Biofiltration is an air pollution control technology. It is essentially a packed bed of particles in which microorganisms are immobilized on top of the packing particles called support medium. The contaminated air stream (pollutants such as ammonia, amines, hydrogen sulfide (H₂S), reduced sulphur compounds (RSC), and/or VOCs) is humidified and passed through the bed. There are minimal requirements for energy and raw materials and minimal waste production. In particular, biofiltration has become an accepted and mature technique for air pollution control with substantial industrial confidence. This is demonstrated by the exponentially increasing number of biofilters around the world. Biofiltration is successfully being used in a variety of applications in North America including wastewater treatment plants, food processing plants, composting & organics processing facilities, rendering plants, fertilizer plants and pulp & paper industries, for odour control, sewage air treatment, ATAD off gas treatment and VOC emission control (BTEX control).