What is water softening?
When water contains a significant amount of calcium and magnesium, it is called hard water. Hard water is known to clog pipes and to complicate soap and detergent dissolving in water. Water softening is a technique that serves the removal of the ions that cause the water to be hard, in most cases calcium and magnesium ions. Iron ions may also be removed during softening.
A water softener reduces the calcium, magnesium, and to some degree manganese and ferrous iron ion concentration in hard water. These “hardness ions” cause three major kinds of problems. The metal ions react with soaps and calcium sensitive detergents, hindering their ability to lather properly and forming an unsightly
precipitate— the familiar scum or “bathtub ring”.
Presence of “hardness ions” also inhibits the cleaning effect of detergent formulations. More seriously, calcium and magnesium carbonates tend to adhere to the surfaces of pipe sand heat exchanger surfaces. The resulting scale build-up can restrict water flow in pipes. In boilers, the deposits act as thermal insulation that impedes the
flow of heat into the water; this not only reduces heating efficiency, but allows the metal to overheat which, in a pressurized system, can lead to failure.
The presence of ions in an electrolyte can also lead to galvanic corrosion, in which one metal will preferentially corrode when in contact with another type of metal. The use of water softeners can aggravate this and cause sacrificial anodes in hot water heaters to corrode more quickly. Conventional water-softening devices intended
for household use depend on an ion-exchange resin in which “hardness” ions trade places with sodium ions that are electrostatically bound to the anionic functional groups of the polymeric resin.
Why is water softening applied?
Water softening is an important process, because the hardness of water in households and companies is reduced during this process. When water is hard, it can clog pipes and soap will dissolve in it less easily. Water softening can prevent these negative effects. Hard water causes a higher risk of lime scale deposits in household water
systems. Due to this lime scale build-up, pipes are blocked and the efficiency of hot boilers and tanks is reduced. This increases the cost of domestic water heating by about fifteen to twenty percent.
Another negative effect of lime scale is that it has damaging effects on household machinery, such as laundry machines. Water softening means expanding the life span of household machine, such as laundry machines, and the life span of pipelines. It also contributes to the improved working, and longer lifespan of solar heating
systems, air conditioning units and many other water-based applications.
What does a water softener do?
Water softeners are specific ion exchangers that are designed to remove ions, which are positively charged. Softeners mainly remove calcium (Ca2+) and magnesium (Mg2+) ions. Calcium and magnesium are often referred to as ‘hardness minerals’. Softeners are sometimes even applied to remove iron. The softening devices are able to remove up to five milligrams per litre (5 mg/L) of dissolved iron. Softeners can operate automatic, semi-automatic, or manual. Each type is rated on the amount of hardness it can remove before regeneration is necessary.
A water softener collects hardness minerals within its conditioning tank and from time to time flushes them away to drain.
Ion exchange are often used for water softening. When an ion exchanger is applied for water softening, it will replace the calcium and magnesium ions in the water with other ions, for instance sodium or potassium. The exchanged ions are added to the ion exchange reservoir as sodium and potassium salts (NaCl and KCl).