BIDOS INTERCOMMUNALE Wastewater Treatment Plant, Oloron-Sainte-Marie, France

BIDOS INTERCOMMUNALE is an advanced wastewater treatment plant located in Oloron-Sainte-Marie, within the Pyrénées-Atlantiques department of Nouvelle-Aquitaine, France. The facility serves a population equivalent of 3,360 and has a designed capacity of 4,100 cubic meters per day, with an average discharge volume of approximately 599 m³/day. The plant employs advanced treatment processes, which go beyond secondary treatment to remove nutrients and other pollutants. Under the EU Urban Waste Water Treatment Directive (91/271/EEC), agglomerations of this size (under 10,000 population equivalent) are generally required to provide secondary treatment, but the advanced level here indicates a higher standard, likely due to the sensitivity of the receiving environment. The treated effluent is discharged into local waterways that ultimately drain into the Atlantic Ocean via the Gave d'Oloron and the Adour River. The plant plays a key role in protecting the water quality of these rivers, which support diverse aquatic life and are important for regional ecology and recreation.

The plant discharges into the Gave d'Oloron, a tributary of the Adour River, which flows into the Bay of Biscay (Atlantic Ocean). The watershed supports diverse aquatic ecosystems, including migratory fish species such as salmon and eels. The advanced treatment level helps minimize nutrient loading and protect downstream water quality in this ecologically sensitive region.