Biofilters
Biofilters are used for the removal of volatile organic compounds (VOC), odor components and inorganic compounds (NH3, H2S). This technology uses micro-organisms to biodegrade air pollutants.
During this process, the polluted air is sent through a porous bed of filter material. Common materials include compost, coconut shells, bark,… To prevent drying of the filter bed, the air is typically pre-moistened in an upstream spray tower. By spraying the filter periodically with water, a thin film of water arises on the filter material in which the growth of micro-organisms takes place.
These micro-organisms extract the required nutrients from the filter material, which basically serves as a carrier for the bacterial population. The microbiological activity may be further optimized through the addition of appropriate nutrients and minerals to the spray water.
Once the biofilter is installed, the operating parameters must be monitored to ensure proper operation of the installation. In order to prevent acidification of the filter bed, a pH buffer can be dosed to the spray water. Acidifying components may also be removed by an upstream chemical scrubber in which the biofilter takes care of the further degradation of the contaminants. The filter material needs to be replaced after about 2-3 years.
| Advantages: | Industries: |
| - Low investment and operating costs | - Water treatment installations |
| - Simple construction | - Compost plants |
| - Optimal removal of biodegradable components | - Foundries |
| - Low pressure drop | - Chemical industry |
| - Few waste water | - Plastics manufacturing |
| - Few waste material | - Food industry |
| - Flavoring industry | |
| - ... |
