Recycling Of Cellulases During Ligno-cellulose Ethanol Production Process By Simultaneous Saccharification And Fermentation

Corncob residues were the industrial byproducts during xylose or xylitol production process, in which the most hemicellulose was extracted. Due to the high cellulose content, low hemicellulose and no need to conduct energy-intensive pretreatment, corncob residues were considered a suitable substrate for ethanol and other high value-added chemical production. However, the cellulase cost accounted for nearly half of the cellulosic ethanol production cost during simultaneous saccharification and fermentation (SSF) of lignocellulose. The objective of this study was to recycle the cellulase and further decrease the cellulase dosage through intermittent vacuum distillation for ethanol separation and fresh substrate feeding during SSF of corncob residues. The results showed that when the cellulase dosage was decreased from15FPU/g DM to10FPU/g DM through intermittent vacuum distillation and fresh substrate feeding, the final ethanol yield based on the theoretical ethanol production reached83.69%, which was19.72%higher than that conducted in the batch SSF at10FPU/g DM. and could compete for that conducted in the batch SSF at15FPU/g DM (ethanol yield was89.56). This study provided a practical method for in-situ ethanol separation, ethanol condensation, cellulase and yeast cells recycling for efficient cellulosic ethanol production using ligno-cellulosic feedstock, which may be helpful for significantly reducing the cellulosic ethanol production cost.In addition, this study also investigated and developed a simple and efficient solids/liquid separation method for high concentration cellulosic lactic acid fermentation slurry. The chitosan was added into the lactic acid slurry to reach0.74g/L, then adjusted the pH value to5.5and mixed intensively for10seconds at20-30℃. After that the mixture was filtered under vacuum condition for15-25minutes and the clear lactic acid liquid without solid residues was obtained, in which the lactic acid recovery could reach64.48-68.68%. This solids/liquid separation method was a useful technique reservoir for the large scale cellulosic lactic acid industrially production.