Pollution Engineering - January 2009 - (Page 24)

Emitting EDUCATION A simply constructed, ar tiﬁcial smokestack safely simply constructed, artiﬁcial smokestack safely r pollutants . demonstrates the dispersion of toxic air pollutants. By ANTHONY J. SADAR, CCM earning the concepts of air pollution dispersion for the first time can be quite challenging. Even if the qualitative portions of the topic are not so hard to grasp, the quantitative, formulaic parts can be downright intimidating. One method educators and trainers can use to break through such barriers is a physical modeling tool, labeled The SuperStack by the author, which realistically and safely demonstrates the dispersion of atmospheric contaminants using paper hole-punches to represent pollution particles. The artificial stack is 13 feet tall with a uniform 4-inch inside diameter, but can be used to provide practical, hands-on experience for stacks of a much grander scale. L air’s mixing potential U = wind speed (m/s), critical weather condition related to downwind transport of contaminants. Scientists and engineers who study air pollution dispersion will frequently rely on a basic Gaussian plume equation, derived from empirical studies and statistical analysis, e.g. probability density function, to quantitatively estimate the concentration of atmospheric contaminants downwind of an emission source. A simplified version of the Gaussian plume equation follows: Modeling theory The three primary components of the air pollution system (elaborated on later) are emission sources, the atmosphere and receptors of contaminants. The unifying formula for the relationship among these components is: Where: C = concentration (g/m3), the impact of the source(s) on the receptor(s) Q = emission rate (g/s), the contaminant quantity/time release into the atmosphere S = stability (m-2), a critical weather condition related to the 24 Pollution Engineering JANUARY2009 Where: = contaminant concentration in the atmosphere (g/m3) at a specified downwind distance q = uniform, continuous emission rate (g/s) π = 3.1416 u = average wind speed (m/s) in the atmosphere downwind of the source y = cross-wind dispersion parameter (m) at a specified downwind distance z = vertical dispersion parameter (m) at a specified downwind distance H = emission height (m). (Note that “exp” is typically designated as “ex ” on calculators. Basically, such equations are developed to approximate a downwind concentration (mass of a contaminant in a volume of air, typi-

Table of Contents Feed for the Digital Edition of Pollution Engineering - January 2009

Pollution Engineering - January 2009 Contents The Editor’s Desk EnviroNews PE Events Legal Lookout Green Connections Ten Top Technologies for 2009 Old Fashioned Chemistry Emitting Education NGWA Reports from Its Annual Meeting A Wood and a Pond Company Technical Profiles Filtration/Membrane Products Flow and Level Monitoring Equipment Classified Marketplace Advertisers Index State Rules

Pollution Engineering - January 2009

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