Title:Response Surface Optimization of the Thermal Acid Pretreatment of Sugar Beet Pulp for Bioethanol Production Using Trichoderma viride and Saccharomyces cerevisiae
Volume: 9
Issue: 1
Author(s): Nour Sh. El-Gendy, Hekmat R. Madian, Hussein N. Nassar and Salem S. Abu Amr
Affiliation:
Keywords:
Acid pretreatment, bioethanol, fungal hydrolysis, sugar beet pulp, Saccharomyces cerevisiae,
Trichoderma viride.
Abstract: Background: Worldwide nowadays, relying on the second generation bioethanol
from the lignocellulosic feedstock is a mandatory aim. However, one of the major drawbacks
for high ethanol yield is the physical and chemical pretreatment of this kind of feedstock.
As the pretreatment is a crucial process operation that modifies the lignocellulosic
structure and enhances its accessibility for the high cost hydrolytic enzymes in an attempt to maximize the
yield of the fermentable sugars. The objective of this work was to optimize and integrate a physicochemical
pretreatment of one of the major agricultural wastes in Egypt; the sugar beet pulp (SBP) and the enzymatic
saccharification of the pretreated SBP using a whole fungal cells with a separate bioethanol fermentation
batch processes to maximize the bioethanol yield. Methods and results: The response surface methodology
was employed in this study to statistically evaluate and optimize the conditions for a thermal acid pretreatment
of SBP. The significance and the interaction effects of the concentrations of HCl and SBP and the reaction
temperature and time were studied using a three-level central composite design of experiments. A quadratic
model equation was obtained to maximize the production of the total reducing sugars. The validity of the
predicted model was confirmed. The thermally acid pretreated SBP was further subjected to a solid state fermentation
batch process using Trichoderma viride F94. The thermal acid pretreatment and fungal hydrolyzes
were integrated with two parallel batch fermentation processes of the produced hydrolyzates using Saccharomyces
cerevisiae Y39, that yielded a total of ≈ 48 g/L bioethanol, at a conversion rate of ≈ 0.32 g bioethanol/
g SBP. Conclusion: Applying the proposed integrated process, approximately 97.5 gallon of ethanol would be
produced from a ton (dry weight) of SBP.