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Gas-Phase Biofiltration

Gregory T. Kleinheinz and Phillip C. Wright

CONTENTS
INTRODUCTION
TYPES OF BIOLOGICAL AIR TREATMENT SYSTEM
OPERATIONAL CONSIDERATIONS
DESIGN CONSIDERATIONS/PARAMETERS
CASE STUDIES
PROCESS CONTROL AND MONITORING
LIMITATIONS OF THE TECHNOLOGY
CONCLUSIONS
NOMENCLATURE
REFERENCES

1. INTRODUCTION
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.
Biological treatment methods have been widely used by industry to mitigate envi-
ronmental contamination throughout the 20th century. However, only recently has
biofiltration gained acceptance in the United States as a viable treatment alternative for

From: Handbook of Environmental Engineering, Volume 1: Air Pollution Control Engineering
Edited by: L. K. Wang, N. C. Pereira, and Y.-T. Hung © Humana Press Inc., Totowa, NJ
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