The building works on the "Prés Blonds" waste water treatment plant, in the locality of Châlette-sur-Loing, lasted a full 30 months and have increased the waste water treatment capacity from 45,000 to 85,000 population equivalent (p.e.).

The urban waste water produced by the population and local commercial and industrial activities is collected by the agglomeration's sewage network and conveyed to the waste water treatment plant. The waste water undergoes several treatment processes in the plant to make sure that the effluent discharged into the Loing River meets the strictest European standards for environmental protection.

The new facility was built without interrupting operation of the old plant.
All plants in the building that are potential sources of malodorous nuisance have been fully covered.
The plant meets the new European standards applying to the removal of nitrates and phosphates and sludge treatment, and even exceeds the standards applying to the treatment of nitrogen.
The site of the former plant was transformed into a green space at the end of the works.

The waste water treatment plant at Châlette-sur-Loing is part of a policy to restore the quality of the ecosystem in the region.
The processes used in the plant eliminate the pollution containing carbon, nitrogen and phosphorous that is produced by the equivalent of 85,000 inhabitants. The treated water flows back into the Loing River.

Special attention was also paid to the prevention and treatment of odours in order to avoid any nuisance and to offer decent working conditions to the staff.

Odours are eliminated from all the air released by the enclosed and ventilated buildings.