Modeling the behavior of ethanol and BTEX in groundwater contaminated with ethanol-85

Abstract

The increased usage of ethanol, both as a biofuel and as an oxygenate, has heightened concerns about the possible negative effects of ethanol on the environment. In this thesis several conceptual models are constructed to investigate the effects of a controlled release of 200L E85 (i.e. 85% ethanol and 15% gasoline by volume) in the unsaturated zone as part of field experiments carried out by the Federal University of Santa Catarina, Florianopolis, Brazil. Using temperature and rainfall data, the models were used to investigate the effects of water table oscillations on the spreading of E85. Results from the numerical simulations using the HYDRUS-1D software package indicate that without water table fluctuations, ethanol and BTEX are retained mostly in the unsaturated zone. In agreement with experimental data by Schneider (2012), model predictions further indicate that water table oscillations cause ethanol to migrate to greater depths in the saturated zone. A sensitivity analysis is carried out to investigate the effects of several physical and chemical parameters on the transport calculations, as well as the presence of a plastic cover placed on top of the field site. Suggestions for future numerical studies are given also.