Air biofilters use microorganisms to capture and biologically degrade air pollutants and output pure, filtered air. They are often used for treating malodorous compounds and water-soluble, volatile organic compounds (VOC) in wastewater applications, chemical plants, and oil well operations. Air biofilters are also commonly employed by industries such as food and drink, pharmaceuticals, wood product manufacturing, and paint, coatings, and resin applications.
The biofiltration process includes degradation of compounds in the filter, and a pre-treatment humidification system. Pollutants contact the biofilter media and are transferred from the air phase to a water phase. When in the biofilter section, a thin, biological film surrounds each media particle. Within this film are bacteria, which biologically oxidize the VOCs and odorous compounds and converts them into carbon dioxide and water.
When using air biofilters, the biggest challenge can be maintaining the correct amount of moisture throughout the system. Air is typically humidified before entering the filter bed with a watering system (spray), a humidification chamber, bioscrubber, or biotrickling filter.
Air biofilters may use organic packing media such as peat, vegetable mulch, or wood chips for humidification purposes, or a combined natural and synthetic component. Systems using solely organic media may last for several years, while the combined material systems will generally last much long. Depending on the company, some may offer multi-year guarantees on their air biofiltration systems.