As a potential alternative to fossil-based fuels, cellulosic ethanol has attracted much attention due to its great benefit to energy sustainability and environmental friendliness. However, at present, the industrial competitiveness of cellulosic ethanol production is still insufficient compared with fossil-based fuels because of the higher costs. Expanding the range of lignocellulosic biomass may be a promising measure to promote the economical production of cellulosic ethanol. Corn fiber, a byproduct from the corn deep-processing, is an attractive feedstock for cellulosic ethanol production because of its rich carbohydrate content (generally exceeding 65% of dry weight), almost no transportation cost, and low lignin content allow it to be easily handled. This study first optimized the hydrolysis conditions, including the pretreatment and enzymolysis process based on dilute sulfuric acid, to achieve a high sugar yield. Then, the corn fiber hydrolysates obtained under different hydrolysis conditions were suitably fermented by different C5/C6 co-fermentation Saccharomyces cerevisiae, indicating that the hydrolysate at high solid loading (20%) needs to detoxification to a certain extent but not low solid loading (10%) to achieve high ethanol yield. Finally, the fermentation of the 20% solid loading hydrolysates with resin detoxification was performed in a 50 L bioreactor, achieving the sugar (glucose and xylose) metabolic rate of 2.24 g L ⁻¹ h ⁻¹ and ethanol yield of 92% of the theoretical value, which are the highest reported levels to date. This study provided a potential process route for cellulosic ethanol production from corn fiber from the perspective of the suitability between the upstream hydrolysis process and the downstream fermentation strain.

Cellulosic ethanol is the key technology to alleviate the pressure of energy supply and climate change. However, the ethanol production process, which is close to industrial production and has a high saccharification rate and ethanol yield, still needs to be developed. This study demonstrates the effective conversion of poplar wood waste into fuel-grade ethanol. By employing a two-step pretreatment using sodium chlorite (SC)-dilute sulfuric acid (DSA), the raw material achieved a sugar conversion rate exceeding 85% of the theoretical value. Under optimized conditions, brewing yeast co-utilizing C6/C5 enabled a yield of 35 g/L ethanol from 10% solid loading delignified poplar hydrolysate. We increased the solid loading to enhance the final ethanol concentration and optimized both the hydrolysis and fermentation stages. With 20% solid loading delignified poplar hydrolysate, the final ethanol concentration reached 60 g/L, a 71.4% increase from the 10% solid loading. Our work incorporates the pretreatment, enzymatic hydrolysis, and fermentation stages to establish a simple, crude poplar waste fuel ethanol process, expanding the range of feedstocks for second-generation fuel ethanol production.