Q. A sample of water analysis was found to contain temporary magnesium hardness 25 mg/L. Permanent magnesium chloride hardness 15 mg/L and permanent calcium sulphate hardness 20 mg/L, SiO₂  = 30kg/L. Calculate the lime and soda required for softening 30,000 litters hard water.

Ans.

Conversion of CaCO₃ equivalent

SiO₂ do not required Lime soda.

Lime required = 74/100(Temp. hardness + Perm. Hardness) = 74/100(17.12 + 15.12) = 24.30 mg/L

Lime required for 30000 Litre hard water = 24.30*30000 = 729 mg

Soda required = 106/100(perm. Ca hardness + perm. Mg hardness) = 106/100(15.72 + 14.70) = 32.24 mg/l

Soda required for 30000 litre hard water = 32.24 mg/λ*30000λ = 967.2 mg