Collombey-le-Grand (VS) WWTP

28.09.2021

Nowadays, the Collombey-le-Grand WWTP that was built in 1979 is often overloaded, leading to discharge norms being exceeded on a number of occasions. Furthermore, the original electromechanical equipment of the wastewater treatment plant, has reached its maximum service life and needs to be replaced. HOLINGER AG is the general planner for this project. The Lausanne branch is responsible for the main project and construction management as well as for the implementation planning of the E/I&C equipment and the expansion work. The Sion branch is responsible for civil engineering.

Commissioning is now in progress for Phase 1, which included new stages of mechanical pre-treatment, activated sludge biology, sludge treatment and a biogas feed into the natural gas network.

Phase 2 begins in mid-September with the dismantling of the old WWTP, followed by the renovation of the primary clarification basin, the construction of the anoxia basin and the construction of a new plant building. Finally, the project includes the conversion of the secondary clarifier into a rain basin.

Commissioning will end once we finish the relocation of the discharge point to the Rhone. A gravity pipeline will be installed as the original discharge area suffered from a low level of dilution of micropollutants.