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Process development for ethanol production from food waste
Thesis (MEng)--Stellenbosch University, 2026.
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| Format: | Thesis |
| Language: | English |
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Stellenbosch : Stellenbosch University
2026
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| _version_ | 1867614129290739712 |
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| access_status_str | Open Access |
| author | Campbell, Kelly Susan |
| author2 | Van Rensburg, Eugene |
| author_browse | Campbell, Kelly Susan Van Rensburg, Eugene |
| author_facet | Van Rensburg, Eugene Campbell, Kelly Susan |
| author_sort | Campbell, Kelly Susan |
| collection | Thesis |
| dc_rights_str_mv | Stellenbosch University |
| description | Thesis (MEng)--Stellenbosch University, 2026. |
| format | Thesis |
| id | oai:scholar.sun.ac.za:10019.1/135668 |
| institution | Stellenbosch University (South Africa) |
| language | English |
| last_indexed | 2026-06-10T12:47:07.138Z |
| license_str | Other — see source repository |
| provenance_str_mv | Harvested via OAI-PMH from SUNScholar — Stellenbosch University Repository |
| publishDate | 2026 |
| publishDateRange | 2026 |
| publishDateSort | 2026 |
| publisher | Stellenbosch : Stellenbosch University |
| publisherStr | Stellenbosch : Stellenbosch University |
| record_format | dspace |
| source_str | SUNScholar — Stellenbosch University Repository |
| spelling | oai:scholar.sun.ac.za:10019.1/135668 Process development for ethanol production from food waste Campbell, Kelly Susan Van Rensburg, Eugene Gorgens, Johann Ferdinand Stellenbosch University. Faculty of Engineering. Dept. of Chemical Engineering. Thesis (MEng)--Stellenbosch University, 2026. Campbell, K. S. 2026. Process development for ethanol production from food waste. Unpublished masters thesis. Stellenbosch: Stellenbosch University [online]. Available: https://scholar.sun.ac.za/items/f49382de-3d5a-42f8-a920-27f3cace1139 The global demand for ethanol is expected to rapidly expand due to its potential for decarbonising the transport, chemicals, and materials sectors. Starch-rich food waste (FW) has the potential to substantially contribute to the sector. However, current bottlenecks in the implementation of ethanol production from FW include the lack of data on the availability and distribution of FW suitable for fermentation, high enzyme costs, and the high microbial burden of FW, which results in reduced yeast viability and ethanol yield. This study aimed to assess the feedstock potential and develop a process for the fermentative bioconversion of FW into ethanol. Ethanol produced was expected to meet the minimum standards for industry i.e., an ethanol concentration of 40-g/L, yield of 90%, and volumetric productivity of at least 1-g/L/h. A resource assessment was conducted to quantify and characterise FW as a feedstock in South African metropolitans. The effect of modified yeast strains, solid loadings and enzyme blends and dosages on batch and fed-batch simultaneous saccharification and fermentation (SSF) was investigated in shake-flask cultures, with scale-up of the best performing conditions to a 5-L bioreactor. The resource assessment identified two sites within Gauteng province with sufficient capacity to produce an estimated 1 464 500- and 247 860-Lethanol/annum, respectively, from February 2023 – January 2024, providing justification into the construction of an ethanol facility capable of processing FW and generating 1 000 000-L/annum. Saccharomyces cerevisiae strain Ethanol Red© (ER) and modified ER strains that exhibited amylase secretion (ER-T12) and antimicrobial peptides secretion (ER-T1E20 and ER-T1M18) were compared in shake-flask SSF. Generally, yeast strains performed similarly at solid loadings between 10% and 20% (w/v). A maximum ethanol concentration of 54.31-g/L, yield of 84.30% and productivity of 2.26-g/L/h at 20% (w/v) solid loading was recorded for ER-T1E20. Lactic and acetic acid, indicating spoilage microorganisms remained below 2.5-g/L. Without compromising performance, Liquozyme and Saczyme dosages could be decreased to 33% of the minimum supplier-recommended dosage in fed-batch SSF, whereas a combination of Liquozyme and Spriziyme allowed a decrease to 66% of the minimum recommended dosage. Furthermore, the study showed that, without supplementation of exogenous enzymes, ER-T12 performed at the same level as when enzymes were added into the process, achieving a 72-h ethanol concentration, yield and productivity of 73.29-g/L, 69.35% of the theoretical maximum and 1.02-g/L/h, respectively. The scale-up of this process produced an ethanol concentration, yield and productivity of 60.56-g/L, 58.28% and 0.84-g/L/h after 72-h. Greater levels of microbial contamination within the scale-up resulted in decreased ethanol concentrations and yields of 17% and 16%, respectively, when compared to shake-flask cultures. Despite this decrease, the study successfully demonstrated the suitability of FW as a feedstock for ethanol production while proving the robustness of ER-T12 and its effectiveness in removing exogenous enzyme requirements in a fed-batch SSF. Combining both the experimental data and resource assessment results, the feasibility of the production of over 1 000 000-Lethanol/annum using combined feedstock from sites 1 and 2, show potential for development of a commercial-scale facility, even with ethanol yields below 90%. Masters 2026-04-07T10:11:01Z 2026-04-07T10:11:01Z 2026-03 Thesis https://scholar.sun.ac.za/handle/10019.1/135668 en Stellenbosch University 192 pages : ill. application/pdf Stellenbosch : Stellenbosch University |
| spellingShingle | Campbell, Kelly Susan Process development for ethanol production from food waste |
| title | Process development for ethanol production from food waste |
| title_full | Process development for ethanol production from food waste |
| title_fullStr | Process development for ethanol production from food waste |
| title_full_unstemmed | Process development for ethanol production from food waste |
| title_short | Process development for ethanol production from food waste |
| title_sort | process development for ethanol production from food waste |
| url | https://scholar.sun.ac.za/handle/10019.1/135668 |
| work_keys_str_mv | AT campbellkellysusan processdevelopmentforethanolproductionfromfoodwaste |