NORT SUR ERDRE Les Mares Noires Wastewater Treatment Plant, Nort-sur-Erdre, France

NORT SUR ERDRE Les Mares Noires is a wastewater treatment facility located in Nort-sur-Erdre, a commune in the Loire-Atlantique department of Pays de la Loire, France. The plant serves a population equivalent of 5,567 and has a designed capacity of 6,000 cubic meters per day, with an average discharge volume of 993.14 cubic meters per 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 (5,000-10,000 p.e.) are required to provide secondary treatment, but the plant's advanced level indicates compliance with stricter standards for sensitive areas or local environmental requirements. The treated effluent is discharged into the local watershed, which ultimately drains into the Erdre River, a tributary of the Loire River. The Loire flows into the Atlantic Ocean near Saint-Nazaire. The plant plays a key role in protecting the Erdre and Loire rivers from nutrient pollution, supporting aquatic ecosystems and downstream water quality.

The plant discharges into the Erdre River, which flows southward to join the Loire River near Nantes. The Loire is one of France's major rivers, supporting diverse fish populations and migratory species such as Atlantic salmon. The watershed includes agricultural and urban areas, making nutrient removal critical to prevent eutrophication in the Loire estuary and coastal waters. The plant's advanced treatment helps maintain ecological balance in this sensitive river system.