Wastewater and its treatment

1. Wastewater
Treatment
Aqsa

2. “Thousands
have lived
without
love, not one
without water”
“Auden”

3. Wastewater
Water that has been affected or
contaminated by human activities in any
way.
It includes substances such as human
waste, food scraps, oils, soaps and
chemicals.
Different sources.
Domestic and nondomestic

4. Types of Wastewater

5. Wastewater composition
•Organic matter Heavy metal
•Nutrient Pathogen
•Sand
•Suspended Solid
•Salt
•Stone

6. Wastewater constituents
Organic matter
1. Sugar
2. Protein
3. Fat

7. Suspended matter in sewage
1. Food left over
2. Sand particles
3. Fecal matter

8. Waste water composition

9. Impact of untreated sewage discharge

10. Purpose
To speeding up the
natural purification
process.
Reduce the BOD
(Biological Oxygen
Demand).
Protecting public
health.
Recycling and
recovering.
Prevent
Eutrophication
Remove
pathogenic
organism

11. General steps in
Wastewater Treatment
Preliminary Treatment
Primary Treatment
Secondary Treatment
Tertiary Treatment

12. Overview of Wastewater Treatment

13. Steps of Wastewater treatment
1. Collection of water
2. Preliminary Treatment
3. Primary treatment
4. Secondary Treatment
5. Tertiary Treatment
6. Sludge Treatment
7. Discharge

14. Preliminary Treatment
Physical Treatment and clarification of large particles.
•Screening
•Grit chamber

15. Primary Treatment
Physical separation of small particle
•Settlement tank
•Gravitational force & Prevent damage
•25-50%BOD
•50-70%Suspended solids
•65% oil and grease
•Sludge and scum

16. Secondary Treatment
•Mainly liquid part
•Biological treatment
•Remove organic matter
•Aeration chamber &
secondary clarifier
•Activated Sludge

17. ii. Trickling Filter

18. Tertiary treatment
•Chemical treatment
•Kill microbes
•Gravity filters and membranes
•Chlorination

19. Advance treatment

21. Treatment overview
Functional units
•Physical treatment
• Chemical treatment
• Biological treatment
 Targeting specific groups of pollutants

22. Physical methods
Screening Grit chamber
Fat and grease
removal
Sedimentation Adsorption

23. Screening
•First step
•Removal of floating solids
•Rags, paper, plastic
•Prevent damage and blockage
•Coarse screening and fine screening

24. Grit chamber
•Is long narrow or circular tank
•Remove sand, eggshell, coffee ground
•Putrescible material
•Prevent channel clogging
•And pump damage

25. Fat and grease removers
• Passing sewage small tank
•Fat collected through skimmers

26. Sedimentation
•Removes particles by gravity.
•Accumulated solids, or sludge.
•Removed periodically from bottom.
• Coagulants are added to the
•Aid in settling.

27. Adsorption
•Remove compounds from industrial wastewater.
•Removal or low concentrations of non-degradable organic
compounds
•Adsorption takes place when molecules in a liquid bind
themselves to the surface of a solid substance.
•Active carbon is by far the most commonly used adsorbent.

28. Chemical methods
1.Neutralization
2.Flocculants
and coagulants
3.Oxidation
4.Ion exchange 5.Ozonation 6.Disinfection

29. Neutralization
•Industrial water
•Adjust the pH value
•Treat waste water
containing metals
•Acid+ Base= Neutralization.
•Collection.

30. Flocculants and coagulants
•Solid removal, water clarification,
lime softening , sludge thickening,
and solid dewatering.
• Neutralization
• Inorganic or organic coagulant
•Used to treat water for suspended
solids removal.
.

31. Contd….
1.Flocculants
i. Gather destabilize particles together
ii. agglomerate and
iii. drop out of solution
2. Low, medium and high weight molecular polymers

32. Oxidation
•Oxidation reduces the BOD of waste water
•Reduce the toxicity.
•Widely used for disinfection.

33. Ion exchange
•Use to soften hard water
•Calcium and magnesium
•Sodium ions
•Dissolved sodium chloride salt,
or brine
•Exchange of ions

34. Ozonation
•Disinfection of drinking water
•Removal of effluents from
wastewater treatment plant is
a process called ozonation
•Degradation of organic
and inorganic pollutants.

35. Disinfection
•Reduce the number of microorganisms
•For the later use.
•Depends on
i. The quality of water treated
ii. Type of disinfectant used
iii. Disinfectant dosage

36. Biological methods
• Activated Sludge Process
• Trickling filters
• Aerated Lagoons
• Oxidation Pond
1. Aerobic
Treatment
2.
Anaerobic
Treatment

37. Aerobic Treatment
•Biological process
•Presence of oxygen.
•Rapid & most efficient
•Remove up to 98% of organic contaminants. .
•Remain efficient and stable in all conditions.

38. Types of aerobic treatment
i. Activated Sludge Process
ii. Trickling filters
iii. Aerated Lagoons
iv. Oxidation Pond
Activated sludge process is the most widely used process

39. i. Activated Sludge Process
•A multi-chamber reactor unit
•Use of highly concentrated microorganisms
• Degrade organics and remove nutrients.

40. ii. Tricklingfilters
• Second commonly using type.
•Percolating or sprinkling filters
•Remove compounds such as ammonia

41. iii. Aerated Lagoons
•A treatment pond
•Provided with mechanical aeration
•To promote the biological oxidation.
• The effluent may be reused
•Settled sludge requires a
further treatment.

42. iv. Oxidation Pond
•Involve an interaction between bacteria, algae and other
organisms
• Feed on the organic matter from primary effluent.
•Productive
•Slow and requires large areas of land.

43. Anaerobic Treatment
•Effectively treat high strength waste water
•Employs organisms that function in the absence of oxygen
•Sludge degradation and stabilization.
• Converts about 40% to 60% of the organic solids to methane
(CH4) and carbon dioxide (CO2).

44. Wastewater treatment system in Pakistan
•Only 1% of the
domestic and industrial
wastewater receives
treatment.
City Waste water plants
Islamabad Three wastewater treatment plants, only
one functional
Lahore some screening and grit removal systems,
but they are hardly functional
Karachi Two trickling filters, effluents generally
receive screening and sedimentation
Faisalabad There is a wastewater treatment plant, in
which wastewater receives primary
treatment.
Rural areas Nonexistent