Water Softening Plants

Water Softening is the act of reducing the dissolved calcium, magnesium, and to some degree manganese and ferrous iron ion concentration in hard water. A common water softener is sodium carbonate (Na2CO3).

Conventional water-softening appliances intended for household use depend on an ion-exchange resin in which "hardness" ions trade places with sodium ions that are electro-statically bound to the anionic functional groups of the polymeric resin. A class of minerals called zeolites also exhibits ion-exchange properties; these minerals were widely used in earlier water softeners. Water softeners may be desirable when the source of water is a well, whether municipal or private.

In a water softener, the water to be treated passes through a bed of the resin. Negatively-charged resins absorb and bind metal ions, which are positively charged. The resins initially contain univalent hydrogen, sodium or potassium ions, which exchange with divalent calcium and magnesium ions in the water. As the water passes through the resin column, the hardness ions replace the hydrogen, sodium or potassium ions which are released into the water. The "harder" the water, the more hydrogen, sodium or potassium ions are released from the resin into the water.