Arraiolos Poente Wastewater Treatment Plant, Arraiolos, Portugal

Arraiolos Poente is a wastewater treatment plant located on EN 4 in Arraiolos, a town in the Évora district of Portugal. The plant serves a population of 2,600 and operates with secondary treatment, which is the standard level required under the EU Urban Waste Water Treatment Directive for agglomerations of this size. The plant has a designed capacity of 3,000 m³/day and currently discharges an average volume of 433.5 m³/day, indicating it operates well below its capacity. As a secondary treatment facility, it removes organic matter and suspended solids, meeting the effluent quality standards set by Portuguese regulations and the EU directive. The treated effluent is discharged into the local watershed, which ultimately drains into the Sado River basin and then into the Atlantic Ocean near Setúbal. The plant plays a key role in protecting the region's water resources, supporting both agricultural activities and the ecological health of the Sado estuary, a vital habitat for aquatic life.

The plant discharges into the Sado River basin, which flows into the Sado estuary and then the Atlantic Ocean. The Sado 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 nutrient and organic pollution, protecting downstream water quality and the estuary's ecological balance.