MERIDA Wastewater Treatment Plant, Mérida, Extremadura, Spain

The MERIDA wastewater treatment plant is located in the Polígono Industrial El Prado district of Mérida, in the Extremadura region of Spain. Serving approximately 85,000 people, the plant is a key component of the city's municipal wastewater infrastructure, handling domestic and industrial flows from this historic urban center. As a Spanish facility, the plant operates under the EU Urban Waste Water Treatment Directive (91/271/EEC), which mandates secondary treatment for agglomerations with a population equivalent (PE) between 10,000 and 150,000. For a population of 85,000, the directive requires at least secondary biological treatment, with potential tertiary treatment if the receiving waters are designated as sensitive areas. The plant's design and operational practices align with these regulatory standards to protect water quality. The treated effluent is discharged into the Guadiana River basin, which flows through Extremadura and eventually reaches the Gulf of Cádiz in the Atlantic Ocean. The Guadiana River supports diverse aquatic ecosystems and is an important water resource for agriculture and biodiversity in the region. The plant's operation helps maintain the ecological health of this river system by reducing pollutant loads.

The MERIDA plant discharges into the Guadiana River, a major Iberian watercourse that flows southwest through Spain and Portugal before emptying into the Gulf of Cádiz. The Guadiana basin supports a variety of habitats, including riparian forests and wetlands, which are home to species such as the Iberian lynx and the Spanish imperial eagle. The plant's treatment processes help mitigate nutrient and organic pollution, preserving water quality for downstream communities and sensitive ecosystems in the estuary.