Water softeners are primarily used to remove calcium and magnesium ions from boiler makeup water. If not removed, these ions can be the basis for forming insoluble compounds that will precipitate in boiler systems. A water softener eliminates this problem by replacing precipitate-forming ions with sodium ions.

Since sodium based compounds are very soluble, precipitates formed by hard water can be eliminated. In a water softener, ion exchange occurs as the water runs through a bed of small plastic resin beads which are saturated with sodium ions. As the water, containing calcium and magnesium ions, flows past the resin beads, calcium and magnesium ions “stick” to the ion exchange resin, liberating the sodium ions, which then go into solution. Eventually, the resin beads contain nothing but calcium and magnesium ions and no sodium. At this point, softening no longer occurs and hardness ions (Ca and Mg) begin to leak through the bed. When leakage occurs, or prior to the resin being exhausted, it is time to regenerate the media.

WATER SOFTENING METHODS

The most common means for removing water hardness rely on ion-exchange polymers or reverse osmosis. Other approaches include precipitation methods and sequestration by the addition of chelating agents.