Valdeao Wastewater Treatment Plant, Almada, Portugal - Secondary Treatment, Coastal Discharge

Valdeao is a wastewater treatment plant located in Almada, Setúbal, Portugal. It serves a population of approximately 3,000 people, classifying it as a small agglomeration under Portuguese and EU regulations. The plant is situated in the urban area of Pragal, within the municipality of Almada, near the Tagus River estuary. The plant provides secondary treatment, which is the standard required by the EU Urban Waste Water Treatment Directive (91/271/EEC) for discharges into sensitive areas and for agglomerations of this size. The designed capacity is 6,000 m³/day, with an actual discharge volume of 500.19 m³/day, indicating ample reserve capacity. As a coastal plant within 10 km of the Atlantic Ocean, it must meet stringent effluent quality standards to protect marine waters. The treated effluent likely discharges into the Tagus River estuary, which flows into the Atlantic Ocean near Lisbon. The estuary is a vital ecosystem supporting diverse aquatic life and migratory birds. The plant's operation helps reduce nutrient and pollutant loads, contributing to the health of the estuary and coastal waters.

Valdeao plant discharges into the Tagus River estuary, one of Europe's largest estuaries, which flows into the Atlantic Ocean. The estuary supports rich biodiversity, including fish nurseries and migratory bird populations. As a coastal facility, the plant's secondary treatment helps mitigate eutrophication risks in the sensitive marine environment.