Alizair™ is a biological deodorization process using biofiltration.
It operates by bio-oxidation of compounds in the liquid phase.
As they pass through the filter, the malodorous molecules are biodegraded by specific micro-organisms on the support media.
The Alizair™ media rests on a perforated floor which participates in the uniform distribution of the polluted air in the structure. The air to be treated rises through it.
Regular watering maintains stable humidity in the filter, nutrients required for biological activity are injected and products from biological oxidation are removed (including sulfates).
The water recovered at the bottom of the reactor is recirculated or removed at the plant head.
The choice of filter media
Depending on the elements present in the air to be treated, the bio-deodorization operates with different types of micro-organisms, which imply different operating conditions.
Through its experience of biological processes, Veolia has been able to develop various packing media to optimize the process performance.
The best performances for hydrogen sulfide, other sulfides, ammonia and amine (RNH₂) removal are achieved by using autotrophic species.
In this case, the material used is Biodagene™, a non-degradable mineral. This is a granular material with high porosity.
A solution of nutritive elements is sprayed on the filter media to feed the purifying biomass. Generally, at least the following elements are required to ensure optimal operation:
- A source of Carbon
- A source of Nitrogen and Phosphorus
Usually, the watering with raw water on the filter media is enough to maintain the necessary nutrient and humidity levels.
The watering sequences of the filter bed are handled automatically depending on the air flow rate to treat. Sprinkling intensity also depends on the particle size of the present material.
Alizair™ A can achieve very high filtration rates (500 m³/m²/h) with treatment loads which can exceed 50g/h/m³ of medial.
When Volatile Organic Compounds (VOC) treatment is required, the filter and its operation are set up in order to enhance the development of heterotrophic species.
The granular medium used is made from peat. This variant of the process is called Alizair™ H.