Biofiltry

Biofiltry, or biofilters, are engineered systems that remove contaminants from air or water by exploiting the metabolic activity of microorganisms immobilized on a porous support medium. Air or process water passes through the medium, allowing pollutants to diffuse into a active biofilm and be oxidized to less odorous or harmless compounds, typically carbon dioxide and water.

Common media include compost, wood chips, peat, and plastic support media. The moisture content is maintained to sustain microbial activity, often through humidification or recirculation of water.

Two main configurations are used: biofilters designed for air treatment and those for water treatment. In air biofilters, odorous VOCs and sulfur compounds are removed as the contaminated air passes through the bed; in water biofilters, inorganic and organic substances or nutrients can be removed from process water through microbial degradation.

Design options include packed-bed biofilters and biotrickling filters. Beds are kept within an optimal moisture and temperature range; empty-bed residence times vary with pollutant strength and flow rate.

Advantages include relatively low energy use compared to chemical scrubbers, ability to treat a wide range of pollutants, and the production of minimal secondary waste. Limitations include sensitivity to temperature and moisture fluctuations, potential clogging of the bed, and reduced performance at very high pollutant loads.

Common applications are odor control at wastewater treatment plants and agricultural operations, odor and VOC removal in food processing, landfill gas treatment, and indoor air purification.