MARQUION Wastewater Treatment Plant, Marquion, Hauts-de-France

MARQUION is a wastewater treatment plant located in Marquion, a commune in the Pas-de-Calais department of Hauts-de-France, France. The plant serves a small population of 133 residents and is part of the region's municipal wastewater infrastructure. The plant provides secondary treatment, which is the standard biological treatment required under the EU Urban Waste Water Treatment Directive (91/271/EEC) for agglomerations of this size. The designed capacity of 5,000 m³/day indicates the plant is built to handle peak flows, with current discharge volume at 23.73 m³/day. The treated effluent is discharged into local watercourses that ultimately drain into the Scheldt River basin, flowing north toward the North Sea. The plant plays a role in protecting the region's water quality and supporting the ecological health of downstream aquatic environments.

The plant discharges into the Scheldt River basin, which flows through northern France and Belgium before reaching the North Sea near Antwerp. This watershed supports diverse aquatic life and is an important migratory corridor for fish. The region's agricultural landscape means the plant helps mitigate nutrient loading into sensitive downstream waters.