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3
Bioreactors
Dr. Robert Richardson
In air pollution control, bioremediation is the use of bacteria and fungi to consume
pollutants from an air stream contaminated with organic compounds that are soluble
in water or can be solubilized in water. Bioremediation also includes chemical trans-
formation for some inorganic compounds like suldes and nitrogen oxides.
3.1 DEVICE TYPES
Biolters, biotrickling lters, aerobic digesters, and bioscrubbers technologies
includes a wide range of methodologies that are applicable to a diverse spectrum of
air quality applications. Each device type has advantages and limitations. These will
be described below.
This chapter also describes recent breakthroughs in bioreactor technology and
the combination bioreactors with other air pollution abatement technologies. These
breakthroughs include the use of surfactants to expand the range of organic com-
pounds that can be treated with bioreactor methods and breakthroughs that utilize
biological organisms in temperature and pH ranges not typically used in biological
abatement of air pollution.
After dening the basic vocabularies associated with these methodologies and
outlining the fundamental requirements for their success in air quality applica-
tions, this chapter will explain some of the ways these technologies can be com-
bined with conventional air quality remediation methods to further optimize cost
and performance.
Bioremediation: Any of the processes described as follows:
Biolter: An in-ground or above-ground lter bed through which moist air at
ambient temperature containing water soluble volatile organic compounds
(VOCs) or sulfur-containing compounds like hydrogen sulde (collectively
air pollutants) pass. The bed is made from porous organic or inorganic
media that act as a substrate for bacteria or fungi. The air pollutants are
removed from the air by transfer to moisture surrounding the microorgan-
isms which are sequestered to the media bed.
Biotrickling lter: Similar in design to trickling lters used in the treatment of
wastewater but differing in application because these devices treat air laden
with pollutants described in the biolter denition above rather than pol-
lutants dissolved in a liquid. Biotrickling lters are typically round vessels
with cone-shaped bottoms and no top. A packing bed typically between 5

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