Lagares Wastewater Treatment Plant Modernization and Expansion

OHLA served the Municipal Utility Authority in Vigo, Spain, as prime contractor to perform an extensive modernization and expansion project at the Lagares Wastewater Treatment Plant, which services the City of Vigo and surrounding communities. The treatment system is designed to process pollution loads equivalent to approximately 800,000 population equivalents, establishing the facility as one of the largest and most advanced wastewater treatment plants in Spain and among the largest in Europe.

For the project, the team used biofiltration technology, making Lagares the largest biological wastewater treatment plant in Spain utilizing this approach.  Also implemented was the use of thermal hydrolysis for sludge treatment, improving anaerobic digestion efficiency and significantly increasing biogas energy recovery.  Biological odor control (bio-trickling) systems for treatment of odorous process air and extensive structural enclosure to control noise and odor impacts and facilitate integration into the surrounding urban environment were integrated into the design. To ensure delivery of a fully functional, modern plant, comprehensive hydraulic and process upgrades to improve overall effluent quality and system reliability were incorporated into the design.

The upgraded facility was designed to comply with Directive 91/271/EEC governing wastewater discharges for sensitive receiving waters serving populations greater than 100,000 inhabitants.

The completed project provides a maximum hydraulic capacity of approximately 274 million gallons per day, representing a fourfold increase in capacity over the original plant.

The award-winning project, which was designed and engineered by OHLA and GS Inima technical teams, encompassed conceptual design, detailed engineering, process selection, and integration of advanced treatment technologies. The project was recognized with multiple awards, including the Acueducto de Segovia Public Works and Environment Award, San Telmo Award for Best Engineering Work, Galicia Architecture and Rehabilitation Award, WEX Global Water & Energy Award, and the National Construction Confederation Recognition for projects improving quality of life.