Lagares Wastewater Treatment Plant
The modernization and expansion of the Lagares Wastewater Treatment Plant (WWTP) in Vigo, Spain, represents one of the most significant wastewater and environmental engineering projects undertaken in the country. The facility was developed to meet the requirements established by Directive 91/271/EEC for sensitive areas with populations exceeding 100,000 inhabitants, providing the metropolitan area with infrastructure capable of handling flows of up to 12 m³ per second. The new plant has quadrupled the hydraulic capacity of the former facility and can treat wastewater equivalent to that generated by 800,000 inhabitants, significantly enhancing the protection of the Vigo estuary and surrounding coastal environment.
Entirely designed by the engineering teams of OHLA and GS Inima, the Lagares WWTP stands out for incorporating innovative solutions that position it among the most advanced facilities in Europe. A key feature is its thermal hydrolysis system for sludge treatment, a pioneering technology that increases anaerobic digestion efficiency and maximizes biogas production for renewable energy generation. In addition, the facility is the largest wastewater treatment plant in Spain using biological treatment through biofiltration technology and one of the largest of its kind in Europe.
From both a technical and environmental perspective, the plant incorporates advanced impact mitigation and control systems. Odour treatment is carried out through a Biotrickling biological deodorization system, which effectively minimizes nuisance emissions. Furthermore, the entire facility is enclosed within a large covered structure that reduces both noise and odour impacts while promoting seamless integration into the surrounding urban environment. Since entering operation, the plant has significantly improved the microbiological quality of local bathing waters, contributing to the recovery of the Blue Flag certification for Samil Beach and establishing itself as a benchmark project within the wastewater and environmental engineering sector.
The technical, environmental and architectural excellence of the Lagares WWTP has been widely recognized at both national and international levels. Among its most prestigious distinctions is the Segovia Aqueduct Award for Public Works and the Environment, presented by the Fundación Caminos and the Spanish Institution of Civil Engineers. This accolade adds to the Best Engineering Project Award at the 2019 San Telmo Awards, granted by the Galician Association of Civil Engineers in recognition of the project’s innovative character.
The facility has also received the 2018 Galicia Architecture and Rehabilitation Award, granted by the Regional Government of Galicia; the 2017 Gran de Área Award, presented by the Official Association of Architects of Galicia; and the prestigious international WEX Global 2016 Water & Energy Award. More recently, in 2021, the Spanish National Construction Confederation recognized the Lagares WWTP as one of the infrastructure projects that has most significantly improved quality of life in Spain, highlighting its scale, technological innovation and contribution to environmental sustainability.