Sludge treatment

A unit treating the settled material from sedimentation tanks was set up at the Annet-sur-Marne plant at the start of 2004. Iron chloride is added to the settled material collected throughout the water treatment process, to facilitate gravity separation of the sludge and water.
The resulting sludge is stabilized with lime and then compressed in two massive presses that squeeze out the remaining water. The dry sludge is then removed by truck and can be used as capping layers for household-waste landfill sites or as soil improvers. The unit processes 600 cubic meters of sludge per hour.