Pegoes Wastewater Treatment Plant - Montijo, Portugal

Pegoes is a wastewater treatment plant located in Pegões, Montijo, in the Setúbal district of Portugal. It serves a population of approximately 2,700 people, classifying it as a small agglomeration under EU standards. The plant is situated inland, more than 10 km from the coast, and operates within the Tagus River basin. The plant provides secondary treatment, which is the minimum required by the EU Urban Waste Water Treatment Directive (91/271/EEC) for freshwater discharges from agglomerations of this size. Its designed capacity is 5,100 m³/day, with an average daily discharge of 450.17 m³/day, indicating significant spare capacity. As a Portuguese facility, it is regulated by the national water authority (APA - Agência Portuguesa do Ambiente) under EU directives. The treated effluent is discharged into local watercourses that eventually drain into the Tagus River estuary, a major ecological and economic resource. The estuary supports diverse aquatic life and is an important migratory corridor for birds. The plant's operation helps protect downstream water quality in the Tagus and the adjacent Atlantic coastal zone.

The plant discharges into the Tagus River basin, which flows into the Tagus estuary near Lisbon. This estuary is one of Europe's largest wetlands, supporting rich biodiversity including fish, crustaceans, and migratory birds. The plant's secondary treatment reduces organic load and suspended solids, helping to maintain the ecological balance of the estuary and downstream coastal waters.