Enhanced ethanol production using hydrophobic resin detoxified two-step pre-treated Pine forest litter hydrolysate, mass balance equation generation and BOLT-ON process development supplementing molasses

Abstract High ethanol demand to make up the targets of the future gradual replacement of gasoline it is essential to look for hybrid technologies using first generation and second-generation biofuel feedstock’s. The current study used a two-step sequential pre-treatment (first dilute alkali, then dilute acid) of Pine (Pinus roxburghii) forest litter (PFL), for bioethanol production. Further, the saccharification of pre-treated PFL was optimized through response surface method using Box–Behnken Design, wherein 0.558 g/g of reducing sugar was under optimized conditions: 12.5% (w/v) of biomass loading, 10 FPU of enzyme, 0.15% (w/v) of Tween-80 in 48 h. During fermentation using Saccharomyces cerevisiae NCIM 3288 strain, the ethanol titre was 22.51 g/L, which was enhanced to 27.38 g/L after detoxification of PFL hydrolysate with hydrophobic resin (XAD-4). Furthermore, the hydrolysate was supplemented with molasses (total initial sugar: 100 g/L), wherein 46.02 ± 2.08 g/L ethanol was produced with 0.482 g/g yield and 1.92 g/l/h productivity. These results, showed that BOLT-ON Technology involving integration of molasses, increases the initial sugar availability leading to enhanced ethanol production, therefore can be compatible in bio-refineries to produce high titer ethanol.