Vila Franca de Xira Wastewater Treatment Plant - Tagus Estuary, Portugal

The Vila Franca de Xira wastewater treatment plant is a municipal facility located in Vila Franca de Xira, a town in the Lisbon District of Portugal. It serves a population of approximately 47,100 residents, placing it in the medium agglomeration category under Portuguese and EU regulations. The plant is situated on the banks of the Tagus River, near the river's estuary, and is within 50 km of the Atlantic coast. As a plant serving a population equivalent of 47,100, it falls under the EU Urban Waste Water Treatment Directive 91/271/EEC, which requires secondary treatment for discharges into freshwater and estuaries. The plant is expected to meet the directive's standards for biological treatment and nutrient removal, particularly given the sensitivity of the Tagus estuary ecosystem. The designed capacity is 1.00 (likely in thousands of cubic meters per day), indicating a facility sized for its service population. The treated effluent is discharged into the Tagus River, which flows into the Tagus estuary and then into the Atlantic Ocean near Lisbon. The estuary is a vital ecological zone supporting diverse aquatic life, including migratory fish species and waterbirds. The plant's operations are crucial for protecting water quality in this ecologically sensitive area, which is also important for local fisheries and recreation.

The plant discharges into the Tagus River, which flows into the Tagus estuary, one of Europe's largest estuaries, before reaching the Atlantic Ocean. The estuary supports a rich ecosystem, including important fish nurseries and migratory bird populations. The plant's location near the coast and within the estuary's watershed means its effluent quality directly affects the health of these downstream environments, making proper treatment essential for maintaining ecological balance.