Uncontrolled Emission Rates (Maximum Hourly in Pounds/Day)
The TOXCHEM+ model considers the fate of the wastewater VOCs due to volatilization, biodegradation, and adsorption onto solids. The model predicts the mass of each organic compound lost and/or emitted through volatilization, biodegradation, and adsorption from each unit operation analyzed. It is able to estimate emissions from complex treatment configurations such as weirs, and aerated processes. The emission data obtained by the TOXCHEM+ for maximum one hour averaging time in pounds per day is given by the table. Notice that the aeration tank produces the maximum amount of VOC emissions. This is due to air stripping. Also notice that as the pollutant moves through the plant less is emitted because the wastewater contains less pollutant due to prior emissions; VOC concentration in the wastewater is moving toward its equilibrium concentration hence lowering the tendency to volatilize.
The meteorological data chosen was one year (January to December 1993) of hourly surface and upper air data taken from JFK International Airport. The surface air data includes wind speed, wind direction, and ambient air temperature; the upper air data includes atmospheric stability category (numbered one through six) and mixing height.
Given Source and Meteorological Data one can now determine the ambient air concentration of each Priority VOC from the emission data table. The user would have to run the ISC2 model separately for each compound. Choosing the compound Trichloroethylene from the emission data we will determine its ambient air concentration at ground level over the boundary area previously discussed.
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