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Treatment of steam assisted gravity drainage produced water using polymeric membranes
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- Author / Creator
- Hajinasiri, Javad
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Steam assisted gravity drainage (SAGD) method is the main oil extraction method in Alberta that produces a huge volume of waste water. This thesis is focused on investigating the viability of membrane processes, as emerging water treatment technologies, for treatment of SAGD produced water. Three different types of membranes including ultrafiltration (UF), nanofiltration (NF), and reverse osmosis (RO) were first used in a cross-flow filtering process with the intent to remove silica, salt, and dissolved organic matter (DOM) from warm lime softener (WLS) inlet water. All Experiments were conducted at the same initial permeate flux and feed flow rate to rationalize fouling behavior of membranes by their different hydrophilicity, zeta potential and roughness. The result showed that membranes with higher hydrophilicity and more negatively charged surfaces have lower tendency to fouling. Both RO and tight NF membranes showed higher total dissolved solid (TDS) and total organic carbon (TOC) rejections (<86%) in comparison with UF (<20% and <50% TDS and TOC rejections, respectively). NF with loose membrane removed <70% of salt and DOM. Applied trans-membrane pressures to obtain 20 GFD initial water flux for RO, tight NF, loose NF and UF were 120, 80, 40 and 30 psig, respectively. Since in membrane processes the applied pressure is directly related to energy consumption, NF with tight membranes was found to be a promising candidate for treatment of WLS inlet water which removed as high amount of salt and DOM as RO but consumed less energy than RO. Hence, a tight NF membrane is suggested for further experimental investigations.
In the second part, the performance of a tight NF membrane (NF90) for inorganic contaminants polishing and DOM removal from a model SAGD boiler feed water (BFW) was investigated thoroughly. A model BFW, prepared by diluting SAGD boiler blowdown (BBD) water obtained from a SAGD plant in northern Alberta. Experiments were conducted at a temperature of 50 C and at pH values of 10.5 (the typical BFW pH used in operating plants) and 8.5. Feed pH reduced to 8.5 to investigate the effect of pH reduction, and subsequently precipitation of silica and DOM and deposition on the membrane surface on the flux decline. Decreasing the pH from raw water pH (10.5) to 8.5 decreased the water flux reasonably and increasing the pH back to 10.5 recovered the water flux. It is proposed in this study that a pH pulsation technique can be used to reduce the membrane fouling and recover the water flux. Throughout the study, fouled membranes, feed produced water and permeate were characterized to characterize the deposited materials on the membrane which were responsible for fouling. The presence of both organics (primarily carbon and oxygen) and inorganics (mainly silicon, calcium and iron) in the fouling deposits was confirmed by surface characterization techniques. Characterization of feed and permeate feed and permeate showed that the organic matter that passed through the membrane was mainly hydrophilic compounds. A suitably designed crossflow NF process is demonstrated be a superior alternative technique to current SAGD produced water treatment methods, especially in terms of producing higher quality water by consuming lower amount of chemicals and energy. -
- Subjects / Keywords
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- Graduation date
- Spring 2015
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- Type of Item
- Thesis
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- Degree
- Master of Science
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- License
- This thesis is made available by the University of Alberta Libraries with permission of the copyright owner solely for non-commercial purposes. This thesis, or any portion thereof, may not otherwise be copied or reproduced without the written consent of the copyright owner, except to the extent permitted by Canadian copyright law.