Title
Bioethanol production from cellulosic fibers: comparison between batch and fed-batch saccharification
Authors
CÁTIA V. T. MENDES M. GRAÇA V. S. CARVALHO and JORGE M. S. ROCHA

Received October 7, 2015
Published Volume 51 Issue 3-4 March-April
Keywords cellulosic fibers, SHF, bioethanol, batch, fed-batch

Abstract
Unbleached pulp from the pulp and paper industry was used as a cellulosic material source to produce bioethanol in a separate hydrolysis and fermentation process. In the batch enzymatic saccharification, three cellulolytic enzymes and different initial carbohydrate (CH) contents were tested. Cellic® CTec2 was shown to be the most efficient enzyme with the lowest dosage used: 35 FPU gCH-1. Sugar production increased when the initial carbohydrate content increased from 58 to 116 g L-1, while the hydrolysis efficiency decreased. Enzymatic hydrolyzates from the batch and fed-batch operations were further used in ethanolic fermentation with Saccharomyces cerevisiae ATCC 26602. An ethanol concentration of up to 28 g L-1 was achieved from 80 g L-1 of reducing sugars. A sugar-to-ethanol conversion of up to 69% and an ethanol productivity of 0.39 g L-1 h-1 were obtained with batch hydrolyzates. Nevertheless, the fed-batch mode led to higher bioethanol production per gram of carbohydrate and per enzyme unit.