Full Text Available
Note: Clicking the button above will open the full text document at the original institutional repository in a new window.
A thermosiphon photobioreactor for photofermentative hydrogen production by Rhodopseudomonas palustris.
Thesis (MEng)--Stellenbosch University, 2023.
Saved in:
| Main Author: | |
|---|---|
| Other Authors: | |
| Format: | Thesis |
| Language: | en_ZA en_ZA |
| Published: |
Stellenbosch : Stellenbosch University
2023
|
| Subjects: | |
| Tags: |
No Tags, Be the first to tag this record!
|
| _version_ | 1867613913738117120 |
|---|---|
| access_status_str | Open Access |
| author | Bosman, Catharine Elizabeth |
| author2 | Pott, Robert William M. |
| author_browse | Bosman, Catharine Elizabeth Pott, Robert William M. |
| author_facet | Pott, Robert William M. Bosman, Catharine Elizabeth |
| author_sort | Bosman, Catharine Elizabeth |
| collection | Thesis |
| dc_rights_str_mv | Stellenbosch University |
| description | Thesis (MEng)--Stellenbosch University, 2023. |
| format | Thesis |
| id | oai:scholar.sun.ac.za:10019.1/127248 |
| institution | Stellenbosch University (South Africa) |
| language | en_ZA en_ZA |
| last_indexed | 2026-06-10T12:43:41.995Z |
| license_str | Other — see source repository |
| provenance_str_mv | Harvested via OAI-PMH from SUNScholar — Stellenbosch University Repository |
| publishDate | 2023 |
| publishDateRange | 2023 |
| publishDateSort | 2023 |
| publisher | Stellenbosch : Stellenbosch University |
| publisherStr | Stellenbosch : Stellenbosch University |
| record_format | dspace |
| source_str | SUNScholar — Stellenbosch University Repository |
| spelling | oai:scholar.sun.ac.za:10019.1/127248 A thermosiphon photobioreactor for photofermentative hydrogen production by Rhodopseudomonas palustris. Bosman, Catharine Elizabeth Pott, Robert William M. Bradshaw, Steven Martin Stellenbosch University. Faculty of Engineering. Dept. of Process Engineering. Hydrogen -- Biotechnology Thermosiphon photobioreactor Fermentation Computational fluid dynamics Rhodopseudomonas Thermosiphon photobioreactor Thesis (MEng)--Stellenbosch University, 2023. ENGLISH ABSTRACT: Hydrogen has widely been identified as a commodity chemical. Currently, however, hydrogen is primarily produced through non-renewable methods. Biological hydrogen production through microbial photofermentation offers an environmentally friendly and potentially economically feasible alternative. Although this technology is promising, the costs associated with photofermentation systems need to be reduced and hydrogen productivity increased, to make the technology a competitive alternative to non-renewable hydrogen production methods. This can potentially be realised through cost-reduction strategies in combination with bioremediation – purifying wastewater whilst simultaneously producing a valuable chemical. This work applied a combination of techniques to develop and evaluate a novel thermosiphon photobioreactor (TPBR) for photofermentative hydrogen production, using Rhodopseudomonas palustris (R. palustris). The TPBR implements the thermosiphon effect to passively circulate biomass – the first and currently the only photobioreactor with the potential of operating without any external energy inputs. The TPBR was successfully implemented for photofermentative hydrogen production using R. palustris, achieving maximum hydrogen production rates of up to 0.310 mol·m−3 ·h−1 in the growing state. The effects of light intensity, temperature and biomass concentration on hydrogen production and passive circulation of biomass were investigated. The effects of biomass concentration were found to be most pronounced (0.4 to 1.2 g·L−1 ), while light intensities of 400 to 600 W·m−2 and an internal operating temperature of 31 to 44 °C were found to be suitable for hydrogen production. Exploring the effects of geometry, two novel TPBR designs were proposed – a tubular loop TPBR and a flat-plate TPBR. Using computational fluid dynamics (CFD) simulations, these designs were characterized in terms of fluid flow patterns, temperature profiles and radiation fields. Both TPBR designs showed potential for hydrogen production, achieving temperature gradients sufficient to ensure adequate circulation and velocities to maintain biomass in suspension. CFD simulations indicated light distribution as a possible area for improvement in the existing TPBR. Consequently, a reflector system was developed and implemented for the enhancement of light distribution and hydrogen production in the experimental TPBR – achieving a more uniform light field and an associated 48% increase in hydrogen production. Evaluating the feasibility of outdoor operation, the effects of diurnal light cycles and the emission spectrum of light were investigated. R. palustris was able to produce hydrogen under a sunlight-mimicking light emission spectrum achieving maximum hydrogen production rates of 0.790 mol·m−3 ·h−1 , albeit slightly lower as compared to under near-infrared light where it reached production rates up to 0.891 mol·m−3 ·h−1 . Hydrogen production was found to cease during dark periods in the diurnal light cycles; however, continuing again in the presence of light and achieving maximum Stellenbosch University https://scholar.sun.ac.za iii hydrogen production rates of ~0.015 mol·m−3 ·h−1 . This demonstrated promising potential towards outdoor operation of the TPBR, circumventing the requirement for external energy inputs. This dissertation has successfully demonstrated the application of a novel thermosiphon photobioreactor for photofermentative hydrogen production with minimal external energy input. The research comprised determination of suitable operating conditions for hydrogen production, a CFD modelling method for the design of PBRs, two novel TPBR designs and characterization thereof, a light distribution strategy for the enhancement of hydrogen productivity in PBRs, and insight into the passive circulation of biomass in a TPBR and the behaviour of R. palustris under simulated outdoor conditions. Collectively, this research provides knowledge not only improving the TPBR, but which could also be extended to other systems in the biohydrogen field. AFRIKAANS OPSOMMING: Waterstof word wyd geïdentifiseer as ’n kommoditeitchemikalie. Tans word waterstof egter primêr geproduseer deur nie-herwinbare metodes. Biologiese waterstofproduksie deur mikrobiese fotofermentasie bied ’n omgewingsvriendelike en potensieel ekonomies uitvoerbare alternatief. Al is hierdie tegnologie belowend, moet die kostes geassosieer met die fotofermentasiesisteme verminder word en waterstofproduktiwiteit verhoog word om die tegnologie ’n kompeterende alternatief vir nieherwinbare waterstofproduksiemetodes te maak. Hierdie kan potensieel gerealiseer word deur kostereduksiestrategieë in kombinasie met bioremediëring – suiwering van afvalwater terwyl ’n waardevolle chemikalie gelyktydig geproduseer word. Hierdie werk het ’n kombinasie tegnieke toegepas om ’n nuwe termosifonfotobioreaktor (TPBR) vir fotofermentatiewe waterstofproduksie te ontwikkel en evalueer, deur Rhodopseudomonas palustris (R. Palustris) te gebruik. Die TPBR implementeer die termosifon se effek om biomassa passief te sirkuleer - die eerste en tans die enigste fotobioreaktor met die potensiaal om sonder eksterne energieinsette bedryf te word. Die TPBR is suksesvol geïmplementeer vir fotofermentatiewe waterstofproduksie deur R. palustris te gebruik, met maksimum waterstofproduksietempo’s wat tot en met 0.310 mol·m-3 ·h-1 bereik het in die groeiende fase. Die effekte van ligintensiteit, temperatuur en biomassakonsentrasie op waterstofproduksie en passiewe sirkulasie van biomassa is ondersoek. Die effek van biomassakonsentrasie is gevind om die mees prominent te wees (0.4 tot 1.2 g·L-1 ), terwyl ligintensiteite van 400 tot 600 W·m-2 en ’n bedryfstemperatuur van 31 tot 44 °C gevind is om die mees gepas te wees vir waterstofproduksie. Toe die effek van geometrie ondersoek is, is twee nuwe ontwerpe voorgestel – ’n buisvormige lus TPBR en ’n platplaat TPBR. Deur rekenkundige vloei dinamika (CFD) simulasies te gebruik, is hierdie ontwerpe gekarakteriseer in terme van vloeistofvloeipatrone, temperatuurprofiele en radiasievelde. Beide TPBR-ontwerpe het potensiaal getoon vir waterstofproduksie, met temperatuurgradiënte genoegsaam om voldoende sirkulasie en snelhede van biomassa in suspensie te handhaaf. CFD-simulasies het ligverspreiding as ’n moontlike area vir verbetering in die bestaande TPBR aangedui. Vervolgens is ’n reflektorsisteem ontwikkel en geïmplementeer vir die verryking van ligverspreiding en waterstofproduksie in die eksperimentele TPBR – wat ’n meer uniforme ligveld bereik het en ’n geassosieerde 48% verhoging in waterstofproduksie. Om die uitvoerbaarheid van buite-bedryf te evalueer, is die effekte van daaglikse ligsiklusse en die emissiespektrum van lig, ondersoek. R. palustris kon waterstof onder ’n sonlignagebootste ligemissiespektrum produseer met maksimum waterstofproduksietempo’s van 0.790 mol·m−3 ·h−1 , alhoewel teen effens laer produksietempo’s in vergelyking met naby-infrarooilig, waar waterstofproduksietempo’s van 0.891 mol·m−3 ·h−1 bereik is. Waterstofproduksie is gevind om te Stellenbosch University https://scholar.sun.ac.za v eindig gedurende donker periodes in die daaglikse siklus; maar weer voort te gaan in die teenwoordigheid van lig en maksimum waterstofproduksietempo’s van ~0.015 mol·m-3 ·h-1 te bereik. Hierdie demonstreer belowende potensiaal vir buite-bedryf van die TPBR, wat die vereiste vir eksterne energie-insette ontduik. Hierdie dissertasie het die toepassing van ’n nuwe termosifonfotobioreaktor vir fotofermentatiewe waterstofproduksie met minimale eksterne energie-insette, suksesvol gedemonstreer. Die navorsing het bestaan uit die bepaling van gepaste bedryfskondisies vir waterstofproduksie, ’n CFDmodelleringsmetode vir die ontwerp van PBR’e, twee nuwe TPBR-ontwerpe en karakterisering daarvan, ’n ligverspreidingstrategie vir die verbetering van waterstofproduksie in PBR’e, en insig in die passiewe sirkulasie van biomassa in ’n TPBR en die gedrag van R. Palustris onder gesimuleerde buite kondisies. Al hierdie navorsing saam verskaf kennis nie slegs om die TPBR te verbeter nie, maar wat ook uitgebrei kan word na ander sisteme in die biowaterstofveld. Doctoral 2023-03-03T11:54:36Z 2023-05-18T07:11:55Z 2023-03-03T11:54:36Z 2023-05-18T07:11:55Z 2023-03 Thesis http://hdl.handle.net/10019.1/127248 en_ZA en_ZA Stellenbosch University xxi, 225 pages : illustrations application/pdf Stellenbosch : Stellenbosch University |
| spellingShingle | Hydrogen -- Biotechnology Thermosiphon photobioreactor Fermentation Computational fluid dynamics Rhodopseudomonas Thermosiphon photobioreactor Bosman, Catharine Elizabeth A thermosiphon photobioreactor for photofermentative hydrogen production by Rhodopseudomonas palustris. |
| title | A thermosiphon photobioreactor for photofermentative hydrogen production by Rhodopseudomonas palustris. |
| title_full | A thermosiphon photobioreactor for photofermentative hydrogen production by Rhodopseudomonas palustris. |
| title_fullStr | A thermosiphon photobioreactor for photofermentative hydrogen production by Rhodopseudomonas palustris. |
| title_full_unstemmed | A thermosiphon photobioreactor for photofermentative hydrogen production by Rhodopseudomonas palustris. |
| title_short | A thermosiphon photobioreactor for photofermentative hydrogen production by Rhodopseudomonas palustris. |
| title_sort | thermosiphon photobioreactor for photofermentative hydrogen production by rhodopseudomonas palustris |
| topic | Hydrogen -- Biotechnology Thermosiphon photobioreactor Fermentation Computational fluid dynamics Rhodopseudomonas Thermosiphon photobioreactor |
| url | http://hdl.handle.net/10019.1/127248 |
| work_keys_str_mv | AT bosmancatharineelizabeth athermosiphonphotobioreactorforphotofermentativehydrogenproductionbyrhodopseudomonaspalustris AT bosmancatharineelizabeth thermosiphonphotobioreactorforphotofermentativehydrogenproductionbyrhodopseudomonaspalustris |