Salts (i.e. NaCl) and hydrocarbons are common soil pollutants found at contaminated sites generated by the oil and gas industry, and such pollutants pose serious risks to the environment and human health. In this study, a series of laboratory experiments were conducted to identify the properties influencing interactions of crude oil, dissolved salt, and soil particles and to evaluate the effectiveness of ultrasonic technology as a useful remediation technique for treating mixed soil contaminants. A sample of soil (sand, clay and muskeg) equivalent to 30 ml volume was spike with 1 to 2% of crude oil (volume: volume). Two salinity categories (no salt and 0.14 M salt added) were selected and the soil slurry was irradiated for up to 40 minutes using a 20 kHz ultrasonic probe operating at an intensity of 400 W/m². The change in crude oil concentration was measured in treated samples by gas chromatograph. The results indicated that the application of ultrasound generally increased the removal of hydrocarbons by a maximum of approximately 50% observed in sand. In contrast, the presence of salt significantly reduced the removal of hydrocarbons.
Historical observed data and future climate projections provide enough evidence that water resources systems (i.e., surface water and groundwater) are extremely vulnerable to climate change. However, the impact of climate change on water resources systems varies from region to region. Therefore, climate change impact studies of water resources systems are of interest at regional to local scales. These studies provide a better understanding of the sensitivity of water resources systems to changes in climatic variable (i.e., precipitation and temperature), and help to manage future water resources. In addition to climate change, human-induced land use changes also significantly affect water resources systems. Therefore, climate and land use changes can provide offsetting and additive impacts on water resources systems depending on the region and watershed characteristics. In this dissertation research, groundwater-surface water (GW-SW) interaction under the effects of climate and land use changes were investigated through the development of a Gridded Surface Subsurface Hydrologic Analysis (GSSHA) modeling system using a case study in Kiskatinaw River watershed (KRW), British Columbia, Canada. --Leaf i.
Oily sludge is one of the most significant wastes generated in the petroleum industry. It is a complex emulsion of various petroleum hydrocarbons (PHCs), water, metals, and fine solids. Due to its hazardous nature and increased generation quantities around the world, the effective treatment of oily sludge has attracted widespread attention. The complexity of its composition and diversity of its origin sources make oily sludge management a difficult and costly undertaking. Many methods have been developed for the treatment of oily sludge through oil recovery or sludge disposal approaches, but no single specific process can be considered as a panacea since each method is associated with different advantages and limitations. Efforts should focus on the improvement of current technologies and the combination of oil recovery with sludge disposal in order to comply with both resource reuse recommendations and environmental regulations. The object of this study was to develop novel combined methods for oil recovery treatment on different refinery oily sludges. The investigation focused on the oil recovery performance of combined methods based on four individual treatment processes including ultrasonic irradiation, solvent extraction, freeze/thaw, and pyrolysis in oily sludge treatment. "~The results of this research indicate that the combined oil recovery methods have the potential to be applied for the treatment of different complex oily wastes in petroleum refining industries to meet sustainable development principles. --Leaves 2-5.
Bioremediation has been recognized as an effective method to treat petroleum hydrocarbon pollutants. However, the biodegradation of crude oil contaminated sludge could be a time-consuming and low-efficiency process. One of the reasons is that petroleum hydrocarbons in the sludge are unavailable for utilization by microorganisms. Surfactants have the potential to increase the bioavailability of such pollutants due to their capability of reducing the surface and interfacial tension and increasing the solubility of hydrocarbons in water. In this study, the production of biological surfactants during sludge bioremediation was observed using surface tension measurement method, and this would provide valuable information for developing an effective bioremediation process. The addition of two different chemical surfactants (Igepal CO-630 and Cedephos FA-600) and a biosurfactant (Rhamnolipids) were tested using a laboratory respirometer, and the effects of such surfactants on the biodegradation of total petroleum hydrocarbons (TPH) in the oil refinery sludge were investigated. All surfactants were found to be effective for improving microbial growth at low concentration. Igepal CO-630 at 400 mg/kg, Cedephos FA-600 at 400 mg/kg and Rhamnolipids at 200 mg/kg were found most effective in improving the reduction of TPH (C10-C50) compared to the control sample without any addition of surfactants. Better oxygen availability to soils contaminated with hydrocarbon sludge enhances both microbial growth and TPH reduction in the samples when surfactant concentrations were optimized. --P.i.
Oil refinery sludge can be generated throughout the oil production process. It consists of a large amount of petroleum hydrocarbons (PHCs) and other hazardous materials which should be disposed of appropriately. In order to find effective methods to treat the oily sludge, three different approaches were investigated in this research, including bioremediation, oil recovery, and advanced oxidation processes (AOPs). In terms of the bioremediation approach, the oily sludge was mixed with soil, and a screened bacterium strain was then introduced with the supplement of nutrients and the addition of bio-surfactant. The reduction rate of total petroleum hydrocarbons (TPH) in oily sludge spiked soil was up to 50.8% after 40 days of biodegradation. With regard to recovering oil from the oily sludge, three processes were investigated, including ultrasonic treatment alone, freeze/thaw treatment alone, and the combined ultrasonic and freeze/thaw treatment. The experimental results revealed that the combined process could achieve satisfactory performance of oil recovery. In terms of the advanced oxidation processes (AOPs), the ultrasonic treatment alone, the Fenton process alone, and the combination of ultrasound and Fenton's reagents, were examined for their abilities to reduce petroleum hydrocarbons (PHCs) content in oily sludge. The Taguchi experimental results indicated that the combination of ultrasound and Fenton reagents achieved the best effect, with the highest TPH reduction rate of 88.1% being observed in the experimental conditions. --Leaf ii.
Drill cuttings are generated during the exploration and extraction of oil and natural gas. Due to the use of oil-based muds (OBMs) during drilling process, large amounts of oil-based drill cuttings (OBDCs) are produced. Such hazardous waste contains a relatively high content of petroleum hydrocarbons (PHCs). The effective removal of PHCs from OBDCs has attracted widespread attention since oil contaminants have severe impacts on the plant and animal ecosystem including human health (e.g., carcinogenesis and mutagenesis). Low-temperature thermal desorption (LTTD) treatment which both achieves relatively complete PHCs removal and keeps soil health at the maximum extent represent a feasible and promising method for the remediation of OBDCs. In this study, a bench-scale apparatus was used for the LTTD treatment of OBDCs with different PHCs contents... .
The mixed soil contamination of salts and petroleum hydrocarbons has become a worldwide concern since these pollutants can cause serious environmental and human health problems. An advanced remediation method -- ultrasonic enhanced soil washing was evaluated for its ability of remediating such contamination. The impacts of five factors including initial total petroleum hydrocarbon (TPH) concentration, salinity, soil type, ultrasonic treatment time and soil washing flow rate were investigated through experimental design using orthogonal arrays, and the results indicated that all these factors could significantly affect the treatment performance. Two mechanisms of ultrasonic soil remediation of TPH were proved to be desorption and degradation. The combination of ultrasound and soil washing successfully enhanced the TPH removal and the best treatment efficiency at optimized conditions was 96.17 ± 3.56%. The application of soil washing in ultrasonic treatment greatly reduced the negative effect of salt. --P. ii.
Selection of a proper remediation alternative is an important task in the decision making process of contaminated site management. The number of available remediation alternatives is increasing over the years as a result of perpetual development in scientific research. Decision makers face a confounded situation to select the best acceptable alternative by satisfying various preferences of different stakeholders (e.g., industry, government, public_. In this research, a fuzzy multi-criteria decision analysis (FMCDA) approach was developed. Since most information available in the decision making process is not deterministic, fuzzy-set theory was used to deal with such uncertainty. The developed FMCDA approach ranks the candidate alternatives according to the utility value which then assists decision makers in selecting more proper remediation options. Different stakeholders' opinions were effectively incorporated in the developed approach, allowing for a robust decision making for contaminated site management. A user friendly decision support system based on the FMCDA approach was also developed in this research. The developed method was then applied to the management of a site in northern British Columbia to examine its applicability. As well, existing multi-criteria decision making methods were also applied to the remediation selection of this site. The results suggest that the developed FMCDA method is more capable of considering uncertainty issues and it is a helpful means of integrating various interests from different stakeholders.
