Master of Science

thesisWith increasing industrial activities in many parts of the world, a large amount of crude oil is being consumed daily. With the large number of offshore and onshore oil fields along with the transportation of crude oil and its products, the risk of oil spill increases accordingly. Big crude oil spill accidents have caused not only loss of the energy resource but also significant contamination to the environment and ecosystems, attracting intense attention in each occurrence. Small oil spills occur frequently, but with less notice worldwide on a daily basis on land, at sea, and throughout inland freshwater systems. Various approaches have been proposed to decontaminate oil spill sites according to individual environmental constraints. The main methods for in situ oil spill clean-up include biodegradation, controlled burning, sorption, dispersion, along with chemical oxidation, filtration, membrane process, and adsorption for lower oil concentrations. These existing methods have their own drawbacks such as long duration and harmful intermediates; new effective methods using a combination of the existing methods are necessary. In this study, a process train utilizing flotation, stage-1 sand filtration, heightened ozonation (HOT), and stage-2 sand filtration was used to deal with oil-contaminated water (2.5% oil) that would simulate oil spills under different water conditions, including tap water, Utah Lake water, and Great Salt Lake water representing fresh water, groundwater, and sea water contamination. Treatment was carried under different conditions and the optimum conditions were identified. Excellent operation flowrates were found to be 5.2, 8, and 2 cm/min for the flotation column, the first-stage sand filtration, and the second-stage sand filtration, respectively. The results showed that HOT treatment of 8 cycles at 100 psi was most effective and economical in terms of dosage for achieving desirable effluent quality (84.76% O&G removal) and sand filter's life capacity (150 times the sands volume before sands were exhausted). The new treatment train achieved 99.9 % oil and grease removal and > 99.8 % COD removal, with increased sCOD and BOD/COD ratio, which indicated the potential of further polishing biological treatment if needed

Doctor of Philosophy

dissertationGeologic CO2 sequestration (GCS) is believed to play a critical role for mitigating CO2 emissions. Many geologic carbon storage site options include not only excellent storage reservoirs bounded by effective seal layers, but also Underground Sources of Drinking Water (USDWs). An effective risk assessment of potential CO2 leakage from the reservoirs provides maximum protection for USDWs. A primary purpose of this dissertation is to quantify possible risks of CO2 leakage to USDWs, specifically risks associated with chemical impacts. Wellbore provides possible leakage pathways for CO2, and its integrity is a key risk factor for geological CO2 storage. This dissertation firstly presents an analysis on the impacts of CO2 leakage through wellbore cement and surrounding caprock with a gap (annulus) in between. Mechanisms of chemical reactions associated with cement-CO2-brine interactions are predicted, and wellbore integrity under CO2-rich conditions is analyzed with a case study example â€" the Farnsworth CO2 enhanced oil recovery (EOR) unit (FWU) in the northern Anadarko Basin in Texas. The second part of this dissertation focuses on quantification of possible risks of CO2 leakage through fractured wellbores to overlying USDWs. To understand how CO2 is likely to influence geochemical processes in aquifer sediments, a response surface methodology (RSM) with geochemical simulations is used to quantify associated risks. The case study example for this analysis is the Ogallala aquifer overlying the FWU. Increased CO2 concentrations in shallow groundwater aquifers could result in release and mobilization of toxic trace metals. This dissertation also presents an integrated framework of combined batch experiments and reactive transport simulations to quantify trace metal mobilization responses to CO2 leakage into USDWs. The mechanisms of trace metal mobilization are elucidated, and the key parameters are quantified. The case study includes elevated CO2 conditions at the Chimayo site in northern New Mexico, a natural analog with CO2 upwelling