Box–Behnken Design-Based Optimization of the Saccharification of Primary Paper-Mill Sludge as a Renewable Raw Material for Bioethanol Production

In this study, the primary paper-mill sludge characterized as containing 51% glucan was used to optimize enzymatic saccharification process for production of bioethanol using a Box–Behnken design (BBD). Polyethylene glycol 4000 (PEG-4000) surfactant-assisted dried (DPS) showed 12.8% improvement in efficiency. There statistically significant effect solid enzyme loading and time on DPS at 95% confidence level (p < 0.05). The optimum levels 10.4% w/w loading, 2.03% (10 FPU g/DPS), 1% (w/w DPS) PEG-4000 efficiency 57.66% were validated experimentally found be non-significant with regard lack fit predicted 56.76%. Furthermore, Saccharomyces cerevisiae fermented saccharified sugars into ethanol (9.35 g/L) sugar-to-ethanol conversion yield 91.6% compared theoretical maximum. Therefore, is more suitable renewable biomass determining presence fermentable sugar ethanol.