Biofiltration

 

Odour abatement via natural biodegradation processes !

 

 

Content

1. Process Description

2. The LANODOR® Process (Stereau, F)

3. Applications

4. Advantages inorganic vs organic biobed

5. Dimensioning

6. References

 

1. Process Description 

 
Biofiltration consists in degrading organic and inorganic (H2S, NH4) molecules with specific micro-organisms growing on carriers. Those carriers are particulate or fibrous, organic or inorganic materials that are filled in a container, so forming  the biobed.

 

A major problem with most of organic carriers is that they decompose with time. The biobed starts shrinking, creating emission channelling through the biobed and along its sides and consequently reducing the abatement efficiency. Since those carriers are quite large, the biofilter volume is usually big and the requested surface is huge.

 

Micro-organisms need a water film around their membrane to stay alive and to absorb the emission contaminants. An organic biobed cannot be sprayed with water, what accelerates its decomposition. Consequently, the emission, if not saturated, must be pre-washed.

 

Inorganic carriers of regular shape and size, thanks to their smaller size and stronger structure, build compacter biobeds that cannot shrink. They can be sprayed with water, that also helps to remove excess biomass and reaction products, like sulphuric acid,…

 

Nitrobacter and Thiobacillus bacteria degrade H2S and NH3 respectively. They are both Autotrophic bacteria, synthesising their molecules from inorganic compounds and from CO2 and carbonates, as carbon source. For their optimal activity, they require high and low pH respectively.

 

Heterotrophic bacteria, synthesising their molecules from inorganic and organic compounds, degrade organic molecules, like mercaptans and amines, and work optimally at neutral pH. If one bacteria family is dominating, it usually inhibits the growth of the other families.

 

2. The LANODOR® Process (Stereau, F)  

 
 
 
 
The LANODOR® Process uses highly porous and abrasion resistant lava stones, or pozzolana, of regular shape & size (3-5mm), called Biozzolane®”.
 
 
 
 
A marble layer, covering the Biozzolane, releases caustic when the bed is sprayed with water, creating a pH gradient in the biobed and consequently an optimal micro-organism repartition and growth.
 

The micro-organisms can find the essential minerals for their growth in the lava stone. If necessary, a bit of nitrogen & phosphor containing compounds can be added in the water for guaranteeing an optimal bacteria growth.

 

The LANODOR® Process alleviates all the problems encountered with an organic biofilter and its pH gradient makes it unique among the existing inorganic biofilters.

 

If the abatement has to be improved, an oxydo-basic washer or an activated carbon filter can be added on its downstream side.

 

3. Applications 

 
This technology is ideal for treating odorous emissions released  from substrates at ambient T°, like waste water, compost processes,… mainly containing soluble & good biodegradable molecules like H2S, NH3,  mercaptans,..

 

4. Advantages inorganic vs organic biobed 

  •   Lower lifetime: > 10 years vs 2-3 years
  •   Lower pressure drop: 300Pa vs 800Pa
  •   Higher gas velocity: 0.1-0.2 m/s vs 0.01-0.02 m/s
  •   Smaller bed size: factor 5
  •   No bed shrinking and clogging with biomass => no channelling and pressure drop increase
  •   H2S abatement: 50g/m3.h vs 10g/m3.h

5. Dimensioning 

  • Gas velocity: V=500m/s;
  • Bed Surface = Flow / V;
  • Bed Height = 10cm large pozzolane + 70cm Biozzolane® + 30cm marble

6. References 

 
France: Waste water plants at Borme les Mimosas, Les Sables d’Olonnes, Detwiller, Riom, Ste Yriex-la-Perche, Nort-sur-Erdre, Cuiseaux, blois, Chateaudun, Beaugency, Brandeau, MaconVoreppe ;

Tunisie : Choutrana (80.000m3/h), Sousse Nord (50.000m3/h)

 

 

LANODOR® biofilter at the Waste Water Station of Bormes les mimosas (F)

 

 

 

 

 

 

 

LANODOR® biofilter + activated carbon polishing filter at the Waste Water Station of Les Sables d’Olonne (F)

 

 

 

 

 

 

 

LANODOR® biofilter + oxido-basic washer at the Waste Water Station of Les Sables d’Olonne (F)