Douai Wastewater Treatment Plant: Serving Douai, Hauts-de-France, France

The Douai wastewater treatment plant serves the city of Douai in the Hauts-de-France region of northern France. With a population served of 156,278, it is classified as a large agglomeration under the EU Urban Waste Water Treatment Directive (91/271/EEC). The plant is located along the Scarpe River, a key waterway in the region. As a large agglomeration, the plant is required to provide at least secondary treatment, and if discharging into a sensitive area, tertiary treatment for nutrient removal. The EU directive sets strict standards for such facilities to protect water quality. The plant's design and operation are subject to French national regulations implementing the directive, overseen by local water agencies. The treated effluent is discharged into the Scarpe River, which flows into the Escaut (Scheldt) River and eventually reaches the North Sea. This water body supports diverse aquatic life and is part of a dense river network in the industrial and agricultural region. The plant plays a crucial role in maintaining water quality and preventing eutrophication in downstream ecosystems.

The plant discharges into the Scarpe River, a tributary of the Escaut (Scheldt) River, which flows through Belgium and into the North Sea. This watershed supports diverse aquatic habitats and is influenced by industrial and agricultural activities. The plant's treatment helps protect downstream water quality and the ecological health of the Scheldt estuary.