LABORATORY AND THEORETICAL INVESTIGATIONS OF DIRECT AND INDIRECT MICROBIAL INFLUENCES ON SEAFLOOR GAS HYDRATES By James Gregory Radich A Thesis Submitted to the Faculty of Mississippi State University in Partial Fulfillment of the Requirements for the degree of Master of Science in Chemical Engineering in the Dave C. Swalm School of Chemical Engineering Mississippi State, Mississippi May 2009 Copyright by James Gregory Radich 2009 LABORATORY AND THEORETICAL INVESTIGATIONS OF DIRECT AND INDIRECT MICROBIAL INFLUENCES ON SEAFLOOR GAS HYDRATES By James Gregory Radich Approved: ______________________________ ______________________________ Rudy E. Rogers W. Todd French Professor of Chemical Engineering Assistant Professor of (Director of Thesis) Chemical Engineering (Committee Member) ______________________________ ______________________________ Adrienne R. Minerick Priscilla J. Hill Assistant Professor of Associate Professor of Chemical Engineering Chemical Engineering (Committee Member) (Committee Member) ______________________________ ______________________________ Sarah A. Rajala Mark White Dean of the Bagley Chair of Chemical Engineering College of Engineering (Graduate Coordinator) Name: James Gregory Radich Date of Degree: May 2, 2009 Institution: Mississippi State University Major Field: Chemical Engineering Major Professor: Dr. Rudy E. Rogers Title of Study: LABORATORY AND THEORETICAL INVESTIGATIONS OF DIRECT AND INDIRECT MICROBIAL INFLUENCES ON SEAFLOOR GAS HYDRATES Pages in Study: 280 Candidate for Degree of Master of Science of Chemical Engineering Bacillus subtilis capable of producing surfactin was cultured to evaluate effects of microbial cell mass on natural gas hydrate formation, dissociation, and stability characteristics. The direct molecular influences of microbial cell wall polymers inhibited gas hydrate formation significantly, decreased hydrate formation rates, and increased dissociation rates. Upon the introduction of bentonite, significant synergy was observed in the system in the form of a catalytic effect. Microbes cultured from seafloor seawater-saturated sediments collected from Mississippi Canyon 118 (MC-118) produced similar effects and generalized the observed trends. MC-118 cultures also produced biosurfactant in several culture media, which was shown to catalyze natural gas hydrate formation in porous media. Microorganisms inhabit gas hydrate macrostructures and consume hydrocarbons and other substrates from within. Sulfate reduction and anaerobic hydrocarbon oxidation occurred within gas hydrate during incubations with MC-118 indigenous consortia. A mathematical model was developed to explore the diffusion-reaction implications in massive seafloor gas hydrates. DEDICATION I would like to dedicate this research and the culmination of this thesis to my daughter Piper. She is the inspiration that ultimately led me to graduate school nearly four years following my undergraduate studies. She inspires me to be all that I possibly can be, so that I may in turn inspire her in such a way someday. Also, without my unconditionally supportive and patient wife, Jenna, none of this would have been possible to begin with. ii ACKNOWLEDGEMENTS First of all I would like to acknowledge my advisor Dr. Rudy Rogers for his unwavering support in my research tangents and endeavors and for being a great mentor since I was a freshman in Mass and Energy Balances. Dr. Rogers likely spent upwards of an hour per week talking with me about my future decisions and career options during this time, and his door was never closed. He provided excellent direction for the makings of a great research project and thesis, and he has always given advice for my best interest. I would like to also acknowledge Dr. Charles Sparrow and the wisdoms he too imparted upon me as a young undergraduate student. Dr. Sparrow always said to sweat the details, and this token has many times paid for itself. Dr. Sparrow was another whose door was always open to my ponderings and ramblings and, especially, my curiosities. Dr. Hossein Toghiani is another I would like to honor for his dedication to teaching and to going completely out of his way to help students who want to learn. I do not recall learning as much from any other person that I have from Dr. H. The extended hand provided by Dr. French, both in microbiological understanding and in use of equipment, made this thesis possible. A warm thanks to Dr. French, someone whom I did not know as an undergraduate, for assisting in the advisory aspects of the project as well. Dr. French provided excellent guidance and always asked the difficult questions. iii I would also like to acknowledge Dr. Hernandez for his perspectives and mentorship since Reactor Design in 2002. When I took Reactor Design, “Rafael” was a Teaching Assistant but taught with professor-level quality. He is another who has given advice purely for my best interest. I would like to acknowledge Dr. Adrienne Minerick. She asks great questions, and her teaching style was an excellent balance of challenging the graduate students and teaching the graduate students; an often difficult balance to achieve. Dr. G. Zhang, assistant research professor, also provided great technical support within the laboratory through calibration assistance, troubleshooting, and through passing along valuable lessons learned in performing gas hydrate research in the apparatuses available. I also found a good friend along the way with Dr. Zhang. I would like to recognize the Swalm School of Chemical Engineering and all of the faculty and staff that make the department what it is. The warmth of the department is that of a family environment, and I am pleased to have had the pleasure of getting to know some of the folks who were not in the department when I previously was. Ultimately, given that my Bachelors and Masters degrees were obtained from the chemical engineering department at MSU, this thesis is a reflection of the department and the people that have made it what it is. In fact, Mr. Dave C. Swalm, a man I had the privilege of eating several dinners with as a Swalm Scholar, is greatly acknowledged for providing funding for the Dave C. Swalm School of Chemical Engineering and facilities that made research possible at this level. Lastly, I would like to acknowledge the National Oceanic and Atmospheric Administration as well as the United States Department of Energy who provided the iv grants to support this research. The grants were administered by the Mississippi Minerals Resource Institute, the Gulf of Mexico Hydrates Research Consortium, The Center for Marine Resources and Environmental Technology at the University of Mississippi, and the National Institute for Undersea Science and Technology at the University of Mississippi. I would also like to acknowledge the late Bob Woolsey of the Mississippi Minerals Resource Institute for his leadership in organizing groups of talented individuals who can contribute to a greater understanding of seafloor gas hydrate systems. v TABLE OF CONTENTS Page DEDICATION .................................................................................................................... ii ACKNOWLEDGEMENTS ............................................................................................... iii LIST OF TABLES ............................................................................................................ xii LIST OF FIGURES ......................................................................................................... xiv CHAPTER 1. INTRODUCTION ....................................................................................................1 1.1 Gas Hydrate Definition and History ....................................................................1 1.2 Gas Hydrate Significance and Occurrence ..........................................................3 1.3 Applications of Gas Hydrates ..............................................................................6 1.3.1 Natural Gas Storage and Transport ............................................................6 1.3.2 Desalination ................................................................................................7 1.3.3 Gas Separation ............................................................................................7 1.3.4 Carbon Dioxide Sequestration ....................................................................8 1.4 Research Objective ..............................................................................................8 2. LITERATURE SURVEY .......................................................................................11 2.1 Seafloor Gas Hydrates .......................................................................................11 2.1.1 Microorganisms Associated with Seafloor Gas Hydrates ........................13 2.1.2 Indirect Microbial Influences on Seafloor Gas Hydrates .........................14 2.1.2.1 Biosurfactants ............................................................................15 2.1.2.2 Metal Oxidation-Reduction .......................................................17 2.1.2.3 Sediment-Microbe and Sediment-Biosurfactant Adsorption ....18 2.1.3 Direct Microbial Influences on Seafloor Gas Hydrates ...........................21 2.1.3.1 Sulfate-Reduction and Anaerobic Hydrocarbon Oxidation ......22 2.1.3.2 Methanogenesis .........................................................................23 2.1.4 Gas Hydrate Stability Zone ......................................................................24