Reducing environmental impact

Replacing a decades-old wastewater treatment plant in the center of a densely populated European metropolis is not a task for the faint of heart. But that is exactly what a Veolia-led consortium did in a northern suburb of France with Lille Métropole’s new Ovilléo wastewater treatment plant that was commissioned in 2014.

In 2010, a six-year design-build-operate contract was awarded by the Lille metropolitan authority to replace an old 1960s wastewater treatment plant. Veolia mobilized all the resources at its disposal to deliver a state-ofthe- art facility to ensure the city complies with key EU directives for decades to come. Serving a population of approximately 620,000 people, the new Ovilléo wastewater treatment plant is not only the largest of its kind in northern France but also features the world’s largest integrated fixed-film activated sludge plant utilizing Veolia’s Hybas™ technology.

The plant, treating both municipal wastewater and stormwater, features a wide range of Veolia’s most advanced treatment technologies. While stormwater will pass through a patented Actiflo® ballasted flocculation system, the wastewater train involves the removal of suspended solids using Multiflo™ lamella settlers, followed by Hybas™ (a combination of activated sludge and AnoxKaldnes’ MBBR technology), before the effluent is polished using proprietary Hydrotech™ Discfilters. The sludge treatment process features Veolia’s continuous thermal hydrolysis technology Exelys™, enabling a significant reduction in the volume of sludge produced, while increasing biogas production. The sludge is then reused by local industry after being dried in a BioCon™ dryer.

The plant’s low carbon footprint and high degree of energy self-sufficiency have significantly reduced the impact on the surrounding environment. Its proximity to residential buildings required particular emphasis to be placed on keeping noise and odors to a minimum, and its compact architectural design freed up land to accommodate a 7-hectare educational garden.