Page 58 - Air Pollution Control Engineering

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38 Lawrence K. Wang et al.

9.1.2. Airborne Contaminants
Of various airborne contaminants, organic gaseous emissions are the most important
recent focus. Air emission standards have been developed by the US Office of Air
Quality Planning and Standards (OAQPS) to address organic emissions from several
waste-management sources. The unit operations and processes for removing organic
airborne contaminants include wet and dry scrubbing, condensation, flare, thermal oxi-
dation, catalytic oxidation, gas-phase carbon adsorption, gas-phase biofiltration, and so
forth presented in Chapters 5–12.
Waste-management sources also contribute other types of air emission such as
inorganic gaseous (metals) and particulate matter (PM), which are subject to federal
regulation under other programs. This can be illustrated by the program developed by
the US Office of Solid Waste (US OSW), which has standards for metal emissions
from industrial boilers and furnaces. At landfills and hazardous waste-treatment, stor-
age and disposal facilities (TSDFs), US OSW has general requirements that limit
blowing dust (particulate matter). Additionally, the US EPA has developed the fol-
lowing document that deals with the control of emissions from TSDFs: Hazardous
Waste TSDF—Fugitive Particulate Matter Air Emission Guidance Document EPA-
450/3-89-019 (22). Fabric filtration (Chapter 2), cyclones (Chapter 3), electrostatic
precipitation (Chapter 4), and wet scrubbing (Chapter 5) are the processes for
removal of PM and inorganic contaminants (metals). The readers are referred to ref.
59 dealing with the following important subjects for removing inorganic and PM
contaminants:
1. Atmospheric modeling and dispersion
2. Desulfurization and SO /H S emission control
x 2
3. Carbon sequestration
4. Control of nitrogen oxides during stationary combustion
5. Control of heavy metals in emission streams
6. Ventilation and air conditioning.
Infectious airborne pollutants are various pathogenic microorganisms, including bac-
teria, virus, and fungus, and can be present indoors (39–41), or both indoor and outdoor
when there is a bioterrorist’s attack (49–52). Finally, radon gases are radioactive air-
borne pollutants, and noise is transmitted through air. The solutions to the problems of
airborne infectious bacteria, virus, fungus, radon, and noise can be found elsewhere (59).
9.2. Ozone
9.2.1. Ozone Layer Depletion and Protection
Depending on what part of the atmosphere contains ozone, it can either benefit or
harm human health and the environment. Figure 15 illustrates this relationship. Ozone
occurs naturally in the upper (stratosphere) and the lower atmospheres (troposphere).
Ozone in the stratosphere protects us from the sun’s radiation; ozone in the troposphere,
however, can have adverse health effects and other negative environmental impact. The
greenhouse gases are CO , H O, CH , NO , and chloroflurocarbons (CFCs), the con-
2 2 4 2
centrations of which are increasing and causing global warming. CFC gases destroy
the ozone in the stratosphere, thus reducing the ozone layer’s radiation protection
effect (20).