Ecological Wastewater Treatment Plant, Briis-sous-Forges

Project overview:
“In producing the portrait of the Earth from above, I realised, in an even more striking way, that water and life are bound together. Water is one of the great cycles we need in order to live — we and everything that lives around us. It is therefore important that humans take their place within this cycle while disturbing it as little as possible.” — Yann Arthus-Bertrand.

The Briis-sous-Forges wastewater treatment plant lives up to that aspiration: that of sustainable development. It is also a place open to visitors, and an example that will inspire other individual and collective initiatives — because each of us has a role to play, each of us has the power and the duty to act and to get involved.

A NATURALLY AMBITIOUS PROJECT WITH MULTIPLE CHALLENGES
The SIAL plant (the Inter-municipal Sanitation Authority of the towns of Pecqueuse, Limours, Briis-sous-Forges and Forges-les-Bains) no longer met the standards of the European Water Framework Directive nor the demands of the local population density. The plant is rebuilt on the same site as the previous one, alongside agricultural land and the Prédecelle river. Aware of the challenges relating to water, the local authority set new environmental protection objectives. In 2007, it therefore naturally chose the most committed and pioneering professionals in the field of eco-performance to deliver this ambitious project.

A NEW-GENERATION WASTEWATER TREATMENT PLANT
Designed and built by Stereau and COSTE Architectures, this treatment plant is structured around three treatment units:
1. An innovative wastewater treatment using a flat-sheet Aqua-RM® membrane bioreactor, delivering remarkable effluent quality in terms of physico-chemical and even bacteriological parameters. Compact and high-performing, this technology exceeds the required performance. As a result, the quality of the Prédecelle river has been significantly improved, thanks to the complete removal of suspended matter, advanced treatment of carbon (COD), nitrogen and phosphorus, and the thorough elimination of bacteria, viruses and parasites. The Briis-sous-Forges plant is upgradeable: micropollutant treatment can be added through the Carboplus® process (adsorption on powdered activated carbon) without any other change to the treatment line.
2. Sludge and air treatment using Jardins Filtrants® (Filtering Gardens), a natural alternative for sludge treatment using plants. This eco-friendly process, requiring no chemical reagents, ensures sludge stabilisation and dewatering through the action of the rhizosphere. The 30% dryness achieved makes it possible to reuse the sludge as humus for agricultural purposes. The plant's performance requirements make Aqua-RM® combined with Jardins Filtrants® the most appropriate processes in terms of investment and operating costs.
3. The biodiversity trail. The visit begins at the meeting point of water and earth, between the building and the Jardins Filtrants®. It is marked by a shelter linking the gardens and the building. The trail explains the journey of water throughout its treatment, all the way to the receiving environment, through the gardens. Visitors are made aware of the importance of water quality and its impact on biodiversity. Pathways allow visitors to walk through the sludge and air filtering gardens to observe the treatment process and the recreation of ecological habitats (refuges for fish, frogs, dragonflies, etc.). With a capacity of 20,000 population-equivalents, this facility — operated by Lyonnaise des Eaux since 2009 — treats the effluents of the towns of Pecqueuse, Limours, Briis-sous-Forges and Forges-les-Bains.

TECHNICAL CHARACTERISTICS OF THE PLANT
Treatment capacity: 20,000 PE — Average daily flow: 4,208 m³/day