Integrated approach for effective bioethanol production using whole slurry from autohydrolyzed Eucalyptus globulus wood at high-solid loadings

Abstract

h i g h l i g h t sIntegrated process optimization was evaluated for 2G bioethanol production. Enzymatic saccharification of whole-slurry from pretreatment was optimized. Two strategies with/without presaccharification to ethanol production were compared. Optimized conditions lead ethanol titer >6% using industrial yeast strain by SSF. Effective bioethanol production from whole slurry E. globulus was achieved. a b s t r a c tOne of the most important targets and challenges in the second generation bioethanol is the development of a cost-effective process on large-scale. In this context, the high solid loading on saccharification and fermentation and the use of whole-slurry from pretreatment could be promising alternatives to obtain high ethanol concentrations and to decrease operational costs and wastewater. In this work, Eucalyptus globulus wood was submitted to non-isothermal autohydrolysis treatment (T max = 210°C) and the whole-slurry obtained was assayed for the optimization of enzymatic saccharification at different solid and enzymes (CTec2 and HTec2) loadings using a Box-Behnken experimental design. Under the optimized conditions (liquid solid ratio 6.4 g/g, cellulase to substrate ratio 22.5 FPU/g and hemicellulase to substrate ratio 500 UI/g), two strategies were evaluated for ethanol production (Simultaneous Saccharification and Fermentation, SSF and Presaccharification and Simultaneous Saccharification and Fermentation, PSSF), using an industrial and robust Saccharomyces cerevisiae strain. High concentrations of ethanol (50.2 and 48.8 g/L) and productivities (0.63 and 0.55 g/L h) were obtained by SSF and PSSF, respectively. The SSF process proved to be an advantageous strategy to obtain concentrations >6% (v/v) of ethanol with elevated conversion (95%) even employing high solid loading and non-detoxified hydrolysate. Following an integrated optimization process, cost-effective bioethanol production conditions from whole-slurry E. globulus wood were determined and validated experimentally, representing a step-forward towards its industrial implementation.

Effect of Cellulase, Substrate Concentrations, and Configuration Processes on Cellulosic Ethanol Production from Pretreated Arundo donax

“…These findings were in agreement with Romaní et al (2014) and Hoyer et al (2009), who reported better performance for SSF than PSSF. The PSSF process significantly increased the % cellulose conversion only when the % cellulose conversion and ethanol concentration were low in the SSF process, but otherwise, it did not have a significant effect, or even had a negative effect when a high cellulose conversion and ethanol content were obtained without a pre-hydrolysis step (Hoyer et al 2013).…”

Production of cellulosic ethanol from steam-exploded Eucalyptus urograndis and sugarcane bagasse at high total solids and low enzyme loadings

“…Romaní et al [32] produced cellulosic ethanol from pretreated substrates that were produced by non-isothermal autohydrolysis of E. globulus chips. In this pretreatment procedure, the reactor vessel was heated up to 210 °C and, when this temperature was reached, the heating system was disabled and the reactor was cooled down to ambient temperature for a total pretreatment time of 50 min.…”

A holistic engineering approach for utilization of olive pomace

“…As for hexane de-oiled olive pomace, the highest reducing sugar concentration was found to be 10.12 g/l obtained with 6 g substrate, Cellic CTec2/Novozyme 188 ratio of 27 for 23 h. Haagensen and coworkers [12] also reported similar reducing sugar concentrations for enzymatic hydrolysis of 100 g/l olive pulp with 100 FPU g −1 (mixture of Celluclast and Novozyme 188) as 10.93 g/l after 7 days of incubation. On the other hand, Sadeghi and coworkes [30] reached 20 g/l sugar concentration after two cycle with 8 h using 100 g substrate per cycle and 40 ml enzyme was loaded which is a significantly high concentration considering the fact that 20% Cellic CTec2/Novozyme 188 ratio used in this study corresponds to 0.1 ml Cellic CTec2 and 0.4 ml of Novozyme 188.…”

“…The biorefinery approach involves the fractionation of various biomasses from agricultural to marine origins and conversion of each fraction to a value-added product. In the case of lignocellulosic biomasses, alkali, acid and enzymatic hydrolyses along with mechanical pretreatments [12,13] last decades and the fact that biomass supplies roundly 11-14% of total world-wide energy demand [14].…”