MARLE Wastewater Treatment Plant, Marcy-sous-Marle, Hauts-de-France

The MARLE wastewater treatment plant is located in Marcy-sous-Marle, a commune in the Aisne department of Hauts-de-France, France. It serves a population of approximately 3,800 residents, classifying it as a small agglomeration under French and EU regulations. The plant provides advanced treatment, which goes beyond the secondary treatment standard required by the EU Urban Waste Water Treatment Directive (91/271/EEC) for sensitive areas. With a designed capacity of 3,600 m³/day and an actual discharge volume of 677.91 m³/day, the plant operates well below its capacity, indicating room for future growth or seasonal variations. As an advanced treatment facility, it likely incorporates nutrient removal (nitrogen and phosphorus) to protect receiving waters from eutrophication. The plant is operated as part of France's municipal wastewater infrastructure, overseen by regional water agencies. The treated effluent is discharged into local waterways that drain into the Seine River basin, ultimately reaching the English Channel. The advanced treatment level helps safeguard downstream aquatic ecosystems, including the Seine estuary and coastal marine environment. The plant's inland location, over 50 km from the coast, reduces direct marine impact but contributes to the overall water quality of the regional river network.

The plant discharges into the local river system within the Seine River basin, which flows through northern France and empties into the English Channel at Le Havre. The Seine estuary is an ecologically sensitive area supporting diverse aquatic life, including migratory fish species such as salmon and eel. Advanced treatment at this plant helps reduce nutrient loading, protecting downstream water quality and preventing algal blooms in the estuary and coastal zone.