Q. How is true exhausted Zeolite bed regenerated? Give the merits and demerits of Zeolite process.

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State the Zeolite process for the removal of hardness of water. Discuss its merits over Lime-soda process.

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Explain the Zeolite method of water softening in detail.

Ans.

Regeneration of true exhausted Zeolite bed: When the softening process is continued for longer time, the Zeolite is completely converted in calcium and magnesium Zeolite (CaZ and MgZ) and it stops to further soften water, it gets exhausted. At this stage the supply of hard water is stopped and exhausted Zeolite is regarded by treating it with 10% NaCl solution. This whole process involved alternate cycle of softening and regeneration.

Merits of Zeolite process

1.      Hardness of water is almost completely removed.

2.      Equivalent used occupies small space.

3.      There is no damage of formation of sludge in treated water.

4.      Process automatically adjusted itself for variation in hardness of incoming water.

Demerits:

1.      The process only replaces Ca⁺² and Mg⁺² by sodium ion, but leaves all other ions as such as treated water.

2.      Turbid water, mineral acid water and coloured water containing Mn⁺² and Fe⁺² cannot be treated efficiently.

3.      Treated water contains more sodium salts.