The Largest Sludge Drying Plant In France


SUEZ ENVIRONNEMENT's subsidiary Degrémont has set up the largest sludge drying plant in Valenton, France.

The extension of the Valenton wastewater treatment plant is coupled with several innovations such as
the sludge tank covered by a dome in order to isolate odours and evacuation of the dried sludge by train and not by truck make the Valenton plant a model of sustainable development.


The new sludge re-use unit has been equipped with 5 centrifugal machines integrated in a new dehydration workshop, scaled to process 4,200 m3 of sludge a day. Sludge from Valenton can be re-used in several ways:


  • Agronomic Reuse: The complementation unit on the site will be capable of producing 5,000 tons of organomineral products. The batches of pellets compliant with agricultural re-use will be introduced into a specific mixer to homogenize them with fertilizing elements (nitrogen, potassium) proportioned according to the needs of the crops.
  • Energy Recovery On-site: With an annual rated capacity of 36,660 tons of dry sludge material, a reactor will transform all the organic material into synthetic gas. Recovery of the synthetic gas produced and the biogas resulting from the digestion of part of the sludge will cover 80% of the drying requirements in terms of thermal energy. The plant will therefore use 60 to 70% of its waste to produce its own energy.
  • Energy Recovery Off-site: Dried sludge could be used to outsource the recovered energy (energy resold to the French electricity board (EDF), neighbouring cement works, etc.