Wastewater treatment involves several stages to manage water discharged from homes and industries. It includes preliminary treatment to remove large objects, primary treatment using sedimentation to remove solids, secondary treatment using bacteria to remove organic waste, and tertiary treatment using methods like UV light or ozonation to further disinfect water before discharge or reuse. The goal is to reduce threats to water sources by eliminating smells, removing solid content, and destroying disease-causing microorganisms.

1. Wastewater
Treatment
By Nathiyadevi K

2. Wastewater Treatment
Purpose:
To manage water discharged from homes,
businesses, and industries to reduce the
threat of water pollution.
• To eliminate offensive smell.
• To remove solid content of the sewage
• To destroy the disease causing
microorganism

3. Wastewater Treatment
 Preliminary treatment
 Primary treatment
 Secondary treatment
 Tertiary treatment
 Sludge (bio-solids) disposal

4. Preliminary Treatment
- removes large objects and non-
degradable materials
- protects pumps and equipment from
damage
- bar screen and grit chamber

5. Preliminary Treatment
Bar Screen
- filters large objects that have gotten into
sewer system such as bricks, bottles, pieces
of wood, etc.

6. Preliminary Treatment
Grit Chamber
- removes rocks, gravel, broken glass, etc.
Mesh Screen
- removes diapers, combs, towels, plastic
bags, syringes, etc.

7. Preliminary Treatment

8. Primary Treatment
• a physical process
• wastewater flow is slowed down and
suspended solids settle to the bottom by
gravity
• the material that settles is called sludge or
bio-solids.

9. Primary Treatment

10. Secondary Treatment
 It is biological process.
Biodegradable organic waste are removed by
aeration bacteria.
It removes 90% of the oxygen demanding
waste.
Done by Trickling filter or Activated sludge
process

11. Trickling Filter


12. Activated sludge Process

13. Wastewater Treatment
From secondary treatment on the trickling
filter water flows to the final clarifiers for
further removal of sludge.
The final clarifiers are another set of
primary sedimentation tanks.
From the final clarifiers the water is
discharged back to the Mississippi River.

14. Wastewater Treatment
The final clarifiers
remove additional
sludge and further
reduce suspended
solids and B.O.D.

15. Tertiary Treatment
Disposal of Sludge or Biosolids
-- the sludge undergoes lime
stabilization (pH is raised by addition
of lime) to kill potential pathogens
-- the stabilized sludge is land applied
by injection into agricultural fields

19. • Damage the genetic
structure of bacteria,
viruses and other
pathogens.
• Wavelength-254nm
• Advantages: no chemicals
are used
• water taste more natural
• Disadvantages: high
maintenance of the UV-
lamp
UV light radiation

21. • Oxidized most pathogenic microorganisms
• Advantages: safer than chlorination
fewer disinfection by-product
No residual…ozone degrades to
oxygen, O2
• Disadvantage: high cost, need
Equipments and electricity

22. Wastewater Treatment
Disposal of Sludge or Biosolids
-- landfill disposal discontinued to the
threat of leachate
-- incineration discontinued because of
the ineffectiveness and cost

23. Wastewater Treatment
The wastewater plant lab conducts
a number of measurements and
tests on the water.
suspended solids temperature
B.O.D. nitrogen
pH phosphorus

24. What can be effluent used for?

25. Wastewater Treatment
In addition to test performed at
the wastewater lab, an off-site
contract lab performs additional
tests
heavy metals priority pollutants
W.E.T (Whole Effluent Toxicity) tests