Gas Emission Control - Mathematics and Statistics for the Environment - page 447

16 Gas Emission Control
Be it known to all within the sound of my voice, whoever shall be found guilty of burning coal shall
suffer the loss of his head.
—King Edward II
16.1 INTRODUCTION
Limiting gaseous emissions into the air is both technically difficult and expensive. Although rain
is Nature's vacuum cleaner—the only air-cleansing mechanism available—it is not very efficient.
Good air quality depends on pollution prevention (i.e., limiting what is emitted) and sound engi-
neering policies, procedures, and practices. The control of gaseous air emissions may be realized in
a number of ways. In this chapter, we discuss many of these technologies and the sources of gaseous
pollutants emitted from various sources and their control points (see Figure 16.1). The applicability
of a given technique depends on the properties of the pollutant and the discharge system. In making
the difficult and often complex decision of which gaseous air pollution control to employ, it is help-
ful to follow the guidelines based on experience and set forth by Buonicore and Davis (1992) in their
prestigious engineering text, Air Pollution Engineering Manual . Table 16.1 summarizes the main
techniques and technologies used to control gaseous emissions. After defining key air emission and
pollution terms, we discuss the air control technologies given in Table 16.1. Much of the informa-
tion contained in this chapter is adapted from Spellman (1999) and USEPA (1981). The excerpted
materials have been rearranged and edited to make the materials more concise for the reader's use.
16.2 DEFINITIONS
Absolute pressure —The total pressure in a system, including both the pressure of a substance
and the pressure of the atmosphere (about 14.7 psi, at sea level).
Acid —Any substance that releases hydrogen ions (H + ) when it is mixed into water.
Acid precipitation —Rain, snow, or fog that contains higher than normal levels of sulfuric or
nitric acid, which may damage forests, aquatic ecosystems, and cultural landmarks.
Acid surge —A period of short, intense acid deposition in lakes and streams as a result of the
release (by rainfall or spring snowmelt) of acids stored in soil or snow.
Acidic solution —A solution that contains significant numbers of (H + ) ions.
Airborne toxins —Hazardous chemical pollutants that have been released into the atmosphere
and are carried by air currents.
Albedo —Relectivity, or the fraction of incident light that is reflected by a surface.
Arithmetic mean —A measurement of average value, calculated by summing all terms and
dividing by the number of terms.
Arithmetic scale —A scale is a series of intervals (marks or lines), usually made along the side
or bottom of a graph, that represents the range of values of the data. When the marks or
lines are equally spaced, it is called an arithmetic scale.
Atmosphere —A 500-km-thick layer of colorless, odorless gases known as air that surrounds
the Earth and is composed of nitrogen, oxygen, argon, carbon dioxide, and other gases in
trace amounts.
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