The process for supply water treatment for drinking water is given in a brief way

1. Presented by:-
Suhail Ameer Alvi
Department Of Civil Engg.
Aligarh Muslim University
SUPPLY WATER
TREATMENT

2. INDIAN STANDARD FOR DRINKING WATER
Parameter Desirable Tolerable
Turbidity (NTU) < 10 25
Colour (Hazen Scale) < 10 50
pH 7.0 - 8.5 6.5 – 9.2
Total Dissolved
Solids (mg/L)
500 – 1500 3000
Total Hardness
(mg/L as CaCO3 )
200 – 300 600
Chlorides (mg/L ) 200 - 250 1000
Fluorides (mg/L) 0.6 – 1.2 1.5
Sulphates (mg/L) 150 – 200 400
Nitrates (mg/L) 45 45

3. SUPPLY WATER TREATMENT
The motive for treatment of the supply water is to
provide a good quality water that reaches all the
health demands of the peoples & the chemical
requirements of industries.
• Process of Treatment:
Screening Aeration Sedimentation Coagulation
& Flocculation
Miscellaneous Disinfection Softening Filtration

4. Screening:
• Screens are used to remove large floating bodies.
• As time passes, clogging occurs so screens are cleaned
regularly to maintain constant design velocity.
• Screens are generally provided inclined due to racking
mechanism & inclination gives more flow area.
• Screens:
1.Fine Screens (<10mm)
2.Coarse or Bar Screens (20mm-10mm)
• Angle of inclination of screen is 30∙-60∙

5. Aeration:
• Air is passed to increase the amount of Oxygen in water.
• As O2 increased amount of dissolved gases is decreased.
• CO2 decreased and hence the acidity, H2S decreased and
hence the smell.
• Color producing Fe & Mn are oxidized, and they can be
removed as their precipitation occurs.
• Oxidation of microbes leads to removal of microbes.
Methods of Aeration-
1.Cascade Method 2. Tray Tower Method 3. Air Diffusion
Method 4. Spray Nozzle Method

6. Tray Tower MethodCascade Method
Air Diffusion Method Spray Nozzle Method

7. Sedimentation:
• Particles are removed using graviometric separation.
• Flow Velocity; Vf is reduced to remove suspended solids.
• Settling Velocity; Vs α Weight of particle.
• Sedimentation Tank-
1.Fixed Type or Quiscent Type- Vf=0
2.Continuous Flow Type- Vf≠0
• In Fixed Type the water is kept store for the detention time.
• Continuous Flow Type is generally used along with the
rectangular shape.
• Particle for design is considered which enters from the top
of Sedimentation tank.

8. …contd.
• Design particle travels vertical distance “H” & horizontal
distance “L”.
• Settling Velocity; Vs of particle is given by-
𝑉𝑠 =
4
3
𝑔.𝐷(𝐺−1)
𝐶 𝑑
g= acc. due to gravity
D= diameter of particle
Cd = coeff. Of discharge
G= sp. Gravity of particle
Rectangular Sedimentation Tank

9. …contd.
Sedimentation Unit

10. Coagulation & Flocculation:
• Smaller suspended particles that can’t be remove from
sedimentation are removed here.
• It consists of four units; Feeding device, Mixing device,
Flocculation tank & Sedimentation tank.
1. Feeding Device-It controls the rate of addition of coagulant.
Feeding can be dry feeding or Wet feeding.
2. Mixing Device-Coagulant added are well mixed here. Mixing
can be done by Flash mixers or in Mixing basin.
3. Flocculation Tank-In Flocculation tank impellers rotate to
form flocs of particles.
4. Sedimentation Tank- Flocs produced are removed here.

11. …contd.
• In Flocculation tank, there is Tapered flocculation.
• There may be various types of coagulant used like Alum,
Copperas, Chlorinated Copperas & Sodium Aluminate.

12. Filtration:
• Particulate matters are removed by passing through a media
having small size opening.
• Filters may be of two types namely Slow Sand (Biological)
Filters and Rapid Sand (Mechanical) Filters.
• Slow Sand filter consists of concrete basin containing sand,
gravel & stones.
• Schmutzdecke removes
bacteria and holds
back organic matter.
• Scrapping of layer is
done to clear filter bed.
Slow Sand Filter

13. …contd.
• Rapid Sand filters are also of two types:
1. Gravity / Open Type- Flow is in under gravity.
2. Pressure / Closed type- Flow is in under pressure.
• In Rapid sand filter rate of filtration is more than that of Slow
sand filter.
• In Rapid sand filter cleaning of filter bed is done by
Backwashing.
• In Filtration there is Laminar flow while in Backwashing there
is Transitional flow.
• 5% of treated water is kept store for backwashing.

14. Softening:
• Hardness of water is removed by Softening the water.
• Hardness is due to Multivalent Cations (Ca+2 & Mg+2 mostly).
• Hardness- 1.Carbonate or Temporary hardness
2.Non-Carbonate or Permanent hardness
Methods of Removal-
1. Boiling
2. Lime Soda Method
3. Zeolite Method
4. Ion Exchange Method
Boilers

15. …contd.
1. Boiling-
• On boiling only temporary hardness due to Ca is removed
not of Mg.
2. Lime-Soda Method-
• By adding Lime the Temporary hardness due to Ca & Mg is
removed & Lime converts the permanent hardness due to
Mg into Permanent hardness due to Ca.
• After Lime, Soda is added to remove permanent hardness
due to Ca.
3. Zeolite-
• Zeolites are complex salts of Na, Al & Si and are available in
the form of porous beds.

16. …contd.
• Exhausted Zeolites are regenerated using 5% Brine solution.
• Fe/Mn permanently exhausts the zeolites.
4.Ion Exchange Method-
• Hydrides of Synthetic Resins are used to remove hardness.
• Regeneration of Resins
is done using HCl.
• Ion Exchange produces
zero hardness water.
Zeolite Method of Softening

17. Disinfection:
• Disinfection / Sterilization are used for removal of pathogens.
• Oxidants are used to kill microbes.
• Types Of Disinfection-
1.Physical Methods-
a. Boiling
b. U.V. Rays
2.Chemical Methods-
a. Ozone (O3)
b. Iodine & Bromine- Available in pills & tablets.
c. Potassium Permanganate (KMnO4)- Weak Oxidant
d. Chlorination

18. …contd.
• Chlorination is most widely used method.
Break Point Chlorination- Breakpoint is the point at which
oxidation of organic matter & microbes killing is
completed.
1-Killing of microbes
2-Increase in residual Cl2
3-Oxidation of organic
matter
4-Accumulation of Cl2

19. Miscellaneous Water Treatment:
• Activated Carbon-
-High absorption capacity
-Used during Filtration & Coagulation
• Desalination-
-Removal of salts
-Evaporation, Freezing,
Electrolysis & RO can
be the methods.
• Copper Sulphate-
-Used for killing of
Algae.
Desalination By Reverse Osmosis

20. Plants in Uttar Pradesh
Major plants in India

21. References:
• https://www.youtube.com/channel/UCj3uro8sUcAMj5gEEw9u
-FA
• https://youtu.be/E_oa06Eq5s8
• https://youtu.be/zBKLE1ImS_s
• https://youtu.be/6wXBWfhnWMs
• https://youtu.be/Nbm0UDWljK0
• https://youtu.be/dENsJR1kk04
• https://youtu.be/F6Nl09LeHPI
• https://youtu.be/Fchroj2MDKQ
• https://youtu.be/mDIpsznj2o8
• https://youtu.be/LXXGbgpU3Vc
• https://youtu.be/sW5j775s_hw

22. THANK YOU!