Air | Biotrickling filter

Biological air treatment: biotrickling filter

Application

Odour removal
Removal of volatiles:
- sulphur and chlorinated compounds (H₂S, chloromethane,…)
- aromatics (toluene, styrene,…)
- ketones
- others (aldehydes, esters, amines, nitrogen compounds, …)

Principle

In a biotrickling filter, both the absorption and the biodegradation of the volatiles takes place in a packed bed column. The column is filled with an inert carrier material as e.g. plastic rings, lava stones,… Upon inoculation of the biotrickling filter with biosludge or a suited microbial culture, the microorganisms will feed on the target pollutants and will produce a biofilm on the surface of the carrier. The packing material is wetted in a continuous or intermittent way, and this with fresh water or with water that is recirculated. In the latter case, nutrients (nitrogen, phosphorus, ...) and acid/base (pH-adjustment) can be added to the circulating water in order to optimise the biodegradation.

This biotechnique is suited for the removal of volatiles with a rather high Henry constant. The possibility to control the pH of the circulating scrubber liquid makes this technique very useful for the removal of volatiles creating acid metabolites upon biodegradation, as e.g. volatile sulphur and volatile chlorinated compounds.

Attention should be paid to prevent clogging of the packing due to excess biomass growth. Several control strategies can be used, as e.g. nutrient limitation, predation by higher organisms as protozoa, periodic backwashing or chemical washing, periodic drying out of the biomass by stopping the wetting,….

Scheme

Scheme biotrickling filter