Common Vapor Treatment Technologies

Biofiltration

Biofiltration is a low-cost an effective air pollution control (APC) technology in which vapor-phase organic contaminants are passed through a bed of porous media. The contaminants transfer into the water and biofilm on the surfaces of the media where they are degraded by microorganisms. Most biofilters are operated under non-sterile conditions so that it is possible for microorganisms capable of degrading the compounds to enter the biofilter through the airstream. Most commonly biofilters are seeded with mixed cultures from a source known to have the contaminants of interest such as a wastewater treatment plant. Specific strains of bacteria may also be introduced into the filter and optimal conditions provided to preferentially degrade specific compounds. Biofiltration as a term encompasses biofilters and bioscrubbers.

Biofilters provide several advantages over conventional granular activated carbon adsorbers. First, bio-regeneration keeps maintains the capacity available so that a biofilter does not require regeneration. These features reduce capital and operating expenses. Additionally, the contaminants are destroyed not just separated, as with granulated activated carbon (GAC) technologies. Commonly in treating toxic compounds a biofilter will be used in series with an activated carbon bed. The biofilter can greatly reduce the consumption of carbon and the carbon bed can prevent release of contaminants in case there is an upset of the biological activity. Biofiltration is not applicable for all chlorinated solvents, has a limited history of application at full-scale for treating compounds such as PCE and TCE, and has shown inconsistent results for those types of compounds in demonstration studies.

Figure 1: Three biofilter units operating in parallel at a remediation site. Photo provided courtesy of Matrix Environmental Technologies Inc., copyright 2002. http://www.matrixbiotech.com/html/biofilter.html

Biofilers have most frequently been use for nonhalogenated VOCs and SVOCs, and fuel hydrocarbons. (Portions of this Summary were adapted from the Federal Remediation Technologies Roundtable.)

For more detail regarding biofiltration, click on the following link to the Federal Remediation Technologies Roundtable FRTR Section 4 - Biofiltration.