Azenit™ - A20

Azenit™ can be applied either as a direct treatment of raw water or downstream of a primary settling stage.

The influent passes through a contact zone where the inlet water is mixed with recirculated sludge. This first stage enables selection of non-filamentous species thus avoiding any floc expansion phenomena (bulking).

Total Nitrogen removal

Carbon-based pollution is oxidised and nitrogen eliminated in a biological reactor fitted with a sequential aeration control system (ECOREDOX, REGUL-N).

The bacteria adapt their activity to the organic load and aeration conditions , some carry out nitrification in aerated conditions, others eliminate carbon and carry out denitrification during the non-aeration phases.

The biomass concentration is maintained in the reactor by the partial recirculation of sludges from the clarifier.

Depending upon the characteristics of the waste water to be treated, Azenit™ can be used in two configurations :

  • biological treatment in a single reactor,
  • a single reactor with a dedicated anoxic zone upstream in which the mixed liquors are recirculated.

The nitrification and denitrification stages are optimised by a strict control of the aeration by using the ECOREDOX or REGUL-N systems.

Based on a redox potential measurment, within the biological tank, ECOREDOX and REGUL-N ensure the time repartition between the non aerated and the aerated periods to achieve the requested total nitrogen removal.

Moreover, an additional ammonia concentration monitoring, REGUL-N, downstream to the clarifier provides extra refining for the control of nitrogen treatment.

Furthermore, this optimized control of oxygen demand for the biomass, utilized at numerous Veolia Water Solutions & Technologies' sites, guarantees large energy savings.

Biological Phosphorous Removal :

The biological process is readilly extendable to provide phosphorous removal (Azenit™ P).

This is facilitated by the introduction of a small upstream anoxic zone providing strict anaerobic conditions.

Assimilation of phosphorous by the biomass is optimised at this stage. The anoxic zone replaces the contact zone.

To adapt to particular conditions :

For stringest final water quality or when the influent is carbon-limited, carbon-based substrate is injected downstream of the biological tank.

This post-denitrification stage gives optimum control of nitrates at the outlet with a minimum amount of added reagent (Azenit™ C+ configuration).