Full Text Available
Note: Clicking the button above will open the full text document at the original institutional repository in a new window.
Enhancing the biomethane production of alkaline pre-treated lignocellulosic waste through bioaugmentation of anaerobic digestion
van Wyk, J. K. D. 2025. Enhancing the biomethane production of alkaline pre-treated lignocellulosic waste through bioaugmentation of anaerobic digestion. Unpublished masters thesis. Stellenbosch: Stellenbosch University [online]. Available: https://scholar.sun.ac.za/items/f400411e-1961-4eb2-8606-e14...
Saved in:
| Main Author: | |
|---|---|
| Other Authors: | |
| Format: | Thesis |
| Language: | English |
| Published: |
Stellenbosch : Stellenbosch University
2025
|
| Subjects: | |
| Tags: |
No Tags, Be the first to tag this record!
|
| _version_ | 1867614127555346432 |
|---|---|
| access_status_str | Open Access |
| author | Van Wyk, Jamie Kate Danielle |
| author2 | Van Rensburg, Eugene |
| author_browse | Van Rensburg, Eugene Van Wyk, Jamie Kate Danielle |
| author_facet | Van Rensburg, Eugene Van Wyk, Jamie Kate Danielle |
| author_sort | Van Wyk, Jamie Kate Danielle |
| collection | Thesis |
| dc_rights_str_mv | Stellenbosch University |
| description | van Wyk, J. K. D. 2025. Enhancing the biomethane production of alkaline pre-treated lignocellulosic waste through bioaugmentation of anaerobic digestion. Unpublished masters thesis. Stellenbosch: Stellenbosch University [online]. Available: https://scholar.sun.ac.za/items/f400411e-1961-4eb2-8606-e14d0e55e6d2 |
| format | Thesis |
| id | oai:scholar.sun.ac.za:10019.1/132293 |
| institution | Stellenbosch University (South Africa) |
| language | English |
| last_indexed | 2026-06-10T12:47:05.324Z |
| 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:10019.1/132293 Enhancing the biomethane production of alkaline pre-treated lignocellulosic waste through bioaugmentation of anaerobic digestion Van Wyk, Jamie Kate Danielle Van Rensburg, Eugene Gorgens, Johann F. Stellenbosch University. Faculty of Engineering. Dept. of Chemical Engineering. Lignocellulose -- Biodegradation Hydrolysis Sewage -- Purification -- Anaerobic treatment Corn stover UCTD van Wyk, J. K. D. 2025. Enhancing the biomethane production of alkaline pre-treated lignocellulosic waste through bioaugmentation of anaerobic digestion. Unpublished masters thesis. Stellenbosch: Stellenbosch University [online]. Available: https://scholar.sun.ac.za/items/f400411e-1961-4eb2-8606-e14d0e55e6d2 Thesis (MEng)--Stellenbosch University, 2025. ENGLISH ABSTRACT: The recalcitrant and crystalline lignocellulose structure is mainly composed of cellulose, hemicellulose and lignin; this physicochemical structure limits its exploitation during anaerobic digestion (AD), which is strongly dependent on the hydrolytic activity of the inherent microbial consortium. Hydrolysis is, therefore, regarded as the rate-limiting step of lignocellulosic AD. A pre-treatment is necessary to gain access to the cellulose and hemicellulose and enhance the enzymatic hydrolysis into fermentable sugars. Bioaugmentation is the practice of supplementing a pure or consortium of specialised micro-organisms into an established system to enhance the performance of the inherent micro-organisms. This study aimed to determine the effect of bioaugmentation on improving the hydrolysis and subsequent biomethane production with pre-treated corn stover (PCS) as the lignocellulosic biomass. The augmenting micro-organisms namely, Bacillus subtilis, Bacillus licheniformis and Serratia marcescens, primarily served as cell factories to produce the cellulolytic enzymes for polymer degradation, as opposed to supplementing the culture with expensive, commercial enzymes. To improve the substrate digestibility before subjection to bioaugmentation-AD, all of the corn stover (CS) was pre-treated using a low-severity, alkaline treatment of ammonium hydroxide (15% NH₃; 12 hours; 60 °C). Initially, biochemical methane potential (BMP) assays were carried out at 37 °C and an inoculum-to-substrate ratio (ISR) of 2:1 to determine the preferred treatment configuration between mono- and co-digestion of CS/PCS and food waste (FW) as a co-substrate, to maximise the biomethane yield (mL/g VS). Thereafter, the effect of bioaugmentation was investigated on the selected AD configuration of PCS co-digested with FW at a carbon-to-nitrogen (C:N) ratio of 30:1. B. subtilis, B. licheniformis and S. marcescens were introduced into the AMPTS (600mL) reactors as pure, independent cultures starting at a standardised concentration of 4x10¹⁰ CFU/mL with corresponding dry cell weights (DCW) of 0.097 g/L, 0.017 g/L and 0.016 g/L. An inoculation ratio of 10% (v/v) was utilised, which resulted in a final concentration of 4x10⁹ CFU/mL reactor volume after inoculation. The concentration of the pure cultures was increased incrementally to determine the minimum microbial loading required to positively affect digestion performance. Overall, the treatment of B. subtilis with 6.43% total solids loading corresponding to an augmentation, inoculum and substrate loading of 4.850 g DCW/L ( 2x10¹² CFU/mL), 42.21 g DCW/L and 17.22 g DCW/L, respectively, provided the highest yield (525.35mL CH4/g VS) enhancement of 33.52% (p<0.05). Moreover, augmentation of the various bacteria at a concentration of 1.2 x 10¹² CFU/mL (0.77-4.53% of the total solid loading), attained the highest volumetric productivity rates (VPR) of 0.97-1.04 mL/mL-1 day-1. Genomic sequencing of the microbial community at the end of the BMP AD runs revealed an increase in microbial diversity (α-diversity) compared to the initial inoculum, where the Firmicutes phylum remained the dominant bacterial phylum. Although bioaugmentation was successfully implemented in optimal lab-scale conditions, digester failure owing to acidification occurred at the pilot-scale level (30 L). Nevertheless, this research highlighted that pure culture bioaugmentation of lignocellulose AD can (i) improve lignocellulose hydrolysis, (ii) enhance biomethane yields, (iii) reduce the digestion time and (iv) promote the growth of particular micro-organisms. AFRIKAANSE OPSOMMING: Geen opsomming beskikbaar. Masters 2025-06-03T06:06:30Z 2025-06-03T06:06:30Z 2025-03 Thesis https://scholar.sun.ac.za/handle/10019.1/132293 en Stellenbosch University xiii, 132 pages : illustrations application/pdf Stellenbosch : Stellenbosch University |
| spellingShingle | Lignocellulose -- Biodegradation Hydrolysis Sewage -- Purification -- Anaerobic treatment Corn stover UCTD Van Wyk, Jamie Kate Danielle Enhancing the biomethane production of alkaline pre-treated lignocellulosic waste through bioaugmentation of anaerobic digestion |
| title | Enhancing the biomethane production of alkaline pre-treated lignocellulosic waste through bioaugmentation of anaerobic digestion |
| title_full | Enhancing the biomethane production of alkaline pre-treated lignocellulosic waste through bioaugmentation of anaerobic digestion |
| title_fullStr | Enhancing the biomethane production of alkaline pre-treated lignocellulosic waste through bioaugmentation of anaerobic digestion |
| title_full_unstemmed | Enhancing the biomethane production of alkaline pre-treated lignocellulosic waste through bioaugmentation of anaerobic digestion |
| title_short | Enhancing the biomethane production of alkaline pre-treated lignocellulosic waste through bioaugmentation of anaerobic digestion |
| title_sort | enhancing the biomethane production of alkaline pre treated lignocellulosic waste through bioaugmentation of anaerobic digestion |
| topic | Lignocellulose -- Biodegradation Hydrolysis Sewage -- Purification -- Anaerobic treatment Corn stover UCTD |
| url | https://scholar.sun.ac.za/handle/10019.1/132293 |
| work_keys_str_mv | AT vanwykjamiekatedanielle enhancingthebiomethaneproductionofalkalinepretreatedlignocellulosicwastethroughbioaugmentationofanaerobicdigestion |