PhD Defence by Francesco Vigato

Principal supervisor
Senior Researcher Merlin Alvarado-Morales

Co-supervisor
Professor John M. Woodley

Examiners
Associate Professor Helena Junicke (chair)
DTU Chemical and Biochemical Engineering 

Scientific Manager Tsapekos Panagiotis
Novo Nordisk Foundation, Denmark

Professor Steven De Meester
University of Ghent, Belgium

Chairperson at defence
Professor Manuel Pinelo
DTU Chemical and Biochemical Engineering

Popular Science Summary

The Ph.D. thesis explored the role of carbon dioxide (CO2) in succinic acid fermentation process, offering a sustainable and green perspective to this technology. The research
investigates the behavior of CO2 in batch fermentation, utilizing sugar-rich industrial waste from a candy factory as the organic substrate. Achieving a final succinic acid titer of 25 g/L,
with a remarkable 82% bio-methane purity, the research demonstrates the potential of this eco-friendly approach.
Furthermore, a novel mechanistic model is introduced for continuous stirred-tank reactor (CSTR) systems, enhancing the understanding of the intricate dynamics between CO2
concentration, microbial activity, and product formation. This model, successfully validated at lab-scale conditions, not only captures the distribution of carbon at varying CO2
concentrations but also provides insights into controlling succinic acid production over byproducts formation.
Finally, the specific production rate, previously developed, is incorporated in a new mechanistic model to predict the fermentation outcome of a packed bed reactor. The model,
successfully validated at different steady states, is capable of showing the variables profiles over the reactor length and spot substrates limiting area.
By studying the complexities of CO2 influence on fermentation, this research not only advances the understanding of succinic acid fermentation process but also introduced a new
methodology to promote the CO2 fixation without compromising the final performances. In essence, this work marks a crucial step towards the development of environmentally
conscious and economically viable biotechnological processes.