Volatilization and bioremediation potential of soil contaminated by petroleum products
Prior studies at Iowa State University tend to indicate that petroleum products such as gasoline, diesel fuel, and crude oil can be removed from soil by bioremediation. These studies also indicate that gasoline would largely be removed by volatilization and that diesel fuel would not. The purpose of my research was to investigate volatilization as a competing process for the removal of fuels with bioremediation. If the rate of removal by volatilization is fast enough, biological processes might only make a small contribution to the overall removal that is observed. If the rate of removal by volatilization is slow enough, biological processes would make the major contribution to the overall process;In my research, several factors were investigated for their effect on volatilization in order to develop the mathematical model and predict the fate of petroleum products in sand. These effects include particle size, initial concentration of petroleum products, moisture content, and organic matter used for bioremediation agents. Results indicate that these factors did not play a significant role in volatilization of petroleum products in sand;These results also provided a basis for modeling the volatilization process. One of the models was a material balance model developed as a part of this study. The other was a published model based on a heat transfer analogy. The model based on the heat transfer analogy did a very poor job of fitting the data whereas the material balance model fit the data better. In addition to having value in predicting rates of volatilization, the material balance model explains why the rate of volatilization for gasoline is so much higher than it is for diesel fuel. Both models recognize that volatilization is driven by the vapor gradient that is developed in the pore space. The material balance model also accounts for the volatility of the fuel and the part it plays in establishing the vapor gradient that drives volatilization.