Aldeia Gavinha Wastewater Treatment Plant, Alenquer, Portugal

Aldeia Gavinha wastewater treatment plant is located in the parish of Aldeia Gavinha, within the municipality of Alenquer, in the Lisbon district of Portugal. The plant served a population of approximately 1,700 people and was designed with a capacity of 2,300 cubic meters per day. It is now closed and no longer operational. The plant provided secondary treatment, which is the standard biological treatment required under the EU Urban Waste Water Treatment Directive (91/271/EEC) for agglomerations of this size. The directive mandates secondary treatment for populations between 2,000 and 10,000 in inland areas, and Aldeia Gavinha falls below that threshold, indicating that the plant met or exceeded regulatory expectations for its scale. The treated effluent from the plant was discharged into a local watercourse that ultimately drains into the Tagus River basin, one of the most important river systems in the Iberian Peninsula. The Tagus River flows westward through Portugal and empties into the Atlantic Ocean near Lisbon. The plant's operation contributed to protecting the local aquatic environment and downstream water quality.

The plant discharged into a tributary of the Tagus River, which flows through central Portugal and into the Atlantic Ocean at the Tagus Estuary near Lisbon. The estuary is an ecologically important area supporting diverse aquatic life, including migratory fish species. The plant's secondary treatment helped reduce organic pollution and protect the downstream ecosystem, though its closure may shift treatment demands to neighboring facilities.