Theses and Dissertations at Montana State University (MSU)
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Item Biofuel potential, nitrogen utilization, and growth rates of two green algae isolated from a wastewater treatment facility(Montana State University - Bozeman, College of Engineering, 2011) Eustance, Everett O'Brien; Chairperson, Graduate Committee: Brent M. Peyton; Robin Gerlach (co-chair)Nitrogen removal from wastewater by algae provides the additional benefit of producing lipids for biofuel and biomass for anaerobic digestion. As ammonium is the renewable form of nitrogen produced during anaerobic digestion and one of the main nitrogen sources associated with wastewater, experiments focused on the optimization of growth and lipid production when grown on ammonium were evaluated. Scenedesmus sp. 131 and Kirchneriella sp. 92 were grown in a 14:10 light/dark cycle on ammonium, nitrate or urea in the presence of 5% CO 2 and ammonium and nitrate in the presence of air. Growth on nitrate and urea showed similar growth rates, and provided knowledge on the target growth rate for optimizing growth on ammonium. Results showed the pH decreased during exponential growth on ammonium in both 5% CO 2 and air, causing chlorophyll degradation. Growth on nitrate and air increased the pH of the medium and produced an increase in Nile Red fluorescence and biofuel potential for strain 131, but not for strain 92. Biological buffers were implemented to counteract the change in pH to prevent growth inhibition. Cultures were grown on 5% CO 2 or air, which showed that increased levels of CO 2 are required for increased growth, biofuel potential, and ammonium utilization. This increased the growth rates from 0.26 d -¹ to 1.04 d -¹ for strain 131 and 0.45 d -¹ to 1.31 d -¹ for strain 92. pH-controllers using 0.1 M KOH were used in experiments with 5% CO 2 with the understanding that buffers are limited to lab scale experiments and pH control would bridge the gap to industrial processes. The growth rate while utilizing pH-controllers showed similar growth rates to buffered experiments. Growth on nitrate, urea, and buffered ammonium with 5% CO 2 showed an increase in the biofuel potential for strain 92 in comparison to growth with air. Strain 131 had a decrease in biofuel potential when grown on ammonium compared to growth on nitrate or urea. Both strains showed increased levels of CO 2 is required to increase biofuel productivity.Item Microbial conversion of biodiesel by-products to biofuel(Montana State University - Bozeman, College of Letters & Science, 2010) O'Shea, Kelly Frances; Chairperson, Graduate Committee: Matthew FieldsBiodiesel is an alternative liquid transportation fuel derived from biological oils. It is a renewable form of transportation fuel that can be easily integrated into society's current infrastructure. Biodiesel is cleaner burning than petroleum, emitting less carbon pollution and harmful toxins (i.e. sulfur, benzene). One of the major by-products from biodiesel production is crude glycerin. With the increased production of biodiesel, glycerin production will continue to increase. Glycerin was once considered a valuable co-product but now is considered a low-value by-product. In the following study, different co/tricultures of sulfate reducing bacteria (SRB) and methanogens were grown with crude glycerin as a means to convert the waste product into a renewable energy source, methane. The SRBs, Desulfovibrio vietnamensis and Desulfovibrio alcoholovorans 6133, were grown syntrophically, in different co/triculture combinations, with Methanococcus maripaludis, Methanoculleus marisnigri, and Methanosarcina acetivorans. Co/tricultures were investigated for the ability to produce methane via the utilization of pure glycerol, fractionated glycerin, and crude glycerin as carbon and energy sources. In order to gain insight into cellular physiology, glycerol, acetate, free fatty acid, and methane concentrations were measured throughout growth. The co/tricultures grew fastest on pure glycerol and experienced a lag phase in growth on fractionated glycerin and longer lag phases when transferred to crude glycerin. However, methane yields were similar on all three carbon sources. Methane production depended on the carbon source and culture composition. Co/tricultures growing on pure glycerol and fractionated glycerin displayed a decrease of methane production as growth rate increased. The opposite was seen with growth on crude glycerin. With most cultures, the addition of M. acetivorans increased methane concentrations significantly. M. acetivorans displayed the capability of utilizing the by-product, acetate, from SRB oxidation of glycerol and the methanol layer from fractionated and crude glycerin. M. acetivorans appeared to interfere with the coculturing of D. vietnamensis and M. marisnigri based on decreased methane production. Cocultures with M. maripaludis grew poorly and produced little methane when grown on the supernatant of M. acetivorans. This is the first study to characterize the utilization of crude glycerin from biodiesel production by syntrophic cultures of SRB and methanogenic archaea.Item The invasion potential and competitive ability of Camelina sativa (L.) Crantz (camelina) in rangeland ecosystems(Montana State University - Bozeman, College of Agriculture, 2010) Davis, Philip Browning; Chairperson, Graduate Committee: Fabian D. Menalled.Camelina sativa (L.) Crantz (large-seeded false-flax) is a recently introduced oilseed crop in Montana and has potential for large scale production for the biofuel market. However, due to weedy characteristics, the invasive potential of this species is of concern. A need exists to create a pre-entry protocol to accurately assess risk to minimize uncertainty inherent in qualitative weed risk assessment approaches. We assessed the probability of C. sativa to invade rangeland ecosystems of southwest Montana to address this concern. The objectives of this study were to 1) quantitatively assess the invasion potential of C. sativa by collecting demographic data over two years and developing a population dynamics model, 2) compare experimental results and modeling outcomes to predictions suggested by a qualitative weed risk assessment system, and 3) assess the impact of growing conditions on the relative competitiveness of C. sativa and Brassica napus (L.) (canola). Objective 1 was carried out in two contrasting rangeland ecosystems to assess the effects of disturbance and seeding season on emergence, survival, and fecundity rates of C. sativa. Population growth (lambda) was forecasted by developing a population dynamics model. Resulting lambda values from simulations using observed data never exceeded 0.03 and the maximum time to extinction was six years. The low lambda values indicate that the threat of invasion by this species in the studied ecosystems is low. Objective 2 compared quantitative results to predictions from the Australian weed risk assessment (WRA) model. In contrast to experimental results, outcomes from the WRA suggested that this species should not be allowed entry into the region. These opposing results highlight the need for a more comprehensive approach to weed risk assessment. Objective 3 was conducted over three trials in two greenhouses. A replacement series design was used to estimate the effects of soil conditions and the presence of an invasive weed, Bromus tectorum (L.) (cheatgrass, downy brome), on the competitive outcomes between C. sativa and canola. Replacement series diagrams determined that competition occurred and that canola was the superior competitor in all treatments, thus providing further evidence that the invasion potential of C. sativa is low.