Succinic Production from Source-Separated Kitchen Biowaste in a Biorefinery Concept: Focusing on Alternative Carbon Dioxide Source for Fermentation Processes

This study presents sustainable succinic acid production from the organic fraction of household kitchen wastes, i.e., the organic fraction of household kitchen waste (OFHKW), pretreated with enzymatic hydrolysis (100% cocktail dosage: 62.5% Cellic^® CTec2, 31%% β-Glucanase and 6.5% Cellic ^® HTec2, cellulase activity of 12.5 FPU/g-glucan). For fermentation, A. succinogenes was used, which consumes CO₂ during the process. OFHKW at biomass loading > 20% (dry matter) resulted in a final concentration of fermentable sugars 81–85 g/L and can be treated as a promising feedstock for succinic production. Obtained results state that simultaneous addition of gaseous CO₂ and MgCO₃ (>20 g/dm³) resulted in the highest sugar conversion (79–81%) and succinic yields (74–75%). Additionally, CH₄ content in biogas, used as a CO₂ source, increased by 21–22% and reached 91–92% vol. Liquid fraction of source-separated kitchen biowaste and the residue after succinic fermentation were successfully converted into biogas. Results obtained in this study clearly document the possibility of integrated valuable compounds (succinic acid) and energy (biogas) production from the organic fraction of household kitchen wastes (OFHKW).