Coja Wastewater Treatment Plant: Serving Côja e Barril de Alva, Portugal

Coja wastewater treatment plant is located in Côja e Barril de Alva, a parish in the municipality of Arganil, Coimbra District, Portugal. The plant serves a population of approximately 2,500 people, reflecting its role as a small-scale municipal facility in a rural inland setting. The plant provides secondary treatment, a standard biological process that removes organic matter and suspended solids. With a designed capacity of 2,700 m³/day and an average discharge volume of 416.83 m³/day, the facility operates well within its capacity. Under the EU Urban Waste Water Treatment Directive (91/271/EEC), agglomerations of this size are required to have appropriate collection and treatment systems, and secondary treatment is the minimum standard for freshwater discharges. The treated effluent is discharged into the local watershed, which ultimately drains into the Alva River, a tributary of the Mondego River. The Mondego River flows through central Portugal and reaches the Atlantic Ocean near Figueira da Foz. The plant's operation helps protect the water quality of these rivers and the downstream coastal environment.

The plant discharges into the Alva River basin, a tributary of the Mondego River, which flows into the Atlantic Ocean. The Mondego River supports diverse aquatic life and is an important water resource for agriculture and urban areas in central Portugal. The secondary treatment provided by the plant reduces organic pollution and protects the ecological health of the river system.