Castelo de Vide A Martinho Wastewater Treatment Plant, Castelo de Vide, Portugal

Castelo de Vide A Martinho is a wastewater treatment plant located in the civil parish of Santiago Maior, Castelo de Vide, in the Portalegre District of Portugal. The plant serves a population of approximately 1,800 residents, making it a small-scale facility within the region's municipal infrastructure. Its location in the Alentejo region, near the Spanish border, places it in a semi-rural setting with agricultural and natural landscapes. The plant provides secondary treatment, which is the standard biological treatment required under the EU Urban Waste Water Treatment Directive (91/271/EEC) for agglomerations with a population equivalent between 2,000 and 10,000. The designed capacity of 3,220 cubic meters per day indicates the facility is sized to handle peak flows, while the actual discharge volume of 300.12 cubic meters per day suggests current loads are well within capacity. The plant operates under Portugal's national water regulations, which implement EU directives and are enforced by the Portuguese Environment Agency (APA). The treated effluent is discharged into the local watershed, which ultimately drains into the Sever River, a tributary of the Tagus River. The Tagus River flows westward through Portugal to the Atlantic Ocean near Lisbon. The plant plays a key role in protecting the water quality of the Sever River, which supports aquatic life and is used for irrigation and recreation in the region.

The plant discharges into the Sever River basin, which flows into the Tagus River, one of the Iberian Peninsula's major rivers. The Tagus River empties into the Atlantic Ocean at the Tagus Estuary, a vital ecosystem for migratory birds and marine life. The region's Mediterranean climate with hot, dry summers and mild, wet winters means that river flows can vary significantly, making consistent wastewater treatment essential to prevent eutrophication and maintain ecological balance in the downstream water bodies.