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Municipal sludge treatment

Energy recovery and dehydration of digested sludge

Turning problem waste into an opportunity

A sustainable way of reducing excess sludge volume and making advantage of its intrinsic characteristics is to recover its energy potential and use solar power to dehydrate the residual sludge. Depending on dried sludge composition and local legislation, dehydrated and stabilized sludge can be used as fertilizer or compost.

Energy from sludge

Sludge from wastewater is a valuable energy source. After a first sludge thickening step, our BIOTIM® sludge digestion reactors produce biogas while significantly reducing sludge volume. The treated biogas can be used to generate heat and electric power, reducing the carbon and energy footprint of the wastewater treatment plant.

Up to 70% of the energy needs in a wastewater treatment plant can be recovered from sludge digestion.

Marrakech solar drying
Marrakech solar drying

Reducing digested sludge volume

In regions where the sun is abundant, our HYDROGONE Greenhouse Drying solution makes use of solar energy for sludge dehydrating. In the Fez and Marrakech wastewater treatment plants for instance, automated robots stir digested sludge in large greenhouses relying on thermal heat to increase dry solids concentration.

In both plants, the sun-dried sludge reduces transportation costs dramatically. The dried sludge can be recovered in the construction industry or as for co-incineration.

Both wastewater treatment plants are amongst the most sustainable in the African continent.

Sludge conditioning

The Waterleau sludge stabilization solution uses lime for sludge reuse as fertilizer or compost in agriculture or horticulture. The lime improves evaporation and locks the heavy metal ions in an insoluble form, eliminating pathogens, avoiding fermentation and the release of unpleasant odours.

Relevant Cases

Protecting the environment in Fez

Protecting the environment in Fez

The Fez municipal wastewater treatment plant returns safe discharge water into the river bed.



The new Kenitra municipal wastewater treatment plant turns wastewater into safe irrigation water. Half of the plant's energy needs is recovered from sludge digestion.

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