This ppt gives basic knowledge of purification of water and its treatments such as screening, aeration, sedimentation, filtration and disinfection.

1. PURIFICATION OF WATER

2. Screening: To remove floating matter of large
size which will choke up small pipes.
A. According to size of openings:
a. Coarse screens
b. Medium screens
c. Fine screens
B. According to condition of screens:
a. Fixed screens
b. Movable screens
c. Moving screens

3. Aeration: Exposing large surface of water to
atmospheric air.
• Objects:
1. To remove volatile substances & gases causing bad
taste & odour.
2. To increase oxygen level in water for imparting
freshness.
3. To oxidize Fe & Mn so that these can be precipitated
& agitated.
4. To destroy bacteria to some extent by agitaton.

4. Methods of aeration
a. By using fountains, spray nozzles

5. Methods of aeration
a. Gravity or free fall aerators:
• Cascade aerators:
Circular type Straight type

6. Methods of aeration
a. Gravity or free fall aerators:
• Inclined apron aerators:

7. Methods of aeration
a. Gravity or free fall aerators:
• Trickling beds or multiple trays:

8. Methods of aeration
a. Gravity or free fall aerators:
• By air diffusion:

9. Sedimentation: suspended particles settle
down under the action of gravity
• Plain sedimentation:

10. Sedimentation with coagulation
JAR TEST APPARATUS

11. Sedimentation with coagulation
CLARI-FLOCCULATOR

12. Filtration: Process of removing particulate & bacterial
impurities by passing water through porous medium.
• Theory of filtration:
1. Mechanical straining
2. Sedimentation
3. Biological metabolism
4. Electrolytic charges

13. Slow sand filter

14. Rapid sand filter

15. Disinfection: killing pathogenic
bacteria from water

16. Chlorination

17. Break point chlorination

18. Water softening: Removing hardness of water
• Zeolite process:

19. References:
• Water supply engg (Volume 1) – S.K. Garg
• Water supply and sanitary Engg – G.S. Birdie,
J.S. Birdie
• Water supply and waste water engg – A.K.
Upadhyay, D. LAl