Crestuma Wastewater Treatment Plant, Vila Nova de Gaia, Portugal

Crestuma is a municipal wastewater treatment plant located in Vila Nova de Gaia, Porto District, Portugal. It serves a population of approximately 3,200 residents, classifying it as a small agglomeration under EU regulations. The plant is situated in the Crestuma area, near the Douro River, and is part of the region's wastewater infrastructure. The plant provides secondary treatment, which is the minimum required by the EU Urban Waste Water Treatment Directive (91/271/EEC) for freshwater discharges from agglomerations of this size. With a designed capacity of 5,000 m³/day and an average discharge volume of 533.54 m³/day, the plant operates well below its capacity, indicating room for future growth or seasonal variations. Treated effluent from Crestuma is discharged into the Douro River, which flows westward through Porto and into the Atlantic Ocean. The Douro River basin supports diverse aquatic life and is an important ecological corridor in northern Portugal. The plant's secondary treatment helps protect water quality in the river and downstream coastal areas.

Crestuma discharges treated wastewater into the Douro River, which flows approximately 100 km west to the Atlantic Ocean near Porto. The Douro River basin is a major hydrological feature in the Iberian Peninsula, supporting diverse freshwater ecosystems and providing water for agriculture and urban use. The plant's secondary treatment reduces organic pollutants and suspended solids, helping to maintain water quality in the river and its estuary, which is an important habitat for migratory fish and bird species.