Ethanol production from sugarcane bagasse by fed-batch simultaneous saccharification and fermentation at high solids loading

To make the bioethanol conversion process economically viable, improving solids loading (>15% [w/v]) in different unit operations is crucial. In this study, alkali pretreatment of sugarcane bagasse was carried out at high solids loading. Temperature and pH were optimised via batch simultaneous saccharification and fermentation (SSF) experiments using Saccharomyces cerevisiae Y-2034 or Kluyveromyces marxianus NCYC-587. The effects of enzyme addition mode and solids loading on ethanol production were studied in fed-batch SSF experiments. It was demonstrated that the optimised pH and temperature for both S. cerevisiae Y-2034 and K. marxianus NCYC-587 were 5.2 and 37 degrees C. The mode of enzyme addition "one-time dose" improved ethanol productivity better than the "batch addition" mode. With fresh substrates added, solids loading strongly increased from 19% to 33% (w/v), corresponded to a small decline in the ethanol yield. At the final solids loading of 33% (w/v), the highest ethanol concentration of 75.57 +/- 2.14 g/L was obtained, with ethanol productivity of 0.63 +/- 0.02 g/(L h) and a yield of 66.17 +/- 1.87%