Different design configurations of simultaneous saccharification and fermentation to enhance ethanol production from cashew apple bagasse pretreated with alkaline hydrogen peroxide applying the biorefinery concept

Different strategies for simultaneous saccharification and fermentation (SSF) process were developed to enhance the productivity of ethanol by Kluyveromyces marxianus ATCC36907 as a part of biorefinery concept using cashew apple bagasse (CAB) as biomass. CAB was pretreated with 4.3% (v/v) alkaline hydrogen peroxide at pH 11.5 (CAB-AHP). Batch SSF conducted at 45 °C using 10% (w/v) CAB-AHP reported the highest concentration and ethanol yield. In the fed-batch SSF, the highest production (7.91 g ethanol/100g_CAB) and ethanol yield (84.69%) were achieved using 10% (w/v) CAB-AHP initial solids load, 4% solid feeding at 24 h, and the feeding of enzymes only in the beginning of the process. The recycling of pretreatment inputs decreased 50% of the batch-SSF efficiencies, saving the consumption of water, H₂O₂, and NaOH in 66.67%, 48.44%, and 66.67%, respectively. Lignin was extracted from the hydrolysate with yield of 39.2%. Thus, the proposed biorefinery concept utilizes CAB to produce ethanol with high efficiency by fed-batch SSF, pretreatment input recycling, and the utilization of the extracted lignin for future applications.