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Integrated Chemical/Membrane Treatment for Oil Sands Produced Water
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- Author / Creator
- Mohammadtabar, Farshad
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Over the last decade, the treatment of the produced water streams from steam assisted gravity drainage (SAGD) operation has attracted a significant attention. In this study, an integrated method based on the membrane filtration and chemical treatment was proposed for the treatment of the boiler blow-down (BBD) water. First, the potential application of ion exchange regeneration wastewater (IERW), containing high concentration of magnesium ions, to act as a coagulant for the treatment of BBD water was investigated. Conventional techniques for the treatment of BBD water require significant operational costs as they rely on the extensive use of chemical coagulants. Since the proposed process design in this study uses another wastewater stream of a SAGD plant, operational costs and energy consumption are predicted to be minimized. The effects of temperature, the mixing ratio of BBD water and the IERW, and the stirring intensity on the removal of organic matter and dissolved minerals were investigated. Utilizing IERW as a coagulant enhanced the removal of impurities; removal efficiency of 81.1% and 98.6% were obtained for organic matter and silica, respectively. The treatment of BBD water by IERW, however, has led to an increase in the concentration of calcium in the effluent, which was effectively mitigated by soda ash softening. Furthermore, resource recovery from the coagulated sludge was explored by chemical methods of characterization, and it was revealed that the precipitated compounds were mostly composed of calcium, magnesium, and silica. In conclusion, the IERW water proved to be highly effective in removing contaminants from SAGD produced water. In the next step, different membrane-based hybrid processes were applied to further purify the treated BBD by IERW. The first scenario studied the usage of soda ash softening to reduce the calcium concentration, followed by nanofiltration (NF). It was observed that using soda ash softening as a chemical pre-treatment for the NF can reduce the deposition of calcium on the surface of the membrane. Second scenario involved direct treatment of the BBD water using NF and then purifying the NF retentate using an integrated IERW conditioning and NF process. The filtration of BBD water demonstrated a relatively low total flux decline ratio due to having a low TDS concentration and the treated water resulted from the IERW conditioning of concentrated BBD showed a relatively low concentration of calcium. Third scenario was to investigate the potential of using the IERW as the draw solution of forward osmosis (FO) for the treatment of the BBD. However, the NF of diluted IERW was inefficient in terms of requiring a higher operating pressure to purify this wastewater. The effectiveness of these methods was compared based on flux recovery ratio and contaminants removal efficiency. The direct NF of BBD followed by another cycle of IERW conditioning and NF was found to be the optimum scenario regarding water recovery and water product quality.
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- Graduation date
- Spring 2019
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- Type of Item
- Thesis
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- Degree
- Master of Science
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- License
- Permission is hereby granted to the University of Alberta Libraries to reproduce single copies of this thesis and to lend or sell such copies for private, scholarly or scientific research purposes only. Where the thesis is converted to, or otherwise made available in digital form, the University of Alberta will advise potential users of the thesis of these terms. The author reserves all other publication and other rights in association with the copyright in the thesis and, except as herein before provided, neither the thesis nor any substantial portion thereof may be printed or otherwise reproduced in any material form whatsoever without the author's prior written permission.