Hydrothermal pretreatment of brewer's spent grain: A pathway to sustainable biogas production and waste valorization

Producción Científica

Brewer’s spent grain (BSG), a by-product of the brewing industry, faces significant waste management challenges but holds potential as a substrate for biogas production via anaerobic digestion (AD). However, its lignocellulosic complexity limits microbial degradation and methane yield. In previous studies by our research group, various treatment strategies for BSG were explored, including approaches aimed at recovering high-value compounds. Building upon this foundation, the present work evaluates the potential of hydrothermal pretreatment to enhance methane production from BSG via AD. The novelty lies in the combination of a continuous hydrothermal pre- treatment reactor with meta-transcriptomic analysis of the anaerobic digestion process, enabling a direct cor- relation between operational performance and microbial functional shifts. Hydrothermal pretreatment was applied to partially hydrolyze cellulose and hemicellulose into fermentable sugars, improving biodegradability while minimizing the formation of inhibitory compounds. Results showed that hydrothermally pretreated BSG supported methane productions over 1500 mL CH4/L_reactor⋅day, markedly higher than the 100–500 mL CH4/ L_reactor⋅day observed for untreated BSG. Volatile solids degradation efficiency improved by 30 %, while methane content in biogas increased from 30 % to 65 %. Genomic analysis of the microbial consortium revealed enhanced activity of methanogenic archaea and fermentative bacteria associated with the increased methane production. This integrated approach not only disrupts lignocellulosic barriers more effectively but also provides deeper insights into microbial functionality, reinforcing hydrothermal pretreatment as a viable strategy for boosting biogas yield and advancing sustainable waste-to-energy solutions.

BiOBreW project, which is funded by the European Union's Horizon MSCA 2021-PF-01 research and innovation programme, under grant agreement N° 101065428

Junta de Castilla y León y del programa FEDER de la UE (UIC 379)

Agencia Estatal de Investigación (AEI) (Project TED2021-129837B-C42)

Junta de Castilla y León y del programa FEDER de la UE (CLU-2019-04)

Ministerio de Ciencia, Innovación y Universidades de España (beca «Beatriz Galindo» BEAGAL18/00247)