Pego Wastewater Treatment Plant, Abrantes, Portugal

Pego is a wastewater treatment plant located in the Coalhos area of Pego, within the municipality of Abrantes in the Santarém district of central Portugal. The plant serves a population of approximately 2,700 people, placing it in the small agglomeration category under Portuguese and EU regulations. The facility provides advanced treatment, which goes beyond the secondary treatment standard required by the EU Urban Waste Water Treatment Directive (91/271/EEC) for inland plants serving fewer than 10,000 people. With a designed capacity of 3,050 m³/day and an average daily discharge of 450.17 m³/day, the plant operates well below its capacity, indicating room for future growth or seasonal variability. The treated effluent is discharged into the local watershed, which ultimately drains into the Tagus River (Tejo), one of the longest rivers in the Iberian Peninsula. The Tagus flows westward through Portugal and into the Atlantic Ocean near Lisbon. The plant's advanced treatment helps protect the Tagus basin and downstream ecosystems from nutrient pollution and other contaminants.

Pego's treated effluent enters the Tagus River basin, which flows through central Portugal and discharges into the Atlantic Ocean at the Tagus Estuary near Lisbon. The estuary is a vital ecological zone supporting diverse aquatic life, including migratory fish species such as the European eel and various waterbirds. The advanced treatment level at Pego reduces the risk of eutrophication and maintains water quality in this important river system.