Lecture notes of Industrial Waste Treatment (Elective -III) as per syllabus of Solapur university for BE Civil Prepared by Prof S S Jahagirdar, Associate Professor, N K ORchid College of Engg and Tech, Solapur

1. L-20
Sludge Disposal Methods
Industrial Waste treatment

3. Definition
• “Sludge” is defined as the residual material
removed from wastewater treatment
facilities.
• A new term, “biosolids,” suggests the• A new term, “biosolids,” suggests the
beneficial usage of sludge.
• The definition of “biosolids” is now
accepted as those primarily organic solid
products produced by wastewater treatment
processes that can be beneficially recycled.

4. A] SLUDGE TREATMENT
• Thickening
• Conditioning
• Dewatering
• Drying
• Incineration
• Disposal

5. 1. Thickning
• Reduces moisture content of sludge,
thereby reducing volume of sludge.
• Three types of thickening
1. Gravity thickening
2. Air floatation
3. Centrifugation

6. GravityGravity
Thickening

7. 2. Conditioning
• Conditioning improves the drainability
of digested sludge.
• Methods adopted –
1. Elutriation (involves passage of air to1. Elutriation (involves passage of air to
separate particles)
2. Chemical conditioning (addition of
coagulants)
3. Freezing etc.

8. 3. Dewatering
• Purpose is to reduce volume of
sludge and increase concentrations of
biosolids.biosolids.
• Dewatering can be achieved on sand
drying beds.

9. Sludge Processing
• Dewatering - removes liquids
• Drying beds
• solids concentration up to 40%
• used for well digested, stabilized residuals• used for well digested, stabilized residuals
• Centrifuges
• solids concentration 20 to 40 %
• rotates liquids at high speeds & spins the
water away

10. Sludge Processing
• Vacuum Filters
• solids concentration 15 to 30 %
• rotating filter media passes through vat of residuals,
residuals coat the filter and water is extracted by
vacuum, polymers may be usedvacuum, polymers may be used
• Pressure filters
• solids concentration up to 50%
• series of vertical plates, belts, or frames, water
squeezed out under pressure, solids are retained
between the belts or plates

11. Sludge drying beds

12. Sludge drying
beds

13. 4. Heat drying
• Reduces water content
• Temp @ 350oC
• Process carried out in kiln.
• Dried sludge used as soil conditioner

14. Heat drying unit

15. Sludge Reuse or Disposal Options
Incineration
• burning sludge at high temperatures in furnace
• volume is reduced
• ash is stabilized• ash is stabilized
• requires air permit & pollutant removal
• high operating costs
• complex
• Temp @ 650oC to 750oC

16. Sludge
Incineration:
MultipleMultiple
Hearth

17. Fluidized bed sludge incineration

18. Incinerator

19. Sludge Reuse or Disposal Options
Landfill
• disposal of sludge in a lined landfill
• leachate collection required
• odor potential
• local regulatory requirements
• inexpensive
• Trucking (Transportation) costs

20. Sludge Reuse or Disposal Options
Surface disposal
• trench, waste pile, lagoon
• biosolids remain longer than 2 years
• surface impoundment• surface impoundment
• dedicated disposal sites

21. Disposal site

22. Sludge Reuse or Disposal Options
Land Application
• application of sludge to condition the soil or
fertilize crops / other vegetation
• sprayed or spread on soil surface
• tilled into soil or injected directly below the
surface
• must be applied at agronomic rates, meet
pollutant limits, and pathogen & vector
attraction reduction requirements
• requires 30 days or more of storage

23. Land Application

24. Sludge filling station

25. Land disposal of sludge

26. Disposal into the sea

27. Sludge
Lagooning

28. Sludge
lagoons

29. Economic Aspects

30. Waste to Wealth

32. INCORPORATING BIOMASS INTO BRICKSINCORPORATING BIOMASS INTO BRICKSINCORPORATING BIOMASS INTO BRICKSINCORPORATING BIOMASS INTO BRICKS

33. Objective questions
• 1. Sludge drying beds are used for _________
of sludge.
• 2. ____________ reduces volume of sludge
considerably as compared to other methods.
• 3.Pick out odd one w r t sludge• 3.Pick out odd one w r t sludge
• Biogas recovery, metal extraction, use in
building materials, odour and pathogen

34. Theory questions
• Write detailed note on
• 1. Sludge disposal
• 2. Sludge drying bed• 2. Sludge drying bed