Biofiltration: A promising and cost-effective control technology for odors, VOCs and air toxics

Biofiltration, a relatively recent air pollution control technology, has been identified as a promising method of odor, VOC and air toxic removal form waste-gas streams because of low capital and operating costs, low energy requirements and an absence of residual products requiring further treatment or disposal. Biofiltration units are microbial systems incorporating microorganisms grown on a porous solid media like compost, peat, soil or mixture of these materials. The filter media and the microbial culture are surrounded by a thin him of water called biofilm. Waste-gases containing biodegradable VOCs and inorganic air toxics are vented through this biologically active material, where soluble contaminants partition into the liquid film and are biodegraded by the resident microorganisms in the biofilm. The technology has been successfully applied to a wide range of industrial and public sector sources for the abatement of odors, VOCs and air toxics, with an elimination efficiency of more than 90%. Owing to its economic advantage over the conventional air pollution control methods coupled with environmental benefits like low energy requirements and the avoidance of cross-media transfer of pollutants, biofiltration is becoming more popular and practical in meeting the statutory emission regulations. The study presents an overview of the historical development and present status of bio-filtration; summarizes its basic requirements, engineering fundamentals, operating principles, applicability, cost-effectiveness and potential failures.