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Electrodialysis – ED, EDR, EDM

Electrodialysis (ED) & Electrodialysis Reversal (EDR) are used around the globe in many industrial, laboratory and recycling environments. ED is an industrial membrane separation process in which ions are transported through ion-permeable membranes, from one stream to another, under the influence of a voltage potential gradient.  The electrical charges on the ions allow them to be driven through the anion- and cation-exchange membranes (e.g., Excellion). Applying a voltage between electrodes generates the DC voltage potential required for this. Since membranes used in electrodialysis have the ability to selectively transport anions and cations, and reject ions of the opposite charge, concentration, removal, and separation of salts can be achieved.

EDR (ED Reversal) is a technique developed by Ionics for streams which foul the ED. The periodic reversal allows the foulants to be driven off the membrane surfaces into the concentrate stream.

EDM (ED Metathesis) is an ED developed and patented by DuPont years ago, which separates salt mixtures that would precipitate if concentrated, into 2 separate streams that do not precipitate. For example, separating and concentrating CaSO4 into 2 streams of Na2SO4 and CaCl2. Contact us at SnowPure to find out how EDM can be used for ZLD, Zero Liquid Discharge.



ED has a wide range of applications in many fields:

Standard ED applications include concentrating salts (brine), reducing electrolyte content, and recovering electrolytes. For example,

  • Seawater desalination
  • Concentration of RO brine and other wastes
  • Salt removal from foods and beverages
  • Impurity (chloride) removal from antifreeze (for recycle/reuse)
  • Electroless plating baths
  • Laboratory separations

Specialty ED can do some amazing things,

  • Bipolar ED: used for conversion of salts into the acid- and base-forms
  • Metathesis ED: used to concentrate ion mixtures that would otherwise precipitate.

SnowPure has extensive experience in water purification technologies. This gives us the ability to work with our customers to ensure the best solutions are being used to meet their needs.

Please contact SnowPure to discuss your ED requirements.

Request an ED Quotation