Lignocellulosic bioethanol production with revalorization of low-cost agroindustrial by-products as nutritional supplements

• Agro-industrial residues were re-valorized as fermentation media supplements.
• Supplementation allowed the reduction of fermentation times.
• Supplementation effect was demonstrated in multiple process configurations.
• Supplementation made SSF process feasible.
• Process intensification was achieved.

During the pretreatment of lignocellulosic biomass for second generation bioethanol production, fermentation inhibitors are released. To overcome this, the use of a robust industrial strain together with agro-industrial by-products as nutritional supplementation was proposed to increase ethanol productivity and yields. Two factorial experimental designs were carried out to optimize fermentation of hydrolysate from autohydrolysis of Eucalyptus globulus. The most influential variables on ethanol production were cheese whey and K2O5S2 (potassium metabisulfite) supplementation. Nutrient addition effect was demonstrated using the whole slurry from autohydrolysis in two process configurations (separate hydrolysis and fermentation, SHF and simultaneous saccharification and fermentation, SSF). Comparing the supplemented SHF and SSF assays with non-supplemented, 2.3 and 7.4 fold higher ethanol concentrations were obtained, respectively. In the case of SSF, 50.4 g L−1 of ethanol concentration and 92.2% of ethanol conversion were attained, demonstrating an improved fermentation performance in industrial lignocellulose fermentations.