrated brine solution.Collection:Deionized Water: The purified (deionized) water from the dilute compartments is collected for use.Concentrated Brine: The concentrated brine from the concentrate compartments is collected for disposal or further treatment.FunctionIon Removal: The primary function of ED is to remove dissolved ionic contaminants (e.g., salts) from water to produce high-purity water.Desalination: Commonly used for desalination of brackish water and seawater.Water Purification: Applied in producing high-purity water for industrial, laboratory, and municipal applications.Waste Minimization: Reduces the volume of waste streams by concentrating dissolved ions into a smaller volume.Regeneration: Unlike conventional ion exchange, ED does not require frequent chemical regeneration, as the process is driven by electricity.