Qta dos Gatos Wastewater Treatment Plant, Samora Correia, Portugal

Qta dos Gatos is a wastewater treatment plant located in Samora Correia, a town in the municipality of Benavente, Santarém District, Portugal. The plant serves a population of approximately 3,500 people and operates under secondary treatment, which is the standard biological treatment required for urban wastewater in Portugal under the EU Urban Waste Water Treatment Directive (91/271/EEC). As a secondary treatment facility, Qta dos Gatos removes organic matter and suspended solids through biological processes, meeting the effluent quality standards set by Portuguese regulations. The plant has a designed capacity of 6,300 m³/day, with an average daily discharge volume of about 584 m³, indicating it operates well below its capacity. This spare capacity allows for future population growth or seasonal variations. The treated wastewater from Qta dos Gatos is discharged into a local watercourse, which eventually drains into the Tagus River estuary and the Atlantic Ocean. The Tagus estuary is a vital ecological area supporting diverse aquatic life and migratory birds. By treating wastewater to secondary standards, the plant helps protect the downstream environment from nutrient pollution and organic loading.

Qta dos Gatos discharges treated effluent into a local tributary that flows into the Tagus River, one of the longest rivers in the Iberian Peninsula. The Tagus River empties into the Atlantic Ocean near Lisbon, forming a large estuary that is ecologically sensitive and supports rich biodiversity, including fish, crustaceans, and migratory waterbirds. Secondary treatment reduces organic pollutants and suspended solids, helping to maintain water quality in the river and estuary, which are important for both ecological health and human uses such as fishing and recreation.