Ion Exchange Systems
An ion exchange water treatment system is a specialized technology used in water and wastewater treatment to remove dissolved ions and contaminants from water. All natural waters contain, in various concentrations, dissolved salts which dissociate in water to form charged ions – positively charged ions are called cations and negatively charged ions are called anions.
Ion exchange resins can be thought of as powerful magnets that attract and hold the ions of contaminating minerals from the passing source water, by an electromagnetic attraction. The two main types of ion exchange resins are cation resins, which are negatively charged and attract positively charged ions, and anion resins, which are positively charged and attract negatively charged ions. Cation exchange resins naturally attract a certain set of minerals, while anion exchange resins attract another set of minerals.
The polymeric resin beads are treated such that they contain thousands of tiny cracks, thus increasing their surface area. As source water passes through the cation and anion resin beads, molecules with minerals are left “clinging” to the many surfaces of the beads. This anion and cation exchange process is reversible, so when the beads are fully loaded with minerals, the resin can be regenerated, which will flush the minerals out, and return the resin to like-new condition. The regenerant solution is typically a concentrated salt, acid or caustic solution that replaces the contaminants that have been absorbed onto the resin surface with the cations or anions.
The ion exchange resin regeneration operations for IX systems are more complicated than for typical water filtration operations, and are normally fully automated.
The geometric shape, size, and structure of IX resins can vary from one type to the next. Most IX exchange systems employ a resin bed consisting of tiny, porous microbeads, though some systems, such as those used for electrodialysis, use a sheet-like mesh resin. IX resin beads are usually small and spherical, with a radius measuring just 0.25 to 1.25 millimeters in size.
WETS has designed and installed ion exchange treatment systems for water hardness removal and for radionuclides, including radium water treatment.
For water hardness removal systems, the ion exchange technology works by replacing calcium and magnesium ions in water with sodium ions on a strong acid cation resin. For regeneration, a concentrated solution of sodium chloride brine (typically 8 to 12 percent) is used to force accumulated hardness and other ions off the resin beads.
Radionuclides are large ions relative to other ion exchange applications, and special resins have been developed that provide better performance in these applications. The reason is these large ions tend to foul standard resin more easily, which, for the standard resins, raises issues with performance over time and suitability of landfill disposal for the resin at the end if its life. The specialty resins have an activated outer shell and inert core, which improves the ion exchange resin regeneration capability and overall performance of the resin. The reduced resin fouling increases likelihood the resin at the end of life will be suitable for landfill disposal.
While widely used for water softening, ion exchange systems have numerous other applications in metals removal, dealkylation and other specialized services. A well-designed anion and cation exchange column system must conform to the specific conditions of each application. These conditions include treatment stream composition and properties, targeted contaminants and desired level of removal, and minimization of operating and maintenance costs. WETS team of professional engineers has many years of experience as a water treatment supplier and ion exchange company developing customized designs for our clients. From customization of your pilot plant study, through conceptual and detailed design, and equipment manufacture and installation, the WETS team of professionals stand ready to develop the optimal solution to your water treatment problem.
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Whether you want a new water treatment system installed, need your current one inspected and repaired, or just want a free quote, contact the WETS LLC. With years of experience in the industry, our skilled team members are trained and knowledgeable with a variety of leading water equipment and products. Our certified water purification experts are here to help.