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Steam pretreatment of wheat straw and sugarcane bagasse to produce feed for black soldier fly larvae
Thesis (MEng) -- Stellenbosch University, 2022.
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| Format: | Thesis |
| Language: | en_ZA |
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Stellenbosch : Stellenbosch University
2022
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| _version_ | 1867613921177763840 |
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| access_status_str | Open Access |
| author | Theron, Werner |
| author2 | Gorgens, Johann F. |
| author_browse | Gorgens, Johann F. Theron, Werner |
| author_facet | Gorgens, Johann F. Theron, Werner |
| author_sort | Theron, Werner |
| collection | Thesis |
| dc_rights_str_mv | Stellenbosch University |
| description | Thesis (MEng) -- Stellenbosch University, 2022. |
| format | Thesis |
| id | oai:scholar.sun.ac.za:10019.1/126195 |
| institution | Stellenbosch University (South Africa) |
| language | en_ZA |
| last_indexed | 2026-06-10T12:43:49.382Z |
| license_str | Other — see source repository |
| provenance_str_mv | Harvested via OAI-PMH from SUNScholar — Stellenbosch University Repository |
| publishDate | 2022 |
| publishDateRange | 2022 |
| publishDateSort | 2022 |
| publisher | Stellenbosch : Stellenbosch University |
| publisherStr | Stellenbosch : Stellenbosch University |
| record_format | dspace |
| source_str | SUNScholar — Stellenbosch University Repository |
| spelling | oai:scholar.sun.ac.za:10019.1/126195 Steam pretreatment of wheat straw and sugarcane bagasse to produce feed for black soldier fly larvae Theron, Werner Gorgens, Johann F. Stellenbosch University. Faculty of Engineering. Dept. of Process Engineering. Cellulase -- Biotechnology Lignocellulose Wheat straw Enzymatic hydrolysis UCTD Thesis (MEng) -- Stellenbosch University, 2022. ENGLISH ABSTRACT: The cultivation of black soldier fly larvae (BSFL) as an alternative protein and oil source is a promising and emerging biotechnology. Lignocellulosic waste is a potential feed substrate for BSFL cultivation, although in its unprocessed form, it cannot efficiently be consumed by BSFL. The main components of lignocellulose are highly recalcitrant and require pretreatment to render it more digestible. This study evaluated steam pretreatment of lignocellulose (with and without subsequent enzymatic hydrolysis) for producing a potential feed substrate for BSFL. Wheat straw and sugarcane bagasse were stream pretreated at temperatures ranging from 140 to 215 °C. The effect of the steam pretreatment temperature and subsequent enzymatic hydrolysis on the BSFL growth was determined and the best performing pretreatment conditions were used to analyse the economic feasibility of an industrial BSFL production plant. Steam pretreatment alone showed an increase in BSFL growth over the control (raw lignocellulose); however, the dry bioconversions (<10%) were still substantially lower than the highest dry bioconversions (>14%) reported in literature. In contrast, enzymatic hydrolysis subsequent to steam pretreatment increased BSFL growth to such an extent that at a pretreatment temperature of 185 °C, the BSFL dry bioconversion (14% - 16%) was comparable to that of literature. The inability of BSFL to effectively digest liberated cellulose and hemicellulose, after pretreatment alone, was further supported by the fibre analysis on the BSFL feeds and residues which showed low decreases (< 5 g) in the fibre content during BSFL rearing. It was concluded that whereas steam pretreatment renders the lignocellulosic BSFL feed substrates more digestible, a subsequent enzymatic hydrolysis step was required to sustain adequate BSFL growth. The high sugar content of the feed substrates had the most prominent effect over the toxicity of the inhibitors at a steam pretreatment temperature of 185 °C. However, the concentrations of inhibitors, generated at pretreatment temperatures greater than 185 °C was found to inhibit larval growth. It was concluded that at these higher temperatures the lignocellulosic portion of the feed substrates became toxic for the BSFL. Furfural and 5-hydroxymethylfurfural were determined to have the most toxic effect on the BSFL at concentrations greater than 0.2 g/L. Acetic acid and formic acid appeared to be better tolerated and optimal growth was still observed at concentrations below 8 g/L and 7 g/L, respectively. Furthermore, higher inhibitor concentrations at higher temperatures (> 185 °C) resulted in extremely slow BSFL growth and causing the BSFL to not acquire enough nutrients to reach the prepupal stage. The crude protein present in the BSFL decreased in comparison to that of BSFL reared on a standard BSFL feed and showed the need for protein supplementation in the BSFL feeds when lignocellulosic feedstocks were used. Techno-economic analysis revealed that the use of wheat straw in a BSFL production plant was economically feasible at a BSFL production rate of 5 t/h. The Internal rate of return of 26.6% was higher than the minimum acceptable rate of return for a medium risk investment of 20%. Although the proposed facility was economically feasible, using a standard BSFL feed instead resulted in a higher internal rate of return of 89.7%. AFRIKAANS OPSOMMING: Die kultivering van venstervlieglarwe (BSFL) as 'n alternatiewe proteïen- en oliebron is 'n belowende en ontluikende biotegnologie. Lignosellulose is 'n potensiële voersubstraat vir BSFL, alhoewel dit in sy onverwerkte vorm nie doeltreffend deur die larwes verteer kan word nie. Lignosellulose vereis voorbehandeling om dit meer verteerbaar te maak. Hierdie studie het stoomvoorbehandeling van lignosellulose (met en sonder daaropvolgende ensiematiese hidrolise) geëvalueer vir die vervaardiging van 'n potensiële voersubstraat vir BSFL. Koringstrooi en suikerriet-bagasse was stroomvoorbehandel teen temperature van 140 tot 215 °C. Die effek van die stoomvoorbehandelings temperatuur en daaropvolgende ensiematiese hidrolise op die groei van die BSFL was bepaal en die beste toestande was gebruik om ‘n ekonomiese analiese van 'n industriële produksieaanleg te doen. Stoomvoorbehandeling alleen het 'n toename in die groei van die larwes getoon in vergelyking met die kontrole (rou lignosellulose). Die droë bio-omsettings (<10%) was egter steeds aansienlik laer as die hoogste droë bio-omsettings (>14%) wat in literatuur gerapporteer was. Die ensiematiese hidrolise na stoombehandeling het die larwe-groei tot so 'n mate verhoog dat by 'n temperatuur van 185 °C, die droë bioomsetting (14% - 16%) vergelykbaar was met dié van literatuur. Die onvermoë van BSFL om vrygestelde sellulose en hemisellulose effektief te verteer, na voorbehandeling alleen, is verder ondersteun deur die veselanalise op die BSFL-voere en -reste wat lae afnames (< 5 g) in die veselinhoud tydens BSFL kultivering getoon het. Daar is tot die gevolgtrekking gekom dat waar stoomvoorbehandeling die lignosellulose in die voersubstrate meer verteerbaar maak, 'n daaropvolgende ensiematiese hidrolisestap nodig was om voldoende BSFL-groei te onderhou. Die hoë suikerinhoud van die voersubstrate het die mees prominente effek gehad oor die toksisiteit van die inhibeerders by 'n stoomvoorbehandelingstemperatuur van 185 °C. Daar is egter gevind dat die konsentrasies van inhibeerders, geproduseer by temperature hoër as 185 °C, larwegroei inhibeer. Daar is tot die gevolgtrekking gekom dat by hierdie hoër temperature die lignosellulose giftig gemaak het vir die BSFL. Furfural en 5-hidroksimetielfurfural is vasgestel om die mees toksiese effek op die BSFL te hê by konsentrasies groter as 0.2 g/L. Asynsuur en mieresuur was beter verdra en optimale groei is steeds waargeneem by konsentrasies laer as onderskeidelik 8 g/L en 7 g/L. Die proteïen teenwoordig in die BSFL het afgeneem in vergelyking met dié van BSFL wat op 'n standaard voersubstraat gekultiveer was. Dit beteken dat daar ‘n behoefte aan proteïenaanvulling in die voersubstrate is wanneer lignosellulose-voerstowwe gebruik is. Die tegno-ekonomiese analise het getoon dat die gebruik van koringstrooi in 'n BSFL-produksie-aanleg ekonomies haalbaar was teen 'n BSFL-produksietempo van 5 t/h. Die Interne opbrengskoers van 26,6% was hoër as die minimum aanvaarbare opbrengskoers vir 'n mediumrisiko-belegging van 20%. Alhoewel die voorgestelde fasiliteit ekonomies haalbaar was, het die gebruik van 'n standaard BSFL-voersubstraat 'n hoër interne opbrengskoers van 89,7% tot gevolg gehad. Masters 2022-11-23T12:37:37Z 2023-01-16T12:55:01Z 2022-11-23T12:37:37Z 2023-01-16T12:55:01Z 2022-12 Thesis http://hdl.handle.net/10019.1/126195 en_ZA Stellenbosch University xv, 134 pages : illustrations application/pdf Stellenbosch : Stellenbosch University |
| spellingShingle | Cellulase -- Biotechnology Lignocellulose Wheat straw Enzymatic hydrolysis UCTD Theron, Werner Steam pretreatment of wheat straw and sugarcane bagasse to produce feed for black soldier fly larvae |
| title | Steam pretreatment of wheat straw and sugarcane bagasse to produce feed for black soldier fly larvae |
| title_full | Steam pretreatment of wheat straw and sugarcane bagasse to produce feed for black soldier fly larvae |
| title_fullStr | Steam pretreatment of wheat straw and sugarcane bagasse to produce feed for black soldier fly larvae |
| title_full_unstemmed | Steam pretreatment of wheat straw and sugarcane bagasse to produce feed for black soldier fly larvae |
| title_short | Steam pretreatment of wheat straw and sugarcane bagasse to produce feed for black soldier fly larvae |
| title_sort | steam pretreatment of wheat straw and sugarcane bagasse to produce feed for black soldier fly larvae |
| topic | Cellulase -- Biotechnology Lignocellulose Wheat straw Enzymatic hydrolysis UCTD |
| url | http://hdl.handle.net/10019.1/126195 |
| work_keys_str_mv | AT theronwerner steampretreatmentofwheatstrawandsugarcanebagassetoproducefeedforblacksoldierflylarvae |