Synthesis of bioethanol from lignocellulosic materials: A focus on grass and waste paper as raw materials
- Authors: Vala, Mavula Kikwe
- Date: 2009-12
- Subjects: Ethanol as fuel , Biomass energy , Lignocellulose -- Biotechnology
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10353/24499 , vital:63049
- Description: Biofuels are currently recognized as not only a necessity, but an inevitable pathway to secure the planet future energy needs. Food crops have been used (so far) as the biomass for bioethanol and biodiesel production. This has increased concerns over food security and led to the search for diversification and alternative feedstocks for biofuel production. The use of lignocellulosic materials, the most abundant, low cost and easy feedstock to harvest for bioethanol purpose, involves challenging production processes. Several approaches have been used to facilitate the breakdown of the biopolymer structure to produce fermentable sugars that can be converted to ethanol. Most of the approaches have used high temperatures and pressures and have often led to the production of inhibitors of fermentation. In this study, lignocellulosic materials from grass and newsprint were investigated as sources of biomass for bioethanol production using a chemical route (sulfuric acid hydrolysis) which made use of temperatures below 100°C at normal atmospheric pressure. Fermentation of toxic lignocellulosic hydrolyzates was possible after the development of a method for inhibitors removal. The method used treated wood chips as a stationary phase in a chromatographic column to remove inhibitors. This method is expected to be extended to applications such as in municipal wastewater treatment. Sugar yields of 22.26 and 8.9 g/L of hydrolyzate; and an ethanol yield of 184.5 and 130.4 mg/mL of must were achieved for 5g grass and newsprint respectively using optimum conditions of 2percent H2SO4 at 97.5°C for grass and 0.5percent H2SO4 at 97.5°C for newsprint during the hydrolysis process. Pure cellulose was used as a control for the biomass where 254.1 g/L of fermentable sugars were recovered from soluble cellulose and the yield of ethanol was 201.8 mg/mL. , Thesis (MSc) -- Faculty of Science and Agriculture, 2009
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- Date Issued: 2009-12
The quantification of Pinus patula recovery and productivity of manually orientated biomass collection in post mechanised full tree and semi mechanised tree length harvesting operations
- Authors: Ncongwane, Thandekile Hazel
- Date: 2023-04
- Subjects: Pinus patula – south Africa , Forest ecology , Biomass energy
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10948/61511 , vital:70692
- Description: The use of biomass as an alternate source of energy has grown in popularity. Different types of biomass are obtained from a variety of sources including natural forests, forestry plantations and agriculture residues. However, forestry residues have been identified as the most promising source, due to the wide variety of plant products including leaves, twigs, branches, merchantable stem, stumps and roots. The main sources of plantation forest biomass are residues from thinning, clearfell and conventional products such as pulpwood and sawn timber operations. These residues can accumulate between 4.3 to 9.4 billion tonnes annually around the world. The biomass availability in plantation forests has led to the development of different harvesting systems to help collect the products from infield to sawmill. Biomass harvesting has mainly been achieved through mechanised systems because of their high yields. However, the use of manual systems has been neglected due to technical limitations and financial viability. Thus, in South Africa, there is no scientific research looking at manual systems of collecting biomass from plantations. Because of this, different forestry stakeholders, including small growers and contractors using manual systems for biomass harvesting have limited knowledge regarding what to expect in terms of recoverable amounts, productivity and cost. This research examines the productivity of the manual biomass collection and the quantification of recovered and unrecovered residues after mechanised full tree (FT) and semi mechanised tree length (TL) harvesting operations in Pinus patula compartments. A total number of 8 plots with +/-200 standing trees were marked in each system. The diameter and height of all marked trees were measured to determine tree volume. Moreover, the quantification of recoverable woody biomass was determined, where after, a residues assessment method using plots and line transects was used to determine the amount of unrecovered residues. , Thesis (MSc) -- Faculty of Science, School of Environmental Sciences, 2023
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- Date Issued: 2023-04
Evaluation of cellulase and xylanase production by two actinobacteria species belonging to the Micrococcus genus isolated from decaying lignocellulosic biomass
- Authors: Mmango-Kaseke, Ziyanda https://orcid.org/0000-0002-8936-1149
- Date: 2016-05
- Subjects: Lignocellulose , Biomass energy
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10353/24197 , vital:62442
- Description: Bacteria were isolated from sawdust and screened for cellulase and xylanase production on carboxyl methyl cellulose (CMC) and birchwood xylan agar. The bacteria showing halo forms around the colony were selected for further analyses and those isolates with the highest cumulative halozone size (isolate PLY1 and MLY10) were chosen for detailed studies. Evaluation of cellulase and xylanase production by saw dust actinobacterial species whose 16S rDNA nucleotide sequences were deposited in GenBank as Micrococcus luteus strain SAMRC-UFH3 with accession number KU171371 and Micrococcus yunnanensis strain SAMRC-UFH4 with accession number KU171372. Optimum culture conditions for the production of cellulase for respective axenic culture include incubation period (96 h), incubation temperature (25oC), agitation speed (50 rpm), and pH 5. For xylanase production, the optimum culture conditions in the presence of 1percent (w/v) birchwood xylan include incubation period (84 h), incubation temperature (25oC), agitation speed (200 rpm), and pH 10. For Micrococcus yunnanensis strain SAMRC-UFH4 cellulase production was optimal under such conditions as, incubation temperature (30oC), agitation speed (0 rpm), and pH 5, while xylanase production was optimal at, incubation temperature (30oC), agitation speed (150 rpm), and pH 10. The high cellulase and xylanase activity obtained from these isolates suggest suitability of the organisms as important candidates for commercial application. , Thesis (MSc) -- Faculty of Science and Agriculture, 2016
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- Date Issued: 2016-05
Investigation of brewery waste grains and microbial fuel cells as value-additive technologies improving solvent production yields in Clostridium acetobutylicum (ATCC 824) fermentation
- Authors: Du Toit, Ryan Guillaume
- Date: 2023-10-13
- Subjects: Biomass energy , Butanol , Fermentation , Microbial fuel cells , Brewery waste , Clostridium acetobutylicum
- Language: English
- Type: Academic theses , Master's theses , text
- Identifier: http://hdl.handle.net/10962/424643 , vital:72171
- Description: The production of the solvent compounds acetone, ethanol and butanol through fermentation of organic feedstocks using Clostridia species could be a promising route for biofuel production. However, the cost of raw materials, low yields and the complexity of anaerobic fermentation continue to hinder this means of generating these compounds. The research presented in this Thesis investigated low-cost interventions that could decrease the costs of production and to direct the synthesis of fuel compounds using microbial fuel cells. Low-cost anaerobic chambers were designed and constructed for the propagation and manipulation of Clostridium acetobutylicum, selected as a low-risk microbial catalyst. Fermentation was monitored using in situ pH measurements and a combination of turbidity measurements, nutrient assays (especially total carbohydrates) and HPLC-RI detection as a means of monitoring the consumption of nutrients (glucose), production of precursor compounds (butyric acid) and the formation of solvent molecules (acetone/ethanol and butanol) during fermentation by this organism. Brewer’s spent grains were tested as a sustainable and low-cost feedstock for solvent production, comparing the effects of sterilising before fermentation, or allowing resident microflora to remain during Clostridium-catalysed solvent production. Sterilised spent grains significantly improved the production of solvent molecules (e.g. 12.97 ± 0.38 g/L of butanol yielded, compared to 0.40 ± 0.33 g/L for defined media sampled during the solventogenic phase); compared to these, the use of non-sterilised brewer’s grain decreased both the reproducibility and yields of fermentation (8.66 ± 1.6 g/L of butanol). Microbial fuel cells were studied as a possible means of altering electron transfer to/from electrode-attached Clostridia to control the metabolic shift in bacteria from acidogenesis to solventogenesis. The base line MFC (11.00 ± 4.69 g/L) fermentation experiment did produce higher acetone/ethanol than the baseline batch experiment MB (5.47 ± 4.48 g/L), indicating an improvement to solvent production in C. acetobutylicum (ATCC 824) in a MFC fermentation. In this study, MFC-1 demonstrated remarkable superiority over MB in terms of butyric acid production, yielding significantly higher concentrations while also improving acetone and ethanol production. However, the enhanced butyric acid production did not correspond to significantly increased butanol yields when compared to batch fermentation of chemically defined media. These findings highlight the potential of MFC-1 as an efficient approach for enhancing the fermentative production of valuable compounds, with a particular focus on butyric acid and acetone/ethanol. , Thesis (MSc) -- Faculty of Science, Biotechnology Innovation Centre, 2023
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- Date Issued: 2023-10-13