Removal Hardness of Water:
It is classified into two main categories:
Removal of Temporary Hardness:
i. By Boiling: Temporary hardness in water can be removed by boiling when bicarbonates of Ca, Fe, and Mg in water are precipitated as their insoluble carbonates.
ii. Clark’s Process: Temporary hard water is treated with a calculated amount of time.
Removal of Permanent Hardness:
i. Soda Process: Permanent hardness in water can be removed by adding Na2CO3 to it so as to precipitate insoluble CaCO3 and MgCO3.
ii. Lime-Soda Process: Both temporary and permanent hardness in water can be removed by adding calculated amount of Na2CO3 and Ca(OH)2.
iii. Permutit Process: Permutit Process is the best and most widely used method of removing both temporary and permanent hardness in water. Permutit is the trade name for artificially prepared sodium alumino silicate allied to the natural mineral Zeolite.