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L-20Sludge Disposal Methods
Industrial Waste treatment
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.
A] SLUDGE TREATMENT Thickening Conditioning Dewatering Drying Incineration Disposal
1. Thickning Reduces moisture content of sludge,
thereby reducing volume of sludge. Three types of thickening1. Gravity thickening2. Air floatation3. Centrifugation
Gravity Gravity Thickening
2. Conditioning Conditioning improves the drainability
of digested sludge. Methods adopted 1. Elutriation (involves passage of air to 1. Elutriation (involves passage of air to
separate particles)2. Chemical conditioning (addition of
coagulants)3. Freezing etc.
3. Dewatering
Purpose is to reduce volume ofsludge and increase concentrations ofbiosolids.biosolids.
Dewatering can be achieved on sanddrying beds.
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
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 used vacuum, 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
Sludge drying beds
Sludge drying beds
4. Heat drying
Reduces water content Temp @ 350oC Process carried out in kiln. Dried sludge used as soil conditioner
Heat drying unit
Sludge Reuse or Disposal OptionsIncineration 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
SludgeIncineration:
MultipleMultipleHearth
Fluidized bed sludge incineration
Incinerator
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
Sludge Reuse or Disposal OptionsSurface disposal trench, waste pile, lagoon biosolids remain longer than 2 years surface impoundment surface impoundment dedicated disposal sites
Disposal site
Sludge Reuse or Disposal OptionsLand 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
Land Application
Sludge filling station
Land disposal of sludge
Disposal into the sea
Sludge Lagooning
Sludge lagoons
Economic Aspects
Waste to Wealth
INCORPORATING BIOMASS INTO BRICKSINCORPORATING BIOMASS INTO BRICKSINCORPORATING BIOMASS INTO BRICKSINCORPORATING BIOMASS INTO BRICKS
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
Theory questions Write detailed note on 1. Sludge disposal 2. Sludge drying bed 2. Sludge drying bed