EFFECT OF PRETREATMENT AND CODIGESTION ON THE BIOGAS PRODUCTION OF MICROALGUE AND CHICORY ROOTS

Anaerobic digestion is a process that is attracting growing interest from the scientific community as a pathway for sustainable energy production. Microalgae, in particular, are a focus of research due to their ability to grow rapidly on non-arable land (thus avoiding competition with food production) and their high biogas yield compared to lignocellulosic biomass. A major challenge in the anaerobic digestion of microalgae is the biodegradation of the cell wall and the solubilization of macromolecules. This study aims to deepen the understanding of how pretreatments applied to raw microalgae, targeting cell wall degradation, impact methane production by anaerobic microorganisms, as well as to examine the effects of co-digestion with chicory roots to explore potential synergistic effects. The tests evaluated ultrasound and thermal pretreatments at varying intensities, along with anaerobic co-digestion of different mixtures containing various ratios of raw microalgae and chicory roots. The results indicate that ultrasound pretreatment of Spirulina microalgae reduces methane production, while thermal pretreatment accelerates the production kinetics in the early stages but does not increase the final yield compared to untreated microalgae. Co-digestion with equal proportions of the biomasses, or with a higher proportion of microalgae, achieves greater methane production than would be expected from the digestion of each substrate individually.