Northern peatlands play a significant role in the global carbon (C) cycle by functioning as sources of atmospheric methane (CH4). Peatlands are becoming polluted as a result of nitrogen (N) deposition, which is likely to impact CH4 dynamics. This thesis presents research at the Mer Bleue bog (Ottawa, Canada) in the longest known simulated atmospheric nutrient deposition experiment. After 8 years of simulated N (and other nutrient) deposition, activities of microbial communities involved in CH4 cycling have been analyzed in the laboratory and CH4 fluxes measured using chamber techniques in the field. High rates (>10 times ambient deposition) of simulated N deposition decreased CH4 production, and enhanced CH4 oxidation in vitro. However, in situ CH4¬ emissions were greater in the high N plots. I hypothesize that CH4 production is therefore driven by short-lived root exudates in the field, consistent with increased shrub biomass that occurs concomitantly with high N deposition.

The use of off-farm materials as amendments in anaerobic digestion of manure is an interesting option due to the benefits of boosting biogas production, and making the process more economical for the farmer. The addition of varying amounts of glycerol, which is a by-product of biodiesel production, was used as an amendment to anaerobic digestion of hog manure in lab-scale tests. The use of 2% glycerol produced the greatest amount of methane and biogas, however stabilization time was high, and the digestion of nutrients in the manure decreased. The addition of 4% glycerol resulted in an overloading of COD and digester failure. The addition of 1% glycerol resulted in a doubling of the methane and biogas production and the acclimation period was quite short, while the effluent quality remained good. There were no detrimental effects of using crude glycerol observed compared to using pure glcyerol. Batch tests also showed that smaller additions of glycerol (0.5%, 1%) produced the highest methane yields and were recommended as good co-substrates for anaerobic digestion with hog manure. / February 2009

The first aim of this study (Chapter III), the effects of chlorate and nitroethane on foodborne pathogens and rumen fermentation were evaluated. The experimental chlorate product, reduced (P < 0.001) fecal, but not ruminal (P > 0.05) E. coli concentrations by 1000- and 10-fold by 24 and 48 h after chlorate feeding when compared to pre-treatment concentrations (> 5.7 log10 colony forming units/g). Nitroethane treatment decreased (P < 0.01) ruminal (8.46, 7.91 and 4.74 ± 0.78 μmol/mL h-1) and fecal (3.90, 1.36 and 1.38 ± 0.50 μmol/g h-1) methane-producing activity for treatments 0, 80 and 160 mg nitroethane/kg body weight per day, respectively. Whole animal methane emissions, expressed as L/d or as a proportion of gross energy intake (%GEI) were unaffected by nitroethane treatment (P > 0.05). The second aim of this study (Chapter IV) was conducted to examine the effects of nitroethane and monensin on ruminal fermentation and nitro-metabolizing bacterial populations in vitro. The addition of nitroethane decreased methane production (μmol/mL) by at least 90%. The most probable number (MPN) of nitro-metabolizing bacterial populations was increased (P < 0.01) with the addition of nitroethane by at least 3 log10 cells/mL compared with monensin, monensin plus nitroethane or the control group. The final aim of this study (Chapter V) evaluated the effect of two sources of tannins, chestnut (CT) and mimosa (MT) on foodborne pathogens when applied as a hide-intervention and as a feed additive to feedlot cattle. Tannin spray application showed no effect of treatment or application-time (P > 0.05) on E. coli/total coliforms and total aerobes. Chestnut tannin decreased bacterial load of ruminal E. coli and total coliform by at least 0.4 log10 CFU/mL. However, fecal E. coli concentrations were increased with mimosa by 0.3 log10 CFU/g. Also, fecal total coliforms increased with the addition of chestnut or mimosa by at least 0.3 log10 CFU/g. Fecal Campylobacter concentrations (log10 CFU/g) increased with the addition of chestnut and mimosa by at least 0.4 log10 CFU/g.

A greenhouse study was conducted to investigate the mechanisms causing diurnal variations in methane emission from rice plants (Oryza sativa L.). Methane emission was measured using a closed chamber system on individual rice plants at five stages of development. The role of the rice plant as the primary methane transport component was examined by comparing emission from intact plants to plants severed above and below the water. No diurnal variations were present in the severed plants and the emission was greatly reduced when compared to the intact plant. Results from the vascular transport experiment showed that transpiration is a major factor in methane emission. Emission dependence on soil temperature was examined to test the hypothesis that soil temperature affects emission. With some plants, soil temperature was held constant using a water bath, otherwise the soil temperature was allowed to vary with environmental conditions in the greenhouse. Diurnal variations in emissions were higher for plants with uncontrolled soil temperature than for plants with controlled soil temperature. Soil temperature at a 5 cm depth explained 46% of the emission variation. Soil temperature affects the source of methane in the soil while transpiration promotes the uptake of water and subsequently the emission of methane. Methane emission was negatively correlated with biomass, probably due to effects of root biomass on soil water methane concentration. Methane concentration in soil water was negatively correlated with root biomass, most likely due to increases in soil oxidation with increasing biomass in a fixed soil volume, and change in root conductance with age.

Natural gas hydrates are solid crystalline substances found in the subsurface. Since gas hydrates are stable at low temperatures and moderate pressures, gas hydrates are found either near the surface in arctic regions or in deep water marine environments where the ambient seafloor temperature is less than 10°C. This work addresses the important issue of geomechanical stability in hydrate bearing sediments during different perturbations. I analyzed extensive data collected from the literature on the types of sediments where hydrates have been found during various offshore expeditions. To better understand the hydrate bearing sediments in offshore environments, I divided these data into different sections. The data included water depths, pore water salinity, gas compositions, geothermal gradients, and sedimentary properties such as sediment type, sediment mineralogy, and sediment physical properties. I used the database to determine the types of sediments that should be evaluated in laboratory tests at the Lawrence Berkeley National Laboratory. The TOUGH+Hydrate reservoir simulator was used to simulate the gas production behavior from hydrate bearing sediments. To address some important gas production issues from gas hydrates, I first simulated the production performance from the Messsoyakha Gas Field in Siberia. The field has been described as a free gas reservoir overlain by a gas hydrate layer and underlain by an aquifer of unknown strength. From a parametric study conducted to delineate important parameters that affect gas production at the Messoyakha, I found effective gas permeability in the hydrate layer, the location of perforations and the gas hydrate saturation to be important parameters for gas production at the Messoyakha. Second, I simulated the gas production using a hydraulic fracture in hydrate bearing sediments. The simulation results showed that the hydraulic fracture gets plugged by the formation of secondary hydrates during gas production. I used the coupled fluid flow and geomechanical model "TOUGH+Hydrate- FLAC3D" to model geomechanical performance during gas production from hydrates in an offshore hydrate deposit. I modeled geomechanical failures associated with gas production using a horizontal well and a vertical well for two different types of sediments, sand and clay. The simulation results showed that the sediment and failures can be a serious issue during the gas production from weaker sediments such as clays.

Thesis (M.S.)--West Virginia University, 2000. / Title from document title page. Document formatted into pages; contains xiii, 111 p. : ill. Includes abstract. Includes bibliographical references.

Thesis (Ph. D.)--Masssachusetts Institute of Technology and Woods Hole Oceanographic Institution, 1978. / Includes bibliographical references.

Thesis (Ph.D.)--Ohio State University, 2003. / Title from first page of PDF file. Document formatted into pages; contains xvi, 147 p.; also includes graphics (some col.). Includes abstract and vita. Advisor: Joseph A. Krzycki, Dept. of Microbiology. Includes bibliographical references (p. 122-147).

Thesis (M.S. Ch. E.)--University of South Florida, 2003. / Title from PDF of title page. Document formatted into pages; contains 70 pages. Includes bibliographical references.

In many processes it is important to have automatic control in the modern life. For example, PLC systems are using for machine control, water pressure and flow are able to be controlled by DDC program, even a car can be driven by computer. In this article, author will turn our focus on the control system for fermentation tank. The fermentation tank that produces methane is considered as clean and recycle energy source. It is widely used in house, electronic power machine and vehicle around the world. However, its reaction temperature and output concentration control are usually hard to detect without automation system. In this study, the problem is focused to combine fermentation tank and automatic control system in laboratory testing.   In this paper, author will be able to use PIC (Peripheral Interface Controller) microcontroller to solve this problem and automatically control the methane tank output methane gas with certain concentration, which could be used as energy source. The temperature and concentration sensors that are chosen as input data of the controller and corresponding algorithm were performed on the PIC. They will be used to realize the composition and thermal state measurement. With those information, the valves of material and water control can be controlled in methane tank.   Limited by the experiment equipment and methane reaction tank system, the controller was just tested in the laboratory environment instead of practical application. The test result shows that the controller has its capability to automatically control the stable output of methane gas. In the test, water and material valves are controlled automatically open or close after monitoring temperature and concentration information of the gas in the tank.