Hemicellulosic Ethanol Production in Fluidized Bed Reactor from Sugar Cane Bagasse Hydrolysate: Interplay among Carrier Concentration and Aeration Rate

摘要

Development of an efficient consolidated process is pivotal in order to design industrially viable processes for conversion of lignocellulosic biomass into second generation (2G) ethanol. Aiming to develop process consolidation, here we explored fluidized bed reactor (FBR) for 2G ethanol production from sugar cane bagasse hemicellulosic hydrolysate (SBHH) employing calcium alginate immobilized cells of Scheffersomyces shehatae UFMG-HM 52.2. A 2(2)-full factorial design of experiments was carried out in order to evaluate the effect of aeration rate (0.027, 0.069, and 0.111 min(-1)) and carrier concentration (55.55, 83.33, and 111.11 g. L-1) on the ethanol yield (Y-P/S) and productivity (Q(p)). Both process variables, when used at the highest level (aeration, 0.11 min(-1); immobilized carrier concentration, 111.11 g. L-1), showed maximum ethanol production (Y-P/S, 0.26 g/g and Q(p), 0.17 g.L-1.h(-1)). Results showed the potential to use this immobilized yeast in a fluidized bed reactor for ethanol production from C5 sugar solution. Repeated batch fermentations in FBR showed stable ethanol yield during 6 batches (288 h) followed by a gradual decrease. The use of immobilized cells in FBR could be conducive to the development of viable 2G ethanol production processes. To the best of our knowledge, this is the first report on 2G ethanol production from immobilized S. shehatae cells employing FBR using SBHH.