Advantages and disadvantages of cold lime soda process

Cold lime soda process, when hard water is treated with calculated amount of lime [Ca(OH)₂] and soda ash (Na₂CO₃) at room temperature 25ºC, the soluble Ca and Mg salt present in hard water are chemically converted into ppt. of calcium carbonate (CaCO₃) and magnesium hydroxide [Mg(OH)₂]. These ppts are removed by filtration. Thus soft water is obtained.

Advantages of cold lime soda process

1. It can be carried out by four ways. So as per necessary, its required type can be used.
2. Soft water obtained by this process has residual hardness about 50-60 ppm.

Disadvantages of cold lime soda process

1. It is slow process because reactions during water softening takes place in very dilute solutions and room temp.
2. It does not give soft water having residual hardness less than 50-60 ppm.
3. It requires coagulant for setting particles of ppt. formed during reaction of water softening.
4. Softening capacity of this process is less.
5. Soft water obtained by this process consists of dissolved gases.

Cold lime soda process