Biotrickling

Absorption and biodegradation in one packed bed

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 materialsuch as plastic rings, lava stones,… Upon inoculation of the biotrickling filter with biosludge or a suitable 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, using either fresh water or recirculated water. 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.

Suitable for specific volatiles

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 that generate acidic metabolites during biodegradation, such as volatile sulphur and volatile chlorinated compounds.

Preventing clogging and biomass growth

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