ABSTRACT

A biofilter consists of a bed of soil or compost beneath, which is a network of perforated pipe. Contaminated air flows through the pipe and out of the many holes in the sides of the pipe, thereby being distributed throughout the bed. A biofilter works by providing an environment in which microorganisms thrive. The organic substrate provides the salts and trace elements for the bacteria, and the volatile organic compounds (VOC) provides the food source. This action is an adaptation of biogdegradation in which the air cleanses itself naturally. The microorganisms are the same that degrade organic wastes in nature and in wastewater treatment plants. These microorganisms in a moist environment oxidize organic compounds to CO2 and water. The soil or compost beds provide a network of fine pores with large surface areas. In soils, the pores are smaller and less permeable than in compost. Therefore, soil requires larger areas for biofiltration.