Semester of Graduation
Master of Science in Civil Engineering (MSCE)
Civil and Environmental Engineering
The release of MC252 crude oil following the Deepwater Horizon event has emphasized the need to investigate factors controlling the extent of contamination degradation in coastal environments. Dam structures created on Fourchon Beach, LA established conditions for PAH and n-alkane accumulation and burial along a vertical profile that persists today due to the anaerobic, often anoxic, and hypersaline conditions of the groundwater. The ability to remove the oxygen limitation present on in situ aerobic biodegradation of buried petroleum-based hydrocarbons in this environment was investigated through the coupled process of chemical oxidation and enhanced bioremediation using a proprietary formulation of activated persulfate and oxygen-release compound. To better understand the interactions of the chemical oxidant with the subsurface and to determine its compatibility with further bioremediation, bench and field-scale treatments were conducted in order to evaluate the efficacy the coupled process. Degradation of PAH and n-alkanes during field treatment were monitored in beach sediment and quantified through GC-MS. Results indicated that chemical oxidation with persulfate directly oxidized a differential portion of PAH and n-alkanes through a variety of non-specific reactions while satisfying a portion of the oxygen demand, indicated by sustained concentrations of dissolved oxygen following addition of oxygen-release compound. In spite of perturbations to groundwater, resilience of the microbial population was observed after the first phase of chemical oxidation, with a final increase in diversity as determined by next generation DNA sequencing. Laboratory studies were conducted to determine the oxygen demand exerted by buried crude oil and reduced chemical species before and after treatment and to further assess the extent of direct degradation from chemical oxidation. Results from this research can lead to an improved understanding of the limitations associated with applying aerobic bioremediation strategies for oil degradation in oxygen-limited environments.
Bramlet, Olivia, "Coupled Chemical Pre-Oxidation and Aerobic Bioremediation of Buried MC252 Oil Across a Headlands Beach Profile" (2018). LSU Master's Theses. 4816.
Available for download on Friday, October 18, 2019