Dois Portos Wastewater Treatment Plant, Torres Vedras, Portugal

Dois Portos is a wastewater treatment plant located in the Sirol area of Dois Portos, Torres Vedras, in the Lisbon region of Portugal. It serves a population of approximately 5,400 people, classifying it as a small to medium agglomeration under Portuguese and EU regulations. The plant is situated inland, more than 10 km from the coast, and its treated effluent is discharged into the local watershed. The plant operates with secondary treatment, which is the standard required by the EU Urban Waste Water Treatment Directive (91/271/EEC) for agglomerations of this size. The designed capacity is 6,900 m³/day, and the current discharge volume is 900.35 m³/day, indicating operational headroom. As a Portuguese facility, it is subject to national water quality standards and EU directives, ensuring proper treatment before discharge. The treated wastewater from Dois Portos ultimately drains into the Atlantic Ocean via the Tagus River basin or nearby coastal streams. The region's water bodies support diverse aquatic life and are important for local agriculture and recreation. Proper treatment helps protect these ecosystems from nutrient pollution and pathogens.

The plant discharges into the local watershed, which is part of the Tagus River basin, eventually reaching the Atlantic Ocean. The receiving waters support diverse aquatic ecosystems and are used for irrigation and recreation. Effective secondary treatment reduces organic load and suspended solids, protecting downstream water quality and marine habitats.