No description available.

No description available.

The research objectives for this study involved the development of a modified thermophilic fluidized bacterial granular bed bioreactor system for the production of biohydrogen from sucrose. The granules were comprised of an undefined anaerobic thermophilic multispecies consortium of bacteria. In order to establish the thermophilic bacterial granules, the bioreactor was operated as a chemostat under increasing dilution rates. This promoted the selection and enrichment of thermophilic granules comprised of a multispecies bacterial consortium. Endo medium which is one of the most basic bacteriological nutrient mediums was used as the nutrient supply in the granule generating chemostat experiments. Bacterial inoculums from mesophilic environments were used to induce and establish thermophilic and extreme-thermophilic adapted bacterial granules in the chemostat experiments. Granulation was successfully induced under a thermophilic temperatures ranging from 55 oC to 70 oC within a period ranging from 5 to 14 days. Bioreactor design and operation was modified so as to increase both hydrogen yield (HY) and volumetric hydrogen productivity (HP). It was found that in order to increase both HY and HP it was necessary to implement a number of modifications in bioreactor design and operation. The two key operational parameters were temperature and de-gassed effluent recycling rate through the bioreactor bed. Through the incorporation of a solid-liquid separator in the form of 11.6 L settling column, bacteria granular bed wash out was prevented for a 5.0 L thermophilic bioreactor system operated at high volumetric biomass densities, low hydraulic retention times and high degassed effluent recycle rates. Stability of the bioreactor operation in terms of volumetric hydrogen productivity (L H2/L/h), %H2 content and pH maintenance was readily maintained for 50 days. While volumetric hydrogen productivity increased with bacterial biomass density, both hydrogen yield (mol H2/mol glucose) and specific hydrogen productivity (L H2/g/h) declined with increasing biomass density. In this process the rate of physical removal of H2 trapped in the bulk liquid phase surrounding the fluidized granules reduced the thermodynamic constraints preventing the simultaneous achievement of high HPs and high HYs in a granular fluidized bed derived from an undefined bacterial culture. It became evident that a thermophilic temperature alone was an insufficient condition to achieve simultaneously high HPs and high HYs. It also became evident that hydraulic retention time for degassed effluent recycling was a critical for the simultaneous achievement of high HPs and high HY. It was discovered that a reduction in the total volume of bioreactor system relative to increasing rates of degassed effluent recycle was a necessary condition for the simultaneous achievement of both high HPs and high HYs. Thus at thermophilic temperatures any increase in the bioreactor system volume should also be accompanied by a concomitant increase in the rate of degassed effluent recycling so the HRT always remained below the critical threshold necessary for the simultaneous achievement of high HPs and high HYs. Once it was demonstrated that by the adjusting bioreactor system volume and the degassed to effluent recycle rates both high HPs and high HYs could be achieved only under thermophilic conditions it was necessary to show that under these operational condition the system would produce net positive work in terms of hydrogen energy production. It was shown through modeling heat exchanges that if the bioreactor was effectively insulated and waste heat was recycled or recovered then net positive work was accomplished by the bioreactor system. Bacterial granules grown from mesophilic inoculant were adapted to generate H2 from sucrose under a range of thermophilic temperatures (55, 60, 65, 70 oC). Attainments of two H2 generation process goals were assessed. First, whether a net positive net energy balance at thermophilic temperatures and high effluent recycle rates were attainable. Secondly, whether the volumetric hydrogen productivities were sufficient to drive a 5 kW fuel cell when scale-up to 1 m3

No description available.

Nitrogen removal from wastewater is important for the revention of significant health and environmental impacts such as eutrophication. Nitrogen removal is achieved by the combined action of nitrification and denitrification. Nitrification is performed by autotrophic, slow growing microorganisms that require oxygen and are inhibited in the presence of denitrifiers when oxygen and COD are available due to competition for oxygen. Denitrification however, performed by relatively fast growing heterotrophic bacteria, is inhibited by oxygen and requires COD. This implies that nitrification and denitrification are mutually exclusive. The supply of oxygen to a fresh wastewater, high in ammonia and COD, causes waste of both oxygen and COD. Conservation of COD is therefore critical to efficient wastewater treatment. The approach investigated in this study to achieve complete nitrogen removal was to physically separate the nitrification and denitrification biomasses into separate bioreactors, supplying each with appropriate conditions for growth and activity. A storage driven denitrification sequencing batch biofilm reactor (SDDR) was established which exhibited a high level of COD storage (up to 80% of influent COD) as poly-B-hydroxybutyrate capable of removing >99% of nitrogen from wastewaters with a C/N ratio of 4.7 kg COD/kg N–NO3 –. The SDDR was combined in sequential operation with a nitrification reactor to achieve complete nitrogen removal. The multiple stage, multiple biomass reactor was operated in sequence, with Phase 1 - COD storage in the storage driven denitrification biofilm; Phase 2 - ammonia oxidation in the nitrification reactor; and Phase 3 - nitrate reduction using the stored COD in the storage driven denitrification reactor. The overall rate of nitrogen removal observed was up to 1.1 mmole NH3 L–1 h–1 and >99% of nitrogen could be removed from wastewaters with a low C/N ratio of 3.9 kg COD/kg N–NH3. The multiple stage, multiple biomass system was limited in overall nitrogen removal the reduction in pH caused by nitrification. A parallel nitrification-denitrificatio (PND) reactor was developed in response to the pH control issue. The PND reactor was operated with Phase 1 – COD storage in the storage driven denitrification biofilm and Phase 2 – simultaneous circulation of reactor liquor between the denitrification and nitrification biofilms to achieve complete nitrogen removal and transfer of protons. The PND reactor performed competitively with the multistage reactor (removal of >99% nitrogen from wastewaters with feed ratios of 3.4 kg COD/kg N–NH3) without the need for addition of buffering material to oderate the pH.

The primary purpose of this study was to (1) develop methods for the analysis of and (2) provide information on the chemical nature of reducing ends in typical cellulose substrates used for the study of cellulolytic enzymes. The studies were designed such that values obtained for cellulose substrates were compared with those obtained for a series of soluble cellooligosaccharides. The initial phase of the study tested the validity of using established colorimetric reducing sugar assays, developed for the measurement of reducing sugars in solution, for the quantification of reducing ends on insoluble substrates. The results demonstrate that published methods give widely differing values for the number of reducing ends per unit weight cellulose. The Cu⁺⁺-based assay, using bicinchoninic acid (BCA) as a color yielding chelator of Cu⁺, is shown to provide values that appear most consistent the properties of the substrates. A method was developed using the Cu⁺⁺-BCA reagent, following a mild sodium borohydride treatment, to provide an estimate of the number of solvent accessible reducing ends on insoluble substrates. The kinetics of sodium borohydride reduction of reducing ends on crystalline cellulose, amorphous cellulose and soluble cellooligosaccharides were compared in order to ascertain the relative reactivity of these reducing ends. The apparent second order rate constants for the reduction of reducing ends associated with the crystalline celluloses were significantly lower than those for the reduction of reducing ends associated with either the insoluble amorphous celluloses or the soluble cellooligosaccharides. These results indicate the reducing ends associated with crystalline celluloses are not extended out from the surface as though mimicking solution phase reducing ends. The relevance of this, as well as the other results, to the behavior of cellulolytic enzymes is discussed. The final phase of the study was the demonstration of both a reducing sugar-based and a viscositybased assay for the detection of a prototypical polysaccharide depolymerizing glycosyl hydrolase, polygalacturonase. / Graduation date: 2004

Thesis (M.S.)--Oregon State University, 2007. / Printout. Includes bibliographical references (leaves 111-114). Also available on the World Wide Web.

In order to produce ethanol derived from lignocellulosic feeds at a cost that is competitive with current gasoline prices, the fermentation process, converting sugars to produce ethanol and the subsequent purification steps, must be enhanced. Due to their comparatively lower costs, the widespread availability across a range of climates, and their status as a dedicated energy crop, lignocellulosic biomass feeds are ideal raw materials that can be used to produce domestic fuels to partly displace our dependence on non-renewable sources. Currently, a major drawback of the technology is the relatively low ethanol tolerance of the micro-organisms used to ferment xylose and glucose. To alleviate the ethanol inhibition of Escherichia coli KO11 (ATCC 55124) during fermentation, online ethanol sequestration was achieved through the implementation of an externally located packed bed adsorber for the purpose of on-line ethanol removal (using F-600 activated carbon). By removing ethanol from the broth during the fermentation, inhibition due to the presence of ethanol could be alleviated, enhancing the substrate utilization and fermentation rate and the ethanol production of the fermentation. This study details a comprehensive adsorbent screening to identify ethanol selective materials, modelling of multi-component adsorption systems, and the design, implementation and modelling of a fermentation unit coupled with an externally located packed bed adsorber.

Biofuels like ethanol are gaining serious momentum because of concerns over climate change and the rising cost of fossil fuels. Saskatchewan is the first province in Canada to pass a law requiring ethanol blended into its gasoline. A blend rate of 7.5% is mandated as of January 2007. This legislation is not yet fully enforced as ethanol production cannot currently meet demand, but local production is increasing. The traditional method of production is via grain fermentation; however the food versus fuel debate indicates this is unethical when food shortages and prices are already on the rise. Gasification is a robust technology for processing raw, non-food grade biomass into syngas (H2 and CO) which can then be further converted to ethanol via gas-to-liquid conversion technology. Condensable materials called tars form during gasification and must be further converted to gaseous products to avoid problems downstream. This can be achieved via optimization of process conditions and catalysis. The research for this thesis was carried out in two phases. Phase 1 examined the effects of process conditions on the noncatalytic temperature-programmed gasification of wood (Jack Pine) biomass. Temperature was varied from 700 to 825oC, water flow rate was varied from 2 to 5 cm3/h, and N2 flow rate from 16 to 32 cm3/min. When varying biomass gasification conditions, overall % carbon conversion to gaseous products reached a maximum of 70% at 825oC, 5.0 cm3/h H2O, and 32 cm3/min N2. 670 cm3 product gas per g biomass was produced, with 35.8 mol% H2 and H2:CO of 1.56. In Phase 2, catalytic gasification of wood biomass was carried out using a double bed micro reactor in a two-stage process. Temperature programmed steam gasification of biomass was performed in the first bed at 200-850oC. Following in the second bed was isothermal catalytic decomposition gasification of volatile compounds (including tars). Dolomites from Canada, Australia and Japan were examined for their effects on tar abatement and the overall gaseous product. The gasification of pine sawdust resulted in 74% of carbon emitted as volatile matter during tar gasification (200-500oC biomass bed temperature). High temperature, high H2O flow rate and low carrier gas flow rate are recommended for improving biomass conversion to gaseous products. Dolomites improved tar decomposition by an average 21% at 750oC isothermal catalyst bed temperature. For Canadian dolomites, iron content was found to promote tar conversion and the water-gas shift reaction, but the effectiveness reached a plateau at 1.0 wt% Fe present in dolomite. The best dolomite was Canada # 1, from an area west of Flin Flon, Manitoba. This dolomite yielded 66% tar conversion (25% above noncatalytic results) at 750oC using 1.6 cm3 catalyst/g biomass. Carbon conversion increased to 97% using 3.2 cm3 catalyst/g biomass at the same temperature. The dolomite seemed stable after 15 hours of cyclic use at 800oC.

In order to produce ethanol derived from lignocellulosic feeds at a cost that is competitive with current gasoline prices, the fermentation process, converting sugars to produce ethanol and the subsequent purification steps, must be enhanced. Due to their comparatively lower costs, the widespread availability across a range of climates, and their status as a dedicated energy crop, lignocellulosic biomass feeds are ideal raw materials that can be used to produce domestic fuels to partly displace our dependence on non-renewable sources. Currently, a major drawback of the technology is the relatively low ethanol tolerance of the micro-organisms used to ferment xylose and glucose. To alleviate the ethanol inhibition of Escherichia coli KO11 (ATCC 55124) during fermentation, online ethanol sequestration was achieved through the implementation of an externally located packed bed adsorber for the purpose of on-line ethanol removal (using F-600 activated carbon). By removing ethanol from the broth during the fermentation, inhibition due to the presence of ethanol could be alleviated, enhancing the substrate utilization and fermentation rate and the ethanol production of the fermentation. This study details a comprehensive adsorbent screening to identify ethanol selective materials, modelling of multi-component adsorption systems, and the design, implementation and modelling of a fermentation unit coupled with an externally located packed bed adsorber.