Learn about the comparison between lime-soda and zeolite process for water softening.

Comparison # Lime-Soda Process:

1. Size of Plant:

Bulky and large.

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2. Supervision Required:

Skilled supervision is required for success­ful working.

3. Sludge Problem if any:

Large quantity of sludge is formed which needs to be disposed off by some suitable method.

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4. Post Treatment if Needed:

Recarbonation is needed which if not done will cause in­crustation in pipes of the distribution sys­tem.

5. Results Obtained:

This can produce wa­ter of hardness not less than 50 mg/l. Therefore it is useful for public water sup­plies only.

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6. Removal of Iron and Manganese:

Can remove iron and manganese from wa­ter to some extent.

7. Bactericidal:

There is likelihood of killing of bacteria in this process. This oc­curs when causticity caused by calcium hy­droxide or sodium hy­droxide of 20 to 50 p.p.m is retained in the treated water for a period of about 4 to 5 hours.

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8. pH value of Treated Water:

pH value of water treated by this pro­cess is increased which results in de­crease in corrosion of the distribution sys­tem.

9. Care Needed in Handling Materials:

Careful handling is required because the materials, i.e., lime and soda are corro­sive.

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10. Economy:

Process is economical and it can be easily combined with usual water treatment plant.

11. Hardness which can be Treated:

Excessively hard wa­ters, particularly those which are high in magnesium hard­ness can be treated.

12. Allowable Turbidities in Raw Water:

Highly turbid and acidic waters can be treated.

Comparison # Zeolite Process:

1. Size of Plant:

Compact and small.

2. Supervision Required:

Automatic and easy to operate and no skilled supervision required.

3. Sludge Problem if any:

No sludge is formed and hence there is no problem of its dis­posal.

4. Post Treatment if Needed:

No such post treatment is required.

5. Results Obtained:

Water of zero hard­ness can be obtained. Therefore useful for industrial supplies also.

6. Removal of Iron and Manganese:

Not suitable for water containing iron and manganese, because iron zeolite and man­ganese zeolite may be formed which cannot be reconverted into sodium zeolite.

7. Bactericidal:

Bactericidal effect does not exist in this process.

8. pH value of Treated Water:

pH value of water treated by this pro­cess is not affected.

9. Care Needed in Handling Materials:

Salt solution is re­quired to be handled which does not re­quire much care.

10. Economy:

Process is relatively costly.

11. Hardness which can be treated:

Raw water with hard­ness greater than 800 mg/I cannot be easily and economically treated.

12. Allowable Turbidities in Raw Water:

Highly turbid waters are difficult to be treated because the suspended impurities get deposited around zeolite particles and hence cause obstruc­tion to the working of zeolite.