Biodegradability of Diluted Bitumen (Dilbit)
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Biodegradability of Diluted Bitumen (dilbit) A Thesis submitted to Graduate school of University of Cincinnati In Partial Fulfillment of the Requirements for the Degree of Master of Science In the Department of Biomedical, Chemical and Environmental Engineering of the College of Engineering and Applied Sciences 2016 By Ruta Suresh Deshpande B.E. Chemical Engineering, University of Mumbai, Mumbai, India, 2012 Committee Dr. Pablo Campo-Moreno (Chair) Dr. Robyn N. Conmy Dr. George A. Sorial Abstract The share of unconventional fuel sources (oil sands, shale gas etc.) in the oil market is growing in terms of production and usage. For the past 40 years, the United States has been importing petroleum products derived from Canadian oil sands. Nevertheless, in recent times, owing to the increased demand, the proposal of pipeline expansions along with two major spills (Kalamazoo, 2010 and Mayflower, 2013), these sources are again in the limelight. Oil sands yield bitumen which is the heaviest form of crude oil. For transportation purposes, bitumen is altered either by diluting or upgrading. When bitumen is blended with lighter hydrocarbons, diluted bitumen or dilbit is produced. Its physical and chemical properties are quite different from those of conventional oils. Limited and inconsistent literature is available on the biodegradability of dilbit, thus the main aim of this research was to evaluate different aspects of its biodegradation to fill this knowledge gap. To achieve this goal various bench scale experiments were run in two phases. In phase one, two tests were carried out at 5 and 25 ºC in freshwater media with two types of dilbits, western Canadian select (WCS) and Cold Lake Blend (CLB). Cultures isolated from sediments obtained after the dredging operations on Kalamazoo River spill were enriched and used as the inoculum. The physical and chemical characteristics of WCS and CLB differed slightly, whereas their composition was significantly different from that of a conventional crude oil. The degradation rates obtained for both dilbits as well as the extent of their removal were comparable, with faster rates for the higher temperature. Phase two was a comparative study to assess biodegradation of dilbit and a conventional crude oil under several conditions. For this purpose, WCS dilbit and Prudhoe Bay Crude (PBC) i were tested. Additionally, microbial consortia obtained from two different hydrocarbon contaminated sites were used to evaluate the effect of microbial enrichments. Prior to the experimental set up, cultures obtained from Kalamazoo River (KMZ) where enriched on dilbit at 5 (cryo) and 25 (meso) ºC, while culture isolated from Ohio River (AF) was enriched at only 25 ºC. Although observed rates of alkane, polycyclic aromatic hydrocarbon (PAH), and total extractable hydrocarbon (TEH) removal were similar for dilbit and conventional crude oil, the latter degraded to greater extent. All three consortia showed diverse microbial community structure which greatly influenced degradation potential with varying temperature. Although complete alkane removal was achieved in all the treatments, the metabolism of PAH and TEH varied. The KMZ meso culture was the most efficient consortium as it metabolized most of the PAHs along with the biomarker hopane. The AF culture exhibited distinct behavior at the two temperatures with a longer assimilation time at the colder temperature, which was not the case at the warmer temperature. ii iii Acknowledgements As I fulfill my degree requirements for Master of Science in Environmental Engineering, I think of all the wonderful people who transpired a dream into reality. A dream that started three years ago, to tackle today’s environmental issues and help solving the real world problems. For that, I couldn’t thank Dr. Pablo Campo-Moreno enough for giving me an opportunity to work on projects which will make a contribution to the science and the environment. His support, compassion and guidance accompanied by his excellent scientific acumen made the journey filled with challenges and obstacles a clear path. I would like to sincerely thank Dr. Robyn Conmy for the unwavering support in the decisions we took along the way. Her presence really ensured that the focus always remained on the novelty and creativity. I am grateful to our department head Dr. George Sorial for his leadership and mentorship, which really fostered a welcoming environment and helped me to express myself. I am indebted to Dr. Devi Sundaravadivelu for being the friend, philosopher and guide in my journey. The brainstorming sessions and the scientific discussions we had were critical for achieving the goals. To quote Mr. Henry Ford “Coming together is beginning; keeping together is progress; working together is success”. The friendship and partnership I developed with my colleagues Ms. Yu Zhang, Dr. Mobing Zhuang, and Ms. Gulizhaer Abulikemu is without a doubt one of the best things happened to me during my tenure as a master’s student. I really appreciate Dr. Raghuraman Venkatapathy’s support and the efforts he put to make things easier for me. I sincerely thank Ms. Edith Holder and Dr. Jorge Santo Domingo for expertly handling the microbiology aspects of this work. iv Last but not the least, I express my humblest gratitude towards my family, friends and well- wishers for believing in me every single day. This work is dedicated to all the people who touched my life in one way or the other. v Patience does not mean to passively endure. It means to be farsighted enough to trust the end result of a process. It means to look at the thorn and see the rose, to look at the night and see the dawn. The lovers of God never run out of patience, for they know that time is needed for the crescent moon to become full. - Elif Shafak, The Forty Rules of Love vi Table of Contents Abstract .......................................................................................................................................................... i Acknowledgement ....................................................................................................................................... iv List of Figures .............................................................................................................................................. ix Chapter 1:Overview ...................................................................................................................................... 1 1.1 Background ..................................................................................................................................... 1 1.2 Oil Sands and bitumen .................................................................................................................... 1 1.4 Biodegradability of dilbit ................................................................................................................ 5 1.5 Research Objectives ........................................................................................................................ 6 1.6 Thesis Layout .................................................................................................................................. 7 1.7 References ....................................................................................................................................... 7 Chapter 2:Biodegradability of Cold Lake Blend and Western Canadian Select Dilbit in Freshwater........ 12 Abstract ............................................................................................................................................... 12 2.1 Introduction ................................................................................................................................... 13 2.2 Methods and Materials .................................................................................................................. 14 2.3 Results ........................................................................................................................................... 17 2.4 Discussion ..................................................................................................................................... 17 2.5 References ..................................................................................................................................... 21 Chapter 3:Comparative Study on biodegradability of Diluted Bitumen and Conventional Crude Oil ....... 33 Abstract ............................................................................................................................................... 33 3.1 Introduction ................................................................................................................................... 34 3.2 Methods and Materials .................................................................................................................. 36 3.3 Results ........................................................................................................................................... 38 3.4 Discussion ..................................................................................................................................... 42 3.5 References ..................................................................................................................................... 44 Chapter 4:Summary, Conclusion, and Future Work ................................................................................... 59 vii List of Tables Chapter 2