Surface water treatment involves several steps: (1) intake of water from rivers through screens and grit chambers, (2) addition of chemicals like chlorine, lime, and alum through rapid mixing, (3) coagulation through slow mixing to form and densify flocs, (4) settling of flocs in tanks, (5) filtration through granular materials to remove particles, and (6) disinfection through chlorination to remove pathogens before distribution. Proper treatment is essential to make surface water potable and safe for human consumption.

1. WATER TREATMENT PROCESS
PRESENTED BY -
AYAN HAZRA
&
SAHINSHA BADSHA

2. DEFINITION:The process by which the surface or ground water is
made palatable and potable, so that it will not harm human body is
known as water treatment process.
water treatment plant

3. There are two type of process depending on source of
water.
1. Ground water treatment process.
2. Surface water treatment process.

4. SURFACE WATER TREATMENT
FLOWCHART

5. Intake Structure
 At first water is drawn from river by intake structure. Here screen bar and
grit chamber are provided for removal of coarse particle like plastic bags,
paper and heavy particles.


6. Chemical Addition
 In this process chlorine,lime and alum are added with water by rapid
mixing mechanism.
 It can be performed by creating hydraulic jump and adding chemical at
upstream.
 Baffled chamber may be used.
 By using impeller or injecting compressed air, rapid mixing maybe done.

7. BAFFLED CHANNEL HYDRAULIC JUMP IMPELLER

8.  Chlorine is added with incoming raw water to assist the oxidation of
inorganics and to arrest the biological action . This process is known as pre
chlorination.
 Lime is added to remove the hardness.
 Alum is added in order to remove the turbidity.
 As a result of chemical addition small discrete flocs get generated.

9. Coagulation
 Coagulation is the process of removal o flocs that has been generated in
earlier unit process.
 This process is done by slow mixing so that flocs get agglomareted by Van
der Walls attractive force.
 The aim of this process is to large and densify the flocs so that flocs can
settle easily

10. Settling
 In settling the flocs settle at bottom in settling tank by gravity

11. Clarrifloculator
 This is a sedimentation tank in which arrangement of flocculation is
installed.
 It may be circular or rectangular.
 It has two concentric tank . Inner tank serves as flocculation basin and
outer one as clarifier

12. Filtration:-
It is the process in which water passing
through granular materials is known as filtration.
PURPOSE:
 To remove turbidity,colour ,odour and colloidal particle.
 To remove discrete flocs generated in earlier process.
 Pathogenic bacteria are also removed.

13. Types of filters:
1. Slow sand gravity filters.
2. Rapid sand gravity filters.

14. Slow sand filter:
1. Here effective size of filter sand are between 0.2 to 0.4 mm.
2. The rate of filtration is 100 to 200 lit/hr/m2
3. High initial cost required for both land & material.
4. It is very efficient in removing bacteria but
less efficient in removing colour and turbidity.

15. Rapid sand filter:
1. The effective filler sand range in between 0.35 to 0.5 mm.
2. The filtration rate is 3000 to 6000 lit/hr/squre meter. It’s very high
compare to SSF.
3. Very efficient in removing colour ,turbidity etc.
4. Initial cost is less.

16. Other types:
1. Single medium sand filter.(sand)
2. Dual medium sand filter.(coal-sand)
3. Multimedia sand filter.(coal-silica sand-gravel sand).

17. Disinfection:
 The process of removal water born pathogen is known as disinfection.
 The disinfection may be done by chlorinaton or uv radiation or ozonisation.
 In the treatment plant chlorination is common and easier one.
 But upon reaction with the organics chlorine generates carcinogenic product.
 Hence activated carbon can be used before disinfection .
 It adsorbs the organics in water

18. Conclusion-
 Water treatment process consists of a number of unit processes.
 Each of these process is very important.
 Nowadays a number of advanced techniques has been developed in unit
processes which have not been discussed here.
 Above all the preservation of drinking water is as important as treatment of water.

19. QUESTION ?