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Solid-state fermentation of whole sugarcane and paper sludge for first- and second-generation ethanol production
van Dyk, J. 2025. Solid-state fermentation of whole sugarcane and paper sludge for first- and second-generation ethanol production. Unpublished doctoral dissertation. Stellenbosch: Stellenbosch University [online]. Available: https://scholar.sun.ac.za/items/3c69ae21-8b00-4b43-b0de-b26fca40aa75
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| Format: | Thesis |
| Language: | English |
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Stellenbosch : Stellenbosch University
2025
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| _version_ | 1867613831052656640 |
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| access_status_str | Open Access |
| author | Van Dyk, Janke |
| author2 | Van Rensburg, Eugene |
| author_browse | Van Dyk, Janke Van Rensburg, Eugene |
| author_facet | Van Rensburg, Eugene Van Dyk, Janke |
| author_sort | Van Dyk, Janke |
| collection | Thesis |
| dc_rights_str_mv | Stellenbosch University |
| description | van Dyk, J. 2025. Solid-state fermentation of whole sugarcane and paper sludge for first- and second-generation ethanol production. Unpublished doctoral dissertation. Stellenbosch: Stellenbosch University [online]. Available: https://scholar.sun.ac.za/items/3c69ae21-8b00-4b43-b0de-b26fca40aa75 |
| format | Thesis |
| id | oai:scholar.sun.ac.za:10019.1/132347 |
| institution | Stellenbosch University (South Africa) |
| language | English |
| last_indexed | 2026-06-10T12:42:21.587Z |
| license_str | Other — see source repository |
| provenance_str_mv | Harvested via OAI-PMH from SUNScholar — Stellenbosch University Repository |
| publishDate | 2025 |
| publishDateRange | 2025 |
| publishDateSort | 2025 |
| publisher | Stellenbosch : Stellenbosch University |
| publisherStr | Stellenbosch : Stellenbosch University |
| record_format | dspace |
| source_str | SUNScholar — Stellenbosch University Repository |
| spelling | oai:scholar.sun.ac.za:10019.1/132347 Solid-state fermentation of whole sugarcane and paper sludge for first- and second-generation ethanol production Van Dyk, Janke Van Rensburg, Eugene Gorgens, Johann Ferdinand Stellenbosch University. Faculty of Engineering. Dept. of Chemical Engineering. Solid-state fermentation Sugarcane -- Biotechnology Biomass conversion Lignocellulose -- Biotechnology Lignocellulose -- Biotechnology UCTD van Dyk, J. 2025. Solid-state fermentation of whole sugarcane and paper sludge for first- and second-generation ethanol production. Unpublished doctoral dissertation. Stellenbosch: Stellenbosch University [online]. Available: https://scholar.sun.ac.za/items/3c69ae21-8b00-4b43-b0de-b26fca40aa75 Thesis (PhD)--Stellenbosch University, 2025. ENGLISH ABSTRACT: The conversion of biomass to first (1G)- or second-generation (2G) bioethanol typically occurs under conditions of submerged fermentation. Solid-state fermentation (SStF), wherein the substrate typically contains low quantities of free water, is an attractive alternative, due to smaller reactor volumes, higher final product concentrations, and a reduction in liquid waste requiring treatment. Paper sludge (PS) and whole sugarcane are two substrates that are potentially suitable for solid-state fermentation. Millions of tonnes of high-moisture (>70%) PS are sent to landfills, which results in large water volumes that are discharged with the waste stream in an uncontrolled manner, contributing significantly to greenhouse gas emissions and pollution. Valorising this organic waste to bioenergy will advance a circular bio-economy wherein waste is minimised, and valuable products are sustainably produced. Conventional methods of bioethanol production from sugarcane involve energy-intensive steps to extract and concentrate the sucrose-rich juice. Alternatively, SStF using milled cane can simplify the processing method and thereby reduce its energy consumption. Whole cane fermentation may potentially find application in small-scale distilleries due to the simplified processing equipment and methods. There is a paucity of published reports on the production of ethanol from PS and sugarcane under solid-state conditions, although examples of solid-state conversion of sweet sorghum stems into ethanol have been reported. This study assessed the SStF of PS and whole sugarcane in lab-scale horizontal, rotating reactors to determine suitable conditions for the scale-up of the fermentation to a pilot-scale 50 L reactor. Using virgin pulp PS (VP-PS) and corrugated recycle PS (CR-PS) at solids loadings of up to 40% (w/w), ethanol concentrations of 100.9 and 73.3 g/L, respectively, were achieved. Furthermore, genetically engineered, xylose-utilising, cellulase-secreting yeast strains allowed a decrease in the exogenous enzyme requirements up to 50%. The lab-scale results were comparable to the typical performance of 1G ethanol production processes and far exceeded the target concentration of 40 g/L for economically feasible 2G ethanol production. SStF of whole sugarcane at lab scale yielded results that were technically comparable to the conventional sugarcane-to-ethanol fermentation process. The inoculum size and rotation speed of the reactor had significant effects on the fermentation efficiency, with the maximum ethanol concentration of 86.7 g/L, corresponding to 90.5% of the theoretical maximum yield, achieved at 5 rpm and an inoculum size of 5% (w/w). Compared to lab-scale experiments, no significant decreases in ethanol concentrations or ethanol yields were observed during SStF of PS and whole sugarcane in a 50 L pilot-scale bioreactor. The specific reactor and impeller configuration facilitated effective mixing that was critical to achieve efficient conversion of both substrates to ethanol. This work successfully demonstrated the application of SStF for the conversion of PS and whole sugarcane to ethanol up to 50 L pilot scale, providing preliminary data for the eventual aim of industrialisation of PS and whole sugarcane fermentation. Collectively, the insights gained are not only limited to PS and sugarcane but can be expanded to other lignocellulosic and sugar-rich substrates or organic waste streams such as food- and municipal waste. AFRIKAANSE OPSOMMING: Geen opsomming beskikbaar. Doctoral 2025-06-04T12:11:49Z 2025-06-04T12:11:49Z 2025-03 Thesis https://scholar.sun.ac.za/handle/10019.1/132347 en Stellenbosch University xv, 129 pages : illustrations application/pdf Stellenbosch : Stellenbosch University |
| spellingShingle | Solid-state fermentation Sugarcane -- Biotechnology Biomass conversion Lignocellulose -- Biotechnology Lignocellulose -- Biotechnology UCTD Van Dyk, Janke Solid-state fermentation of whole sugarcane and paper sludge for first- and second-generation ethanol production |
| title | Solid-state fermentation of whole sugarcane and paper sludge for first- and second-generation ethanol production |
| title_full | Solid-state fermentation of whole sugarcane and paper sludge for first- and second-generation ethanol production |
| title_fullStr | Solid-state fermentation of whole sugarcane and paper sludge for first- and second-generation ethanol production |
| title_full_unstemmed | Solid-state fermentation of whole sugarcane and paper sludge for first- and second-generation ethanol production |
| title_short | Solid-state fermentation of whole sugarcane and paper sludge for first- and second-generation ethanol production |
| title_sort | solid state fermentation of whole sugarcane and paper sludge for first and second generation ethanol production |
| topic | Solid-state fermentation Sugarcane -- Biotechnology Biomass conversion Lignocellulose -- Biotechnology Lignocellulose -- Biotechnology UCTD |
| url | https://scholar.sun.ac.za/handle/10019.1/132347 |
| work_keys_str_mv | AT vandykjanke solidstatefermentationofwholesugarcaneandpapersludgeforfirstandsecondgenerationethanolproduction |