HERLIES Wastewater Treatment Plant, Marquillies, Hauts-de-France

HERLIES is an advanced wastewater treatment plant located in Marquillies, within the Lille metropolitan area of Hauts-de-France, France. The plant serves a population of 5,283 and has a designed capacity of 6,833 m³/day, with a current discharge volume of 942.48 m³/day. As an advanced treatment facility, HERLIES goes beyond secondary treatment to remove nutrients such as nitrogen and phosphorus, meeting the stringent requirements of the EU Urban Waste Water Treatment Directive (91/271/EEC) for sensitive areas. This level of treatment is typical for plants in the region, which often discharge into water bodies that feed into the North Sea. The treated effluent from HERLIES is discharged into local waterways that are part of the Scheldt basin, eventually reaching the North Sea. The plant plays a crucial role in protecting the region's water quality, supporting aquatic ecosystems, and maintaining the ecological health of downstream environments.

HERLIES discharges into the Scheldt river basin, which flows through northern France and Belgium before emptying into the North Sea. This watershed supports diverse aquatic life and is an important ecological corridor. The advanced treatment at HERLIES helps reduce nutrient loading, mitigating eutrophication risks in the downstream marine environment.