Integral process assessment of sugarcane agricultural crop residues conversion to ethanol

•Alkali and steam explosion pretreatments were effective for sugarcane agricultural crop residues (ACR).•The addition of hemicellulases to cellulases boosted in 60% glucose release from alkali pretreated biomass.•2G ethanol efficiencies up to 80% were reached at 20% (w/v) solids loading.•4.8% and 3.2% (w/w) of 2G ethanol were produced by PSSF after alkali and steam explosion pretreatments, respectively. This work focuses a whole process assessment on post-harvesting sugarcane residues for 2G ethanol production by different saccharification-fermentation conditions at high solids loading, performed after steam explosion, alkaline and acidic pretreatments. Carbohydrate recoveries and enzymatic digestibility results showed that alkali and steam explosion pretreatments were effective for the biomass assayed. Due to a significant improvement (60%) of the glucose released by combining hemicellulases and cellulases only after the NaOH pretreatment, the most favorable process settled comprised an alkali-based pretreatment followed by a pre-saccharification and simultaneous saccharification and fermentation (PSSF). The produced ethanol reached 4.8% (w/w) as a result of an 80% conversion of the glucose from the pretreated biomass. Finally, an ethanol concentration of 3.2% (w/w) was obtained by means of a steam explosion followed by PSSF, representing a suitable start point to further develop a low environmental impact alternative for ethanol production.