Application of Anaerobic Co-digestion of Brewery by-Products for Biomethane and Bioenergy Production in a Biorefinery Concept

Abstract

This study investigated the anaerobic co-digestion (AcoD) of brewery by-products for biomethane and bioenergy recovery, focusing on operational performance evaluation, kinetic analysis, microbial metataxonomic, and metabolic function prediction. The biochemical methane potential was conducted under mesophilic (35 °C) and methanogenic conditions (pH 7.5) by mixing brewery wastewater and sludge from the brewery wastewater treatment plant (1:1, v/v), following the addition (2.5 – 12.5 %, w/v) of brewer’s spent grains (BSG). The results demonstrate that the highest methane yield (88.02 mL CH4/g TVS) was obtained with 12.5 % BSG, which was 20.66-fold higher than the control reactor operated with wastewater and sludge (4.26 mL CH4/g TVS). The bioenergy recovery from biomethane could generate electricity (0.348 kWh/kg TVS) and heat (1556 MJ/kg TVS), avoiding greenhouse gas emissions (0.114 kg CO2-eq/kg TVS). The microbial community dynamics revealed a predominance of Halobacterota, Chloroflexi, and Euryarchaeota phylum. The genera Methanosaeta and Methanobacterium, and the Anaerolineaceae family predominated in the AcoD process. The metabolic function prediction showed the presence of genes (K01895, K00193, K00625, and K00925) associated with the direct activation of acetate in the acetoclastic pathway and methane production. Finally, the data obtained provide a perspective on using brewery by-products for bioenergy production in a biorefinery concept, reducing the environmental impacts and contributing to the circular bioeconomy transition of the beer industry.