The Greater Paris Sanitation Authority (SIAAP) and environmental services firm SUEZ have officially inaugurated a major biogas production unit at the Seine Aval wastewater treatment plant, marking a significant step in France’s transition to renewable energy, reports Bioenergy Insight.
Located in the Paris metropolitan area, the Seine Aval plant is the largest wastewater treatment facility in Europe, serving over six million residents across seven municipalities including Achères, Conflans-Sainte-Honorine, and Saint-Germain-en-Laye.
The new biogas facility, led by a consortium headed by SUEZ, is now the largest of its kind in France. It plays a central role in SIAAP’s long-term site modernisation programme, which has been underway since 2009.
“This new biogas unit is a milestone in our plan to modernise the Seine Aval site,” said François-Marie Didier, Chairman of SIAAP. “It allows us to transform 130,000 tonnes of sewage sludge each year into renewable energy and fertiliser, while improving safety, efficiency, and our environmental impact.”
SUEZ CEO Xavier Girre highlighted the collaborative nature of the project. “This achievement shows what can be done when expertise and partnerships come together. The new unit improves the plant’s environmental footprint and performance while showcasing our leadership in sludge recovery.”
Construction of the biogas unit began in 2016 and was carried out by a consortium that included SUEZ, Chantiers Modernes Construction (a subsidiary of Vinci), Demathieu Bard Construction, SOGEA Environnement, and the architecture firm Thetis Tanguy du Bouetiez.
With a treatment capacity of 130,000 tonnes of sludge annually, the facility now produces 350 GWh of renewable energy, enough to meet 56% of the plant’s total energy needs — making the site fully self-sufficient.
Equipped with compact design features, advanced deodorisation systems, and flexible sludge processing capabilities, the facility is built to handle varying waste conditions safely and efficiently.
The total project investment reached €401 million (excluding VAT), of which €373 million was allocated to the construction consortium. It received €32 million in grants and €16 million in interest-free loans from the Seine Normandy Water Agency.
The new unit reflects both SIAAP’s and SUEZ’s commitment to sustainable infrastructure and the growing role of wastewater facilities in supporting the clean energy transition.
