France's first energy-positive wastewater treatment plant

As of 2019, the Cagnes-sur-Mer station will treat the wastewater of 160,000 inhabitants of the Symisca, a syndicate grouping together the Nice Côte d'Azur metropolis and the municipalities of Cagnes-sur-Mer, La Colle-sur-Loup, Villeneuve Loubet and St-Paul-de-Vence.
Located on industrial wasteland between the railroad and the highway, this plant will be France's first positive-energy wastewater treatment plant.


Innovative and high-performance equipment

In order to increase purification performance and guarantee water treatment in compliance with European standards, the consortium of companies (OTV representative) proposed a range of complementary, modular and efficient processes:

  • storage of surplus rainfall
  • a primary treatment, followed by rapid flotation using Spidflow®
  • new generation " Biostyr Duo® " biofilters, ergonomic and self-contained,
  • sludge treatment with concentration then drying at low temperature before digestion

Effective and controlled energy savings

In order to ensure that the station produces more energy than it consumes, in all seasons, several sources are guaranteed:

  • lower consumption thanks to good insulation, a reduction in the volume of sludge produced and the reuse of treated water,
  • the sludge generated is recovered as a "product", making it possible to compensate at a minimum for the energy consumption used in its treatment,
  • exemplary energy approach with limited consumption, recovery of all potential sources (solar, heat pumps, etc.), and production of biomethane for resale by reinjection into the GrdF network.

In order to qualify for the ISO 50001 standard, a follow-up of the consumed and recovered energies will be monitored and an energy management software will be set up as from the 1st year of operation.

Controlled nuisances

Respectful of its neighbours, the Symisca guarantees perfect control of noise and odour nuisance, both during construction work and afterwards during operation, thanks to :

  • the acoustic insulation of the premises
  • vehicle passage control
  • the creation of two physico-chemical deodorization units supplemented by activated carbon treatment
  • monitoring the performance of deodorization through electronic "noses".

A pleasant and humane architecture

The new plant will be located between the Domaine du Loup and the racecourse, on the outskirts of Cagnes-sur-Mer. The design of the building will take into account all the particularities of the site:  an industrial building treated as a residential structure and surrounded by green spaces.
An educational tour of the plant will be available for up to 50 visitors. As for the former wastewater treatment plant, locals will discover that it has been transformed into an urban park, located on the banks of the river Cagne, with the storm basin covered with vegetation.