Ion Exchange Technology

Ion exchange systems provide a highly effective way of removing dissolved and ionised impurities in water. Our ion exchange technologies are highly adaptable systems, available in a range of configurations to meet specific industry challenges and outlet water requirements. We provide cost-effective packed-bed, counter-current systems and conventional downflow skids for a wide range of applications, delivered through three core, ion exchange technologies:

What is ion exchange?

In its purest form, water is made from simple molecules consisting of one oxygen and two hydrogen atoms. However, all sources of water contain impurities, some are suspended matter and others are dissolved. While Envirogen’s filtration technologies target and remove insoluble, suspended elements, our ion exchange technologies target and replace charged, ionised, dissolved salts.

Ion exchange is the process by which problematic dissolved ions in water, such as calcium (Ca++), magnesium (Mg++), chloride (Cl-) and nitrate (NO3-), are exchanged for less problematic ions, such as sodium (Na+), hydrogen (H+) and hydroxide (OH-).

This process can strip out scale-forming ions and those that might cause issues with industrial processes. Due to the charge carried by dissolved ions, conductivity is a useful measure of the level of ions in water.

How does ion exchange in water treatment work?

At the centre of all ion exchange technologies are polymer beads arranged in a resin bed. Each porous bead measures around 0.6mm in diameter and contains permanently fixed ions of a particular type with a particular charge. Each permanent ion has a mobile counterion of the opposite charge that maintains neutrality within the resin bed. This counterion can exit the bead structure and be interchanged with other ions, thereby driving the ion exchange process.

As water passes through the resin beds at pressure, the dissolved ions can penetrate the porous bead structure. The heavier, more challenging ions are swapped for the lighter mobile ions and are maintained within the structure of the bead. The lighter ions then exit the resin bed in the water stream. This process can be referred to as water softening or demineralisation/deionisation, depending on the ions exchanged and the mobile counterions used in the resin bed.

The capacity of an ion exchange system is limited by its design and the number of exchange sites available on each bead. Resins aren’t single-use media so periodic regeneration happens once the beds are exhausted.

We offer a range of modular and bespoke ion exchange solutions to meet your exact water treatment needs.

Industrial water softening technology

Industrial water softening technology deals with scale-forming ions that are positively charged. For this reason, a single-stage cation resin is used to capture and exchange sparingly soluble, scale-forming ions, such as Ca++ and Mg++, for less problematic Na+ ions. Calcium ions (Ca++) being exchanged for sodium (Na+) ions:

Regeneration stores Na+ ions in water softening resins.

Resin beds have a limited capacity and once the ion exchange sites are saturated, regeneration needs to take place. This regeneration process enables repeated use of the same resin beds, delivering a low total cost of ownership.

To regenerate an ion exchange water softener, a brine solution, rich in Na+ ions, is introduced to reverse the process and drive the scale-forming Ca++ and Mg++ ions into a waste stream.

Resin beads undergoing regeneration:

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North America Head Office

Envirogen Technologies
700 Rockmead Drive, Suite 100
Kingwood, TX
77339

T: 877 312 8950

United Kingdom Head Office

Envirogen Group
Unit 9, Wimsey Way
Alfreton Trading Estate
Alfreton, DE55 4LS

T: +44 (0) 1773 441029

Europe Head Office

Envirogen Technologies bv
Penningweg 71
1507 DG Zaandam
The Netherlands

T: +31 75 204 7200