Azenit achieves complete control of nitrification and denitrification within a reactor, where sequential aeration operation mode combined with a bacterial selector at the inlet are provided.

As nitrogen, phosphorus, COD, BOD and SS pollutants are removed simultaneously, due to a control of oxygen consumption, Azenit is proposed in a sigle tank configuration.

Azenit can be offered in the following categories

• Azenit : for nitrogen removal.
• Azenit P : for simultaneous nitrogen and phosphorus removal.
• Azenit C+ : with methanol added in a specific tank for low TN requirements or for low COD/N ratios of the influent.
• Azenit BIO+ : for nitrogen load fluctuations (storm flows, seasonal variations e.g. tourism), automatically operates in two configurations : one for low load conditions, the other for high load conditions.
• Azenit C-S : for seasonal industrial influents, highly loaded in carbon, with high bulking risk.

AZENIT is a biological process for waste water treatment and is based around the activated sludge principle.

The AZHNIT'* process is based on experience gained over many years of research, development and operational plants. The process provides the maximum quality and reliability for treatment plants.
AZENIT provides complete control of nitrification and denitrification within a single reactor thanks to the original principle of sequential aeration operation in conjunction with the implementation of a bacterial selector at the inlet to the treatment.

A variant of the process (AZENIT P) enables biological phosphorous removal in addition to carbon and nitrogen based pollution removal. This is achieved by the provision of a strictly anaerobic zone at the inlet of the biological treatment.

AZEN1T can be applied either as a direct treatment of raw water or downstream of a primaiy 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 floe expansion phenomena (bulking). 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.