Question

A zeolite softener was 90% exhausted by removing hardness of 10,000 l of hard water sample. The exhausted zeolite bed required 200 l of 3% nacl solution for its complete regeneration. Calculate hardness.

Answer 1

Answer: 200 L of 3% NaCl solution is required for the formation of zeolite bed which is exhausted.

Explanation:

100g of NaCl→1 litre

1g=1000mg102×103mg of NaCl→1 litre    102g105mg of Nacl→1 litre

400 litres solution cxontains −>400×105mg of NaCl

Now,

CaCO3

equivalent =400×105×100/(2×58.5)=341.88×105mg of CaCO3

equivalent

1 litre =341.88×105ppm104 litre =xX=341.88×105×104

Hardness of water sample =341.88×109ppm