This document discusses various forms and methods of chlorination used in water treatment. It describes plain, pre, post, double, and break point chlorination. It also discusses super chlorination and dechlorination. Additional water treatment methods discussed include water softening using zeolite and lime soda processes, defluoridation, electrolysis, and reverse osmosis. Tests to check residual chlorine include orthotolidine, DPD, chlorotex, and starch-iodine tests.

1. Presentation on
“chlorination”
By
Prof. Vilas N Nikam
Sandip Polytechnic, nashik
Email: vilas5151@gmail.com

2. FORMS OF CHLORINE
1. PLAIN CHLORINATION
2.PRE-CHLORINATION
3.POST CHLORINATION
4.DOUBLE CHLORINATION
5. BREAK POINT CHLORINATION
6. SUPER CHLORINATION
7. DECHLORINATION.

3. 1. PLAIN CHLORINATION
 APPLICATION OF CHLORINE TO THE
WATER AND NO OTHER TREATMENT IS
GIVEN.
 PLAIN CHLORINATION IS ONLY IN
EMERGENCY PERIOD.
 DOSE: 0.5 mg/l

4. 2.PRE-CHLORINATION
 Application of chlorine to water prior to any
other treatment called prechlorination
 Dosage: 0.10 to 0.50 mg/l

5. 3.POST CHLORINATION
 Application of chlorine to the water after all
treatment is over.
 Dasage: 0.10 to 0.20 mg/l

6. 4.DOUBLE CHLORINATION
 Application of chlorine to the water at more
than one point.

7. 5. BREAK POINT CHLORINATION
 Break point chlorination represents the dosage beyond which any
further addition of chlorine will appear as free residual chlorine.

8. 6. SUPER CHLORINATION
 Application of chlorine beyond the stage of
break point chlorination known as super
chlorination
 Dasage : 5 to 15 mg/l
 Residual chlorine: 1 to 2 mg/l
 If dose of chlone exceeds affect the taste and
odour of water, hence req. dechlorination.

9. 7. DECHLORINATION.
 Dechlorination means removing chlorine from
water.
 This req. after super-chlorination.
 It take care that sufficient residual chlorine
should remains in water( 0.1 to 0.2 mg/l).
 Dechlorinating agent: sulphur dioxide
gas,activated carban, sodium
thiosulphate,sodium sulphate.

10. Test to check residual chlorine
 Orthotolidine test.
 D.P.D. Test.
 Chlorotex test.
 Starch – iodine test.

11. Orthotolidine test.
 This most easy and common test to determine residual chlorine.
 1 ml Orthotolidine solution is added to 100 ml chlorinated water sample.
 The colour formed is noted and value of residual chlorine is determined by
comparing the colour so obtained with standard colours of known chorine
residuals.
 But it gives total value of residue ( free chlorine + combined chlorine).
 Free residual chlorine forms yellow colour during first 5 second.
 While combined residual chlorine forms yellow colour after 5 min.
 Presence of iron, manganese,nitrites greatly affects the yellow colours. So
presence of this substances does not gives correct results.

12. Miscellaneous water treatment
 Water softening: removing of hardness ions of
water is known as water softening. Water
softening ids due to presence of Ca and Mg
two types of hardness.
 Carbonate hardness (temparary hardness)
 Non-carbonate hardness(permanant hardness)

13. Methods of water softening
 Zeolite process.
 Lime soda process.
 Demineralisation process.

14. 1.Zeolite process.
 This is also known as ion exchage process.
 In this process of softening the Ca and Mg from the solution are removed by
on the in exchange material like zeolite or synthetic resins(cation exchange
material).
 The solution from zeolite or synthetic resins are enter into water and Ca and
Mg enter into these material.
 After exhaustion capacity of these materials, these regenrated by addition of
sodium chloride solution.
 Thus resin can put into operation again.
Advantages.
 Sludge is not formed, hence no problem about sludge removal.
 No need of skilled supervision as well as operation.
 We can reduce hardness to zero.
 The process proves economical.

15. Disadvantages.
 Process can not be used for high turbid water.
 Not suitable for water containing Ca and Mg

16. 2.Lime soda process
 In this process, the lime and soda ash are used to removed permanent
hardness from water.
 Hardness is brought down to the level of 3 to 4 degree.
Advantages.
 Corrosion of distribution system is decreased as PH value of treated water is
increased.
 Less quantity of corrosion is req.
 Reduction in mineral content.
 Process is economical and suitable for turbid and acidic water.
 Process is easy and simple.
Disadvantage.
 Large quantity of sludege is formed.
 Skilled supervision is req.

17. Defluoridation techinques
 Process of removing excess quantity of fluoride
is known as defluoridation.
 Permissible limit 1 ppm and rejectionable limit is
2 ppm.
Methods of defluoridation.
1.activated carbon prepared from various material
can be used as defluoridation agent.
2.the water may be allowed to pass through the
filter beds cantaining fluoxide retaining
material.

18. Defluoridation Techniques
 DEFINATION:the process of removing excess
quantity of fluoride is known as defluoridation.
 Permissible limit of fluoride is 1 ppm and
rejectionable 2 ppm.

19. Advanced water treatments
 Electrolysis
 Reverse osmosis

20. Electrolysis
 Dia shows the cation and anion exchange membrane arranged alternatively.
 The saline water is fed to through the manifold in alternate compartments.
 Cations and anions migrate towards the cathode and through cation and
anion exchange membranes resp.leaving the feed depleted in salt while the
neighbouring compartment becomes concentrated.


21. Reverse osmosis
 In this method molecules of water and salt ions are separated by forcing the
salt solution against a semi-permeable membrane which permits the flow of
water through itself but stop the salt.
