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Ion Systems

Waterex offers two ion exchange technologies each for different purposes.  Typically electro deionisation is used to produce high quality water whilst more traditional ion exchange is used for processing minerals such as Uranium.

Electro Deionisation

The EDI design combines two well established water purification technologies, electrodialysis and ion exchange deionisation. Through this revolutionary technique, dissolved salts can be removed with low energy cost and without the need for regeneration: the result is high quality water which can be produced continuously at substantial flow rates.

EDI removes ions from water by forcing them out of the feed stream into adjacent streams via electric potential. Resins allow for more efficient migration of ions in very low conductivity water and behave as an ion conduit, not an ion reservoir.

The electro deionisation process utilises a combination of ion selective membranes and ion exchange resins sandwiched between two electrodes (anode and cathode) under a DC voltage to remove ions from pretreated RO water.

Ion selective membranes operate using the same principles and materials as ion exchange resins and they are used to transport specific ions away from their counter ions. Anion selective membranes are permeable to anions but not cations and the reverse is true of cation selective membranes.

The RO feed to the EDI module is split into three separate streams;

  • Product stream (90+% water recovery)
  • Concentrate stream (typically 10%, may be recycled to RO feed)
  • Electrolyte stream (1%, anolyte and catholyte to drain)

The Waterex Electropure EDI units produce high quality demineralised water as a final polisher from an RO quality feed. This technology is an alternative to the application of mixed bed resins and has the following advantages;

  • No chemicals required for regeneration
  • Continuous operation (No regeneration cycle required)
  • No hazardous wastes generated
  • Simple system (No concentrate recirculation or brine injection)
  • No resin change out necessary
  • Consistent and predictable results
  • Improved reliability (less system components)
  • Lower operating costs
  • Expandable modular system
  • Smaller installed footprint

High temperature stable EDI for pharmaceutical, medical or sterile water applications include:

  • Sanitation without chemicals
  • High temperature design and materials
  • High temperature resins
  • Proven up to 104 cycles at 80°C
  • Stainless steel covers

Applications include:

  • Boiler feed water
  • Semiconductors
  • Pharmaceutical
  • Laboratories
  • Food and Beverage
  • Biomedical
  • Any DI water application
  • Units for larger flows incorporate multiple standard modules.

The photograph below show a containerised demineralised water plant, comprising filtration and RO unit to produce suitable feed for electro deionisation via the EDI units. This plant is situated in an oil and gas processing plant.

Ion Exchange

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