LONGUEAU SE Wastewater Treatment Plant, Longueau, Hauts-de-France

LONGUEAU SE is a municipal wastewater treatment plant located in Longueau, a commune in the Somme department of Hauts-de-France, northern France. The plant serves a population of about 5,528 and has a designed capacity of 6,300 m³/day, with an average discharge volume of 986.19 m³/day, indicating it operates well below its capacity. The plant provides secondary treatment, which is the standard required under the EU Urban Waste Water Treatment Directive (91/271/EEC) for agglomerations of this size (between 2,000 and 10,000 population equivalent). Secondary treatment typically involves biological processes to reduce organic matter and suspended solids, ensuring compliance with EU effluent standards before discharge. The treated effluent is discharged into the local water system, which ultimately drains into the Somme River and then into the English Channel. The Somme River basin supports diverse aquatic life and is an important ecological corridor in the region. The plant's operation helps protect downstream water quality and the sensitive coastal environment of the English Channel.

The plant discharges into the Somme River basin, which flows into the English Channel. The Somme River and its estuary are ecologically significant, supporting migratory fish species and diverse bird populations. The region's flat topography and agricultural land use mean that nutrient management is important to prevent eutrophication in downstream waters.