Melgaco Wastewater Treatment Plant - Melgaço, Portugal

The Melgaco wastewater treatment plant is located in Galvão, Melgaço, in the Viana do Castelo district of northern Portugal. It serves a population of approximately 2,900 people, making it a small-scale municipal facility. The plant is situated inland, more than 10 km from the coast, but within 50 km of the Atlantic Ocean. 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 of this size. Secondary treatment typically involves biological oxidation and sedimentation to remove organic matter and suspended solids. The plant has a designed capacity of 3,161 m³/day and currently treats an average daily flow of 483.52 m³/day, indicating ample capacity for current loads. The treated effluent is discharged into the local watershed, which drains into the Minho River or its tributaries. The Minho River forms the border between Portugal and Spain and flows into the Atlantic Ocean near Caminha. This coastal area supports diverse aquatic life and is an important ecological zone for migratory fish species such as salmon and lamprey.

The plant discharges into the Minho River basin, which flows into the Atlantic Ocean. The Minho estuary is a productive ecosystem supporting diverse aquatic life, including migratory fish and bird species. The surrounding region is characterized by agricultural and forested landscapes, with the river providing water for irrigation and recreation. The plant's secondary treatment helps protect water quality in this sensitive coastal environment.