Pontes de Monfalim Wastewater Treatment Plant, Sobral de Monte Agraço, Portugal

Pontes de Monfalim is a wastewater treatment plant located in Quinta de Monfalim, Santo Quintino, Sobral de Monte Agraço, in the Lisbon district of Portugal. The plant serves a population of approximately 3,000 people, classifying it as a small agglomeration under Portuguese and EU regulations. The plant provides secondary treatment, which is the minimum standard required by the EU Urban Waste Water Treatment Directive (91/271/EEC) for discharges into freshwater and estuaries. With a designed capacity of 4,433 m³/day and an average discharge volume of 500.19 m³/day, the plant operates well below its capacity, indicating room for future growth or seasonal variability. The treated effluent is discharged into local watercourses that ultimately drain into the Tagus River basin and the Atlantic Ocean. The plant plays a key role in protecting the region's water quality, supporting both local ecosystems and downstream communities that rely on these water bodies.

The plant discharges into the Tagus River basin, which flows into the Atlantic Ocean near Lisbon. The Tagus estuary is an ecologically sensitive area that supports diverse aquatic life, including migratory fish and bird species. The secondary treatment provided by the plant helps reduce organic pollutants and suspended solids, mitigating eutrophication risks in the downstream environment.