There are different water softener are used depends on the application and condition of water hardness. Following water softeners are used for water softening.
- Ion exchange water softener
- Cold and hot lime-soda process
- Zeolite or permutit water softener
- Reverse osmosis water softener
- Electric or Magnetic water softener (electrodialysis process)
Ion Exchange Water Softener
This type of Water softener works on the ion exchange principle. In ion exchange process, water passes through a bed, generally made by sulfonated polystyrene divynalbenzene spherical resin. This resin beads is supersaturated with sodium. During the water softening this sodium ions are exchange by the hardness ions. Again these sodium ions are regenerated by passing a brine solution through the ion exchange column.
Lime-soda softening process
In the lime-soda water softener process soluble magnesium and calcium salts are made insoluble salts like calcium carbonate and magnesium hydroxide by the treatment with calcium hydroxide and soda ash. After removal of this precipitated, we obtain soft water. Before water treatment calculate the amount of temporary and permanent hardness, and then estimate the amount of lime and soda ash and added control with careful. By this lime-soda water softener process both temporary and permanent hardness are removed. There are two type lime-soda process; cold lime-soda process and hot lime-soda process.
Zeolite or permutit water softener
Zeolite is a porous natural mineral and its general chemical formulae AlxSiyO2(x+y) (without water molecules). The natural zeolite that is used as water softener is gluconites or greensand. But permutit is the artificial zeolite that is most used in water softening. The general chemical formula of permutit is Na2O, Al2O3, nSiO2, xH2O. They can exchange cation, hence can remove calcium and magnesium ions from water. As a result water becomes soften.
Reverse osmosis water softener system
In the Reverse osmosis water softener system a semi-permeable membrane is used as a filter. In this process water is allowing to pass through the membrane with the help of osmotic pressure. As a result pure water is passing the other side leaving the contaminant behind. When the concentrations of a particular species exceed the solubility product, then it is precipitate.
Electric or Magnetic water softener
In this water softener process create a magnetic field and hard water is passing through the magnetic field. Hard water contains cations and anions which are positively and negatively charged respectively. Hence they can be influence by the magnetic field and separate from the water. Therefore water becomes soften.