Gaviao Wastewater Treatment Plant, Gavião, Portugal

The Gaviao wastewater treatment plant is located in the municipality of Gavião, Portalegre district, Portugal. It serves a population of approximately 2,600 people, placing it in the small agglomeration category under the EU Urban Waste Water Treatment Directive (UWWTD). The plant is situated inland, away from coastal areas, and treats wastewater from the local community. The plant employs advanced treatment processes, which go beyond the secondary treatment standard required by the EU UWWTD 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 2,638 cubic meters per day and currently discharges an average of 433.50 cubic meters daily, indicating significant spare capacity. The treated effluent is discharged into a local watercourse, likely a tributary of the Tagus River basin, which flows westward through Portugal to the Atlantic Ocean near Lisbon. The plant's advanced treatment helps safeguard water quality in the Tagus basin, supporting aquatic ecosystems and downstream water uses.

The Gaviao plant discharges into a small watercourse within the Tagus River basin, one of the Iberian Peninsula's major river systems. The Tagus flows through central Portugal and Spain, eventually reaching the Atlantic Ocean at Lisbon. The basin supports diverse aquatic life and is an important resource for irrigation and drinking water. Advanced treatment at the plant reduces nutrient loads, helping to prevent eutrophication in downstream reservoirs and the Tagus estuary.