BBK-biofilters are built so that the polluted air is led through the filter media, either upwards or downwards. Often the polluted air is mixed with air from room-ventilation before entering the biofilter. As the air passes through the filter media, specific micro-organisms will decompose the odorous compounds into CO2 and water. The detention time can vary, but it is typically 25-35 sec. depending on the complexity of the odorous compounds.

The filter media has a height of 1 meter. The filter media is humidified by means of a sprinkler system, as it is important to control the humidity to obtain maximum cleaning effect.

In addition to the humidity it is also important to control the temperature in the filter to ensure maximum capacity and cleaning effect. The micro-organisms in the biofilter cannot stand too high temperatures, but conversely too low temperatures will result in reduced efficiency. Inlet air temperature must not exceed 40o C before entering the airfilter.

The BBK-filter media is different from traditional filter media, as it consists of non-biodegradable compounds. This means that the filter media will not be transformed into soil as time goes by, but will remain porous and homogenous for many years.

The filter media is pasteurised at 80oC for a period of 30 minutes to ensure that all bacteria, fungi etc. are eliminated. Subsequently the filter media is inoculated with specific micro-organisms selected for the individual types of industry.

The pasteurising and the following inoculation have in view to obtain the largest possible activity of the micro-organisms which are able to decompose the odour, and not to leave any room for non-active nor harmful organisms. This will result in a far better odour removal than in even well-acting traditional biofilters.