Cagnes sur mer - 1st positive energy wastewater treatment plant in France

Purification performance - sludge recovery and drying

The Nice Côte d'Azur Metropolis, strongly committed to the ecological transition, inaugurated the new "Aéris" station on 19 November, an innovative and future-oriented facility that is fully in line with the ecological transition objectives of the Metropolis' Territorial Climate Air Energy Plan.

This plant converts its sludge into green energy by injecting biomethane into the GRDF network and valorises the available heat and energy at each stage of its process.

More than a water treatment plant, it is a green site that produces more energy than it consumes. "Aeris" is the first positive energy plant in France!



  • To increase the wastewater treatment performance while guaranteeing it meets European standards 
  • To protect bathing waters and biodiversity 
  • Reduce energy bills through energy savings 
  • Controlling noise and odor pollution during construction and operation
  • Integrate the new plant into its environment (railroad / highway / tourist region) 
  • Develop an educational circuit for the general public


Water treatment:

  • Storage of rainfall surpluses,
    Primary treatment, then rapid flotation Spidflow®.
    New generation biofiltration by Biostyr Duo® 

Sludge line:

  • Sludge treatment with concentration
  • Bioco® low temperature drying
  • Digestion
  • Biogas purification into MemGas® biomethane

Nuisance control:

  • Acoustic insulation of premises
  • Monitoring of deodorization performance by electronic "noses".
  • Creation of two physico-chemical deodorization units completed with activated carbon treatment


A complete and efficient wastewater treatment solution for:  

  • Efficient wastewater treatment
  • High quality discharge into the sea: protection of bathing water and biodiversity
  • Recovery of rainwater to cover irrigation in the site

A complete sludge treatment to:

  • Reduce the volume of sludge on site
  • Reduce truck pollution (CO2) and nuisance to residents/tourists
  • Produce green energy to heat 5500 inhabitants per year
  • Generate a financial income with the resale of biomethane to GRDF (French electricity company)
  • Valorize the dried sludge in the cement plant and participate in the circular economy

Controlling energy consumption

  • Production of 10.5 GWh/year for a consumption of 8.7 GWh/year
  • Production of solar energy with the installation of photovoltaic panels
  • Recovery of unavoidable energy for new uses
  • Choice of low consumption equipment and installation of heat pumps

The consumed and recovered energy will be monitored and an energy management software will be implemented from the first year of operation, in order to gain the ISO 50001 certification.


picto environnement
  • Capacity of the wastewater treatment plant:  160,000 P.E.
  • Production of 10.5 GWh/year for a consumption of 8.7 GWh/year
  • Resale of biomethane to GRDF:  65,000 €/month
  • Production of biomethane equivalent to 5,500 heated households/year
  • Creation of a 2,500 m² area for the preservation of protected species
  • 3,500 hours of professional integration
  • Start-up in 2021