Modelling and testing of a light reflector system for the enhancement of biohydrogen production in a thermosiphon photobioreactor

• Published in: Journal of biotechnology 2023-01, Vol.361, p.57-65
• Main Authors: Bosman, Catharine Elizabeth, Pott, Robert William McClelland, Bradshaw, Steven Martin
• Format: Article
• Language: English
• Subjects: Biohydrogen; Biomass; carbon; Fermentation; fluid mechanics; Glycerol; Hydrogen; hydrogen production; Light distribution; Photobioreactor; Photobioreactors; Photofermentation; Rhodopseudomonas palustris
• ISSN: 0168-1656; 1873-4863
• DOI: 10.1016/j.jbiotec.2022.11.016

One of the main factors affecting hydrogen production and growth of photofermentative microorganisms is light; low light penetration and utilization are significant bottlenecks in photofermentative hydrogen production systems. In this study, light distribution in a thermosiphon photobioreactor operated with Rhodopseudomonas palustris was investigated. Radiation fields were modelled and simulated using computational fluid dynamics (ANSYS® Fluent, 2019 R2) and a reflector system was evaluated for the enhancement of light distribution in a thermosiphon photobioreactor. The effect of the reflector system was investigated experimentally in terms of hydrogen production, carbon substrate consumption and biomass circulation in the reactor. With the addition of the reflector system, hydrogen production was increased by 48% while glycerol consumption was increased from approximately 24% to 32%. After 336 h, the concentration of R. palustris cells still in suspension ranged from 0.13 to 0.18 g∙L−1, with no discernible difference in concentration between the systems with and without reflectors. Collectively, the reflector system was shown to be a viable option in enhancing light distribution in photobioreactors, with an associated increase in both hydrogen production as well as glycerol consumption. •Computational fluid dynamics can be used to model light in photobioreactors.•Reflectors can be used as a light distribution strategy in photobioreactors.•Reflectors can increase R. palustris hydrogen production and glycerol consumption.•Productivity of a thermosiphon photobioreactor can be increased with reflectors.