Water Softening

The ion exchange water softener is one of the most common tools of water treatment. Its function is to remove scaleforming calcium and magnesium ions from hard water. In many cases soluble iron (ferrous) can also be removed with softeners. A standard water softener has four major components: a resin tank, resin, a brine tank to hold sodium chloride, and a valve or controller.

The softener resin tank contains the treated ion exchange resin – small beads of polystyrene. The resin bead exchange sites adsorb sodium ions and displace multivalent cations during regeneration with 6-10% solution of NaCl. The resin has a greater affinity for multivalent ions such as calcium and magnesium than it does for sodium. Thus, when hard water is passed through the resin tank in service, calcium and magnesium ions adhere to the resin, releasing the sodium ions until equilibrium is reached.