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

The objective of this study was to evaluate the short-term (one-year) biomass production in red clover and to obtain an estimate of the heritability of this characteristic. Progenies from parents with high biomass had higher biomass than those from parents with low biomass or having one parent in each category. The narrow-sense heritability estimated from mid-parent offspring regression was 0.23, from parent-offspring correlation was 0.22, and realized heritability was 0.15, indicating that progeny testing would be required for successful selection of populations with greater biomass production. Plants selected for high biomass production tended to have higher shoot:root ratios and flower more profusely than the parental checks and the low biomass plants. This indicates that by selecting for high biomass, red clover will be selected for more annual growth habit at the same time.

No description available.

A dissertation submitted to the Faculty of Science, University of the Witwatersrand, Johannesburg, in fulfilment of requirements for the degree of Master of Science. 2014. / Sugar cane bagasse and switch grass were used to investigate their potential in the remediation (decreasing metal ion concentration and increasing pH) of Acid Mine Drainage (AMD) and the possibility that the AMD residue sludge containing cellulose could be further hydrolysed using a commercial cellulase enzyme system to produce glucose for bioprocesses. In general both the feedstocks series appeared to increase pH and reduce dissolved iron concentration after being incubated with AMD for a period of 14 weeks at room temperature. The milled switch grass was shown to have a greater remediating effect on AMD, raising the pH from 2.11 to 5.46, and decreasing iron concentration from 500mg/l to 174mg/l, a decrease of 62%. The sugar cane bagasse was shown to have the least remedial effect, increasing pH from 2.11 to 2.38, and only reducing iron concentration by 30%. The 2‐5cm switch grass raised the pH from 2.11 to 3.86, and the iron concentration was reduced from 500mg/l to 283mg/l, a 42% reduction. The milled grass series was chosen for further enzymatic hydrolysis. The milling reduced the size of the switch grass and destroyed the cell structure making it more accessible to AMD treatment. This also allowed the enzyme in the hydrolysis to penetrate to the fibres and reach the sugar oligomers. The sludge of the AMD treated switch grass was incubated with cellulases enzymes for 24 hours at 50oC, producing glucose concentration of up to 4,86mg/ml.

The thesis presents a thorough, in-depth study that fills some of the gaps in the knowledge of the impacts of woodland utilisation in communal areas. The chosen case study villages are in Bushbuckridge, a government gazetted Integrated Sustainable Rural Development programme node, making the results pertinent to sustainable energy policy reform in South Africa. A case-study of two villages was used to investigate the spatial and structural changes in fuelwood supply in response to fuelwood extraction as well as the changes in use-patterns over time. A survey of the structure and composition of the woody vegetation and wood harvesting patterns around the villages was conducted and compared against historical data, spanning 17 years. Total wood stock in the communal woodlands of both villages declined over the study period; the loss being greater in Welverdiend. Significant, negative change in the structure and species composition, particularly of species that are commonly harvested for fuelwood has occurred in Welverdiend but not in Athol. The absence of negative impacts in Athol implies that harvesting regimes here are more sustainable but it is more likely that this is due to the lower human population and lower fuelwood extraction pressure. The changes in woodland structure were linked to landcover change patterns that occurred in the villages over the last 44 years, from their creation through forced resettlements on old farms in the area. Landcover change patterns were similar in both villages since 1965 but there was significantly greater woodland loss in Welverdiend (48% woodland loss) in comparison to Athol (25% woodland loss). The systematic loss of woodland areas to agricultural fields was linked to expanding residential areas due to human population growth. Deforestation occurred where woodlands were already impacted through selective harvesting. The physical changes in woodland structure and landcover were linked to a detailed socio-economic analysis of the two villages, providing critically important data for the sustainable management of woodlands in South Africa. The impact of access to electricity on fuelwood consumption rates was carried out through analysis of the economic, time and opportunity costs of fuelwood collection, compared against the different fuelwood availability in each village. In Welverdiend demand for fuelwood has so far proved inelastic; households have adjusted their fuelwood collection regimes, going on fewer collection trips but spending longer times for each trip but ultimately household investment is similar to that in Athol. Fuelwood demand is maintained in Welverdiend by the availability of purchased fuelwood and harvesting in new sites. A model to predict the socio-economic factors at the household and per capita level which affect fuelwood consumption was developed. Revealing in the process that households with access to electricity used less fuelwood annually and the amounts of fuelwood used were influenced by the household perceptions of fuelwood scarcity in the village, Household population size had a direct bearing on the likelihood of households switching to electricity with every addition to the household size decreasing the likelihood of switching by 48%. This study has major implications for the government’s on-going rural electrification programme. Interventions are required that raise awareness about fuelwood availability trends, based on landscape developments and targeting women as the main users of fuelwood.

Thesis (M.S.)--Northern Michigan University, 2007. / Bibliography: leaves 44-48.

Thesis (Ph. D.)--Oregon State University, 2003. / Typescript (photocopy). Includes bibliographical references (leaves 133-142). Also available on the World Wide Web.

Thesis (M.S.)--Oregon State University, 2009. / Printout. Includes bibliographical references (leaves 37-41). Also available on the World Wide Web.

Thesis (M.S.)--Oregon State University, 2005. / Printout. Includes bibliographical references. Also available on the World Wide Web.

Thesis (M.S.)--University of New South Wales, 1999. / Title from PDF title page (viewed on May 2, 2005). Includes bibliographical references (p. [134]-154).