Nitrogen and/or phosphorus removal

Azenit™ is an optimized wastewater treatment process by activated sludge for nitrogen and/or phosphorus removal.



Azenit™ removes simultaneous nitrogen, phosphorus, COD, BOD and suspended solids, including a bacterial tank and oxygen consumption control.

Azenit™ can be included in the effluent treatment chain, directly on pretreatment downstream or after a primary treatment.


Main Configurations

  • Azenit™: for nitrogen removal.
  • Azenit™ P: for simultaneous nitrogen and phosphorus removal.
  • Azenit™ C+: with methanol added for an efficient output for low global residual nitrogen requirements or for low COD/N ratios of the influent.
  • Azenit™ BIO+: for nitrogen load fluctuations (stormwater, seasonal variations e.g. tourism), the running of the reactor switches automatically between two configurations: one for low load conditions, the other for high load ones.
  • Azenit™ C-S: for seasonal industrial influents, highly loaded in carbon, with high bulking risk.



Some References

  • Mantes, France, 2012, Azenit™ for a daily average flow of 1,800 m³/d
  • Lillebonne, France, 2011, Azenit™ for a daily average flow of 300 m³/d
  • Brussels North, Belgium, 2007, Azenit™ P for a daily average flow of 558,000 m3/d
  • Rouen / Emeraude, France, 1997, Azenit™ P for a daily average flow of 85,000 m3/d
  • Lourdes, France, 2004, Azenit™ for a daily average flow of 25,000 m3/d


The influent passes through a contact zone where the inlet water is mixed with a part of recirculated sludge. This first stage of Azenit™ process enables selection of non-filamentous bacteria thus avoiding any floc bulking.


Total Nitrogen Removal

Carbon pollution is oxidized and nitrogenous pollution is eliminated in a biological reactor fitted with a sequential aeration control system (ECOREDOX).

The purifying biomass makes the nitrogen nitrification in aerated zone and the denitrification in anoxic zone.

Thanks to the contact zone, it can handle load variations without a system disturbance.
The biomass concentration is maintained and controlled in the reactor by acting on the recirculation or extraction of sludge from the clarifier.

Depending on the characteristics of the wastewater to be treated, Azenit™ can be used in two configurations:

  • Biological treatment in a reactor, oxidation channel type
  • Separated anoxic and aerobic zones configuration with recirculation of mixed liquor.


The nitrification and denitrification stages are optimised by a strict control of the aeration by using the ECOREDOX process.


Resources & Product range