Air Pollution Control Equipment Selection Guide, 2nd Edition

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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