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Technological Routes of Energy Recovery from Fecal Sludge

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The biological origin of fecal sludge enables it to undergo microbial decomposition in biomethanation technology or an enhanced drying, which permits the usage of thermolytic technologies as gasification, pyrolysis, incineration and super-critical fluid oxidation etc. to produce energy from fecal sludge.


Sludge to biogas

Biomethanation/ Anaerobic Digestion

Sludge to syngas


Sludge to oil


Sludge to heat

Incineration/ Combustion

Sludge to liquids

Supercritical fluid oxidation


 The schematic of the technological routes for generation of energy from fecal sludge is given below.



  • Sludge to liquids is in its nascent stage and can be considered unproven currently.
  • Sludge to heat (incineration) and sludge to biogas (biomethanation) are the only two well established technologies in the context of fecal sludge.
  • Sludge to syngas (gasification) and sludge to oil (pyrolysis) could both be considered to be technically feasible, but their economic feasibility in the context of energy recovery from fecal sludge is yet not established
  • While there are solutions emerging, currently biomethanation / anaerobic digestion is the most prevalent and mature technology for fecal waste to energy in India.
  • The advantages gasification and syngas possess over biomethanation is primarily in their higher energy recoveries – that is, they are more efficient than biomethanation for energy recovery. But this efficiency does not factor in the parasitic energy requirements in both these systems.
  • While both biomethanation and incineration are utilized for energy recovery from fecal sludge worldwide (though most countries predominantly use one over the other), in India biomethanation is the only process commercially established currently.
  • Pyrolysis could be an attractive future alternative as its end products – bio-oil and biochar - could fetch the highest monetizations in the market.


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