The document discusses methods for chlorination and small-scale purification of water, detailing processes like boiling, chemical disinfection, and filtration. It emphasizes the importance of achieving a target of 0.5 mg/l of free residual chlorine, provides guidelines for using bleaching powder and tablet chlorination, and explains the limitations and effectiveness of various purification methods. Additionally, it outlines calculations for determining water volume and the amount of chlorine needed for disinfection.

1. Dr PRANAV MK
MPH SCHOLAR
Amrita institute of medical sciences , KOCHI
CHLORINATION &
SMALL SCALE PURIFICATION OF WATER

2. a) large scale purification of water.
b) Small scale purification water.

3. c) Disinfection

4. hypochlorous acid

5. turbidity.
• Chlorine demand
• Contact period

6. • Break point the point at which the chlorine demand of water is met

8. Chlorine gas , chloramine, perchloron

11. SMALL SCALE PURIFICATION OF WATER

12. BOILING
CHEMICAL
DISINFECTION
FILTRATION
ULTRAVIOLET
IRRADIATION
MULTISTAGE
REVERSE
OSMOSIS
PURIFICATION

13. • To be effective : Rolling boil : 10-20 minutes
• It kills all the bacteria ,spores , cysts and ova – also removes hardness – by
driving off carbon dioxide and precipitating calcium carbonate
• Boiled water should be stored in same container – to avoid contamination

14. Bleaching
powder
Chlorine
solution
High test
hypochlorite
Chlorine tablets
iodine Potassium
permanganate

15. • Bleaching powder or chlorinated lime (caocl2) : white amorphous with pungent
smell of chlorine.
• Contain 33 % available chlorine – when freshly made.
• Rapidly loss of chlorine content upon exposure to – light , air, moisture.
• Target : free residual chlorine of 0.5 mg/L at the end of one hour.

16. • May be prepared from bleaching powder
• Similar properties to bleaching powder

17. • HTH is a calcium compound with 60-70% available chlorine .
• More stable than bleaching powder

18. • Various types available. (trade names VIZ, halazone tablets.)
• .05 g tablet sufficient to disinfect 20L of water.

19. • May be used for emergency disinfection of water
• 2 drops of 2 % ethanol solution of iodine – required for 1 L of clear water.
• Contact time 20-30 minutes
• Disadvantage :
 high cost
 Physiological active ( thyroid )

20. • No longer recommended for disinfection of water
• Kills vibrio cholerae , but ineffective against other pathogen
• Disadvantage :
• Alters – colour , taste , smell of water

21. Using ceramic
filters
Berkefeld filter
Pasteur
chamberland
filter
Katadyn filter

23. Can be used for :
• To remove bacteria , but not viruses
• Only with clean water

24. • A film of water is exposed to UV radiation at 254 nm wavelength.
• The water should be free from :
 Turbidity
 Suspended /colloidal impurities

25. • Advantages
 Short duration of exposure
 No alteration of taste or odour
 No harmful effects due to overexposure
• Disadvatages
 No residual effect
 Expensive

26. • Used to make water chemically and micro biologically potent :
• By reducing
Total dissolved solids
Hardness
Heavy metals
Pathogens

27. Find
volume of
water in
well
Find
amount of
bleaching
powder
required for
disinfection
Dissolve
bleaching
powder in
water
Deliver
chlorine
solution
into well
Contact
period
Test for
residual
volume

28. • Measure depth of water column (h) in meters.
• Measure diameter of well (d) in meters
• Substitute above value in formula :
• Value (liters) = 3.14*d^2*h * 1000
4
• 1 cubic metre = 1000 litres of water.

29. • Estimate chlorine demand using Horrock’s apparatus
• 2.5 g good quality bleaching powder required to disinfect 1000 liters of water

30. • Place bleaching powder (<100g) in a bucket and make into thin paste.
• Add water and make solution till 3/4th of the bucket.
• Stir the contents well , allow to sediment * 5-10 minutes.
• Transfer the supernatant ( chlorine solution ) to another bucket.
• Discard chalk / lime residue.

31. • Lower bucket containing chlorine solution below water surface.
• Agitate water by violently moving vertically and horizontally several times.

32. • Allow a Contact Period between the Chlorine and Water
- Contact period of 1 hour allowed before anyone is permitted to draw water from
the well

33. • Orthotolidine Arsenite Test is then performed at the end of one hour contact
period.
• This is done to check the level of free residual chlorine
• OTA test : if free residual chlorine level is < 0.5 mg/L : repeat chlorination
process