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Technological Routes for Energy Recovery from Sewage

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Sewage is a potent waste from urban sources generated in bulk quantities, suitable for energy generation. However the source is highly diluted in nature and materials attain complexity during its course of travel from multiple points of origin. Therefore it demands for primary treatments in centralized treatment facilities which involve segregation of inerts from sewage solution as they are beyond the scope of energy generating technologies and concentration of diluted sludge, rich in organics as suspended, dissolved and volatile bio-solids from effluent water.

This pre-processed sludge mixture can be utilized as such with anaerobic digestion technology but requires additional moisture reduction for use in pyrolysis, gasification and incineration technologies.

To assess the options for energy recovery from sewage the following parameters have to be considered.

      Physical properties

      Chemical properties

  • Mass of sludge
  • Density of sludge
  • Sludge settlement
  • Moisture
  • Solubility and volatilization of sludge organics
  • Temperature & Pressure
  • Reaction time
  • Efficiency of machineries
  • Concentration of metabolizable organics, pH
  • Toxicants and Xenobiotics
  • Concentration of non hydro-carbonaceous materials
  • Activity of microbial catalysts and associated factors
  • Activation energy
  • Calorific value of fuels
  • Load of microbes in biomethanation





Soluble solids(SS)

150-250 ppm

 Biological Oxygen Demand (BOD)

200-400 ppm

Chemical Oxygen Demand (COD)

400-750 ppm

Oil and Grease

15-30 ppm

Total Dissolved Solids (TDS)

500-800 ppm












 The primary technological options available for treating sewage are highlighted in the figure below



Technology Options for Energy Recovery from Waste

Technological Routes for the Recovery of Energy from MSW

Technological Routes for Energy Recovery from Sewage

Technological Routes for Energy Recovery from Fecal Sludge


India Waste to Energy