Abstract

This study presents sustainable succinic acid production from lignocellulosic hydrolysates, using A. succinogenes, which consumes CO₂ during succinic fermentation. Optimal combination of carbon source (gaseous and/or solid MgCO₃, 15-30 g/dm³) and nitrogen source (mixtures of yeast extract and hydrolyzed rapeseed cakes: 100:0, 80:20, 60:40, 50:50 and 40:60 % w/w) were experimentally determined. Obtained results stated that simultaneous addition of gaseous CO₂ and MgCO₃ (20-30 g/dm³) resulted in the highest sugar conversion (89-95%) and succinic yields (66-74%). Additionally, CH₄ content in biogas, used as CO₂ source, was increased by 21-22% and reached 91-92% after succinic fermentation with addition of MgCO₃ (20 g/dm³). The course of succinic fermentation confirmed that 50% of nitrogen dosage can be added as rich in amino acids rapeseed cakes, originated from biodiesel production. Succinic fermentation with gaseous CO₂ as the only CO₂ or after replacing more than 50% of nitrogen dosage as rapeseed cakes, resulted in increased acetic and formic acids production (by-products of succinic fermentation). Optimal conditions of succinic fermentation (CO₂ source and dosage, waste nitrogen source) identified in this study can pave the way towards sustainable production of succinic acid from lignocellulosic biomass.