Phd in ENVIRONMENTAL AND HYDRAULIC ENGINEERING

Thesis title: Modelli metabolici per la produzione di H2 mediante dark fermentation di substrati organici biodegradabili

Hydrogen is one of the most promising candidates for replacing fossil fuels in the context of the energy transition. However, the production processes currently used involve fossil fuels and massive energy inputs, while biological processes, including fermentation, represent a promising alternative approach for hydrogen’s sustainable production. Fermentation is an extremely complex biological process, influenced by numerous factors having a great impact on final yield and rate. Hence, understanding the biochemical mechanisms is of fundamental to improve the performance of the process and make it suitable for the production of hydrogen for energy purposes. The research aimed at contributing to the knowledge improvement of the complex dark fermentation metabolic process, with particular regard to the production of hydrogen from lactose-rich organic substrates. It was decided to adopt the Flux Balance Analysis (FBA), a constrained-based modeling approach based on the assumption of the quasi-steady state. FBA allows to describe the metabolic behaviour by reducing the complexity of kinetic mathematical models. Starting from the data available in the literature, two new metabolic networks have been developed, based on the principle of “universal bacterium”. These networks were first validated using series of experimental data, identified through a bibliographic search, then used to improve the level of understanding of whey fermentation process by indigenous biomass, in different pH conditions. Finally, a simulation was carried out to identify the optimal conditions to maximize the hydrogen production rate during two different stages of the process.