Chamusca Wastewater Treatment Plant | Santarém, Portugal

The Chamusca wastewater treatment plant is located in the town of Chamusca, in the Santarém district of central Portugal. The facility serves a population of approximately 3,700, making it a small agglomeration under Portuguese and EU classifications. The plant is situated inland, away from coastal areas, and treats domestic wastewater from the local community. The plant operates with advanced treatment, which goes beyond the secondary treatment required by the EU Urban Waste Water Treatment Directive (91/271/EEC) for agglomerations of this size. Advanced treatment typically includes nutrient removal (nitrogen and phosphorus) to protect sensitive receiving waters. The plant has a designed capacity of 3,700 m³/day and currently treats a daily volume of 616.90 m³, indicating significant spare capacity. The treated effluent is discharged into a local watercourse that eventually drains into the Tagus River basin, one of the major river systems in the Iberian Peninsula. The Tagus River flows westward through Portugal and discharges into the Atlantic Ocean near Lisbon. The advanced treatment helps protect the ecological health of the Tagus River and its downstream estuary, which supports diverse aquatic life and is an important migratory corridor for fish species.

The plant discharges into a tributary of the Tagus River basin, which flows through central Portugal and into the Tagus Estuary near Lisbon. The estuary is a vital ecosystem for migratory birds and fish, including species such as the European eel and lamprey. Advanced treatment at this plant reduces nutrient loads, helping to prevent eutrophication in the river and estuary.