Study of High Water Temperature Effects on Air Stripping of Volatile and Slightly Volatile Organics from Water
Packed column air stripping units have become a common method for removing volatile organic compounds (VOCs) from drinking water. The field of chemical engineering has used packed bed strippers for many years as a separation process. The theoretical aspects as well as the pertinent design equations of these stripping units can be found in most mass transfer t e x t b o ~ k s . ' ~ ~ A review of the design principles of stripping units as they apply to dilute solutions has been given by Kavanaugh and ~ r u s s e l l . ~
The two-resistance theory model, gas phase and liquid phase, can be defined by the following equation:
To model the behavior of packed towers for the removal of volatile organic compounds, two forms of the above stated equation have been used. In the single resistance model, the gas phase resistance is neglected so that KL = kp.3'4 In the two resistance models, both gas phase and liquid phase resistance are considered to o c ~ u r . ~ ~ ~ * ' Roberts et reviewed three methods to calculate the liquid phase resistance or both the liquid and gas phase resistance and compared the predicted overall mass transfer coefficients from each method to the actual measured overall mass transfer coefficients. The authors concluded the Onda eth hod' was the best of the three models evaluated. This conclusion was
recently supported by the work of Lamarche and ~ r o s t e . ~ staudingerl0 also evaluated the Onda Model concluding that the correlation was adequate for modeling the air stripping of volatile organics from contaminated water sources as part of the preliminary feasibility and design work on a treatment system. The authorI0 also stated that the accuracy value for the Onda Correlation should be placed at 30% instead of the 20% presented in the original work.