Arcos de Valdevez Wastewater Treatment Plant - Serving 9,200 People in Viana do Castelo, Portugal

The Arcos de Valdevez wastewater treatment plant is located in the town of Arcos de Valdevez, within the Viana do Castelo district of northern Portugal. The facility serves a population of approximately 9,200 residents, classifying it as a medium-sized agglomeration under European Union regulations. As a Portuguese plant, it operates under the EU Urban Waste Water Treatment Directive (91/271/EEC), which requires secondary treatment for agglomerations between 2,000 and 10,000 population equivalent discharging into freshwater. The plant's designed capacity is 1.00 (likely in thousands of cubic meters per day or similar units), supporting its service population. The treated effluent is discharged into the local watershed, which ultimately drains into the Atlantic Ocean via the Lima River basin. The plant plays a key role in protecting the Vez River, a tributary of the Lima, and the downstream estuarine and coastal ecosystems from nutrient pollution and pathogens.

The plant discharges into the Vez River, a tributary of the Lima River, which flows into the Atlantic Ocean at Viana do Castelo. The Lima estuary supports diverse aquatic life and is an important migratory corridor for fish species. The plant's treatment helps reduce nutrient loading and protect the ecological health of this coastal watershed.