Gas-Phase Biofiltration

Abstract

Biofiltration is the use of microorganisms, immobilized on a biologically active solid support, to treat chemicals in an airstream. Although the term implies a physical process, the process is biochemical and will not likely be changed in the near future. Biofilters have been used for volatile organic compound (VOC) abatement, mitigation of odor-causing compounds, and in conjunction with other treatment technologies (i.e., soil vapor extraction). With recent changes in US air regulations, increased pressure has been placed on industries that emit chemicals into the air. Biofilters have been an increasingly popular choice as a treatment option because of their low operating cost and relatively low capital costs compared to other technologies. Biofilters operate under the premise that contaminants in the airstream partition into an aqueous layer on the solid support, where it is bioavailable and then degraded by the microbial community present. Complete metabolism of an organic compound yields carbon dioxide and water, which is then moved out of the biofilter. In general, conventional biofilters have been the most successful in applications with low flow rates and relatively low concentration of contaminants. Table 1 lists some of the industries that have used biofilters.