Saint-Calais Rte de Besse_Braye Wastewater Treatment Plant | Pays de la Loire, France

The Saint-Calais Rte de Besse_Braye wastewater treatment plant is located in the commune of Saint-Calais, within the Sarthe department of the Pays de la Loire region in northwestern France. The facility serves a population of approximately 4,712 residents and operates with advanced treatment capabilities, ensuring high-quality effluent before discharge. As an advanced treatment plant, it goes beyond secondary biological processes to remove nutrients such as nitrogen and phosphorus, which is particularly important for protecting sensitive water bodies. The plant has a designed capacity of 8,425 cubic meters per day and currently treats an average daily volume of 840.61 cubic meters, indicating ample reserve capacity for future growth. Under the EU Urban Waste Water Treatment Directive (91/271/EEC), plants serving agglomerations of this size are required to provide secondary treatment, but Saint-Calais exceeds this standard with tertiary-level processes. The treated effluent is discharged into the local river system, which ultimately drains into the Loire River basin. The Loire is one of Europe's last wild rivers and supports diverse aquatic ecosystems, including migratory fish species. The plant's advanced treatment helps reduce nutrient loading and protect downstream water quality in this ecologically significant watershed.

The plant discharges into the Sarthe River, a tributary of the Maine River, which flows into the Loire River before reaching the Atlantic Ocean. The Loire basin is a critical habitat for species such as the European eel and Atlantic salmon. Advanced treatment at this plant helps minimize eutrophication risks and supports the ecological health of the downstream river system.