Sludge digestion

Sludge, the by-product of biological wastewater treatment is also considered as biomass. Energy recovery from sludge is possible through sludge incineration (biomass-to-energy) or by means of sludge digestion (biomass-to-biogas).

Digestion of sludge

Waterleau has developed a complete set of anaerobic reactors for the production of new energy from bio-effluents and biomass. The methane generation is a key advantage of the anaerobic process. The methane can be used to generate heat and electric power in cogeneration units while reducing the carbon footprint and greenhouse emissions of the wastewater treatment plant.

After sludge digestion, the digestate can be stabilized for landfill or used as fertilizer, depending on its composition and local legislation. An alternative is to further mechanically dewater the sludge prior to thermal drying and incineration.


  • Reduction of sludge volume
  • Production of biogas available for heat and electric power generation
  • Reduction of greenhouse gases


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