BIOFILTRATION - A PROMISING AND COST-EFFECTIVE CONTROL TECHNOLOGY FORODORS, VOCS AND AIR TOXICS

Biofiltration, a relatively recent air pollution control technology, h as been identified as a promising method of odor, VOC and air toxic re moval form waste-gas streams because of low capital and operating cost s, low energy requirements and an absence of residual products requiri ng further treatment or disposal. Biofiltration units are microbial sy stems incorporating microorganisms grown on a porous solid media like compost, peat, soil or mixture of these materials. The filter media an d the microbial culture are surrounded by a thin him of water called b iofilm. Waste-gases containing biodegradable VOCs and inorganic air to xics are vented through this biologically active material, where solub le contaminants partition into the liquid film and are biodegraded by the resident microorganisms in the biofilm. The technology has been su ccessfully applied to a wide range of industrial and public sector sou rces for the abatement of odors, VOCs and air toxics, with an eliminat ion efficiency of more than 90%. Owing to its economic advantage over the conventional air pollution control methods coupled with environmen tal benefits like low energy requirements and the avoidance of cross-m edia transfer of pollutants, biofiltration is becoming more popular an d practical in meeting the statutory emission regulations. The study p resents an overview of the historical development and present status o f bio-filtration; summarizes its basic requirements, engineering funda mentals, operating principles, applicability, cost-effectiveness and p otential failures.