Post on 22-Nov-2014
description
University of Minho School of Engineering Centre of Biological Engineering
Engenharia para a Qualidade de Vida: MOBILIDADE E ENERGIA – Semana da Escola de Engenharia -11 a 16 de Outubro de 2010
Introduction
Bio-ethanol is the most widely produced biofuel in the world with Brazil (from sugar cane) and the US (from corn starch) being the leading producers. To reduce the competition between food and energy industries for these agro-based raw material, there is an urgency to also use the lignocellulosic biomass as additional carbon source for generation of ethanol and other value-added co-products. European Union states have been implementing environmental-friendly methodologies and process in order to develop and optimized bioethanol production from lignocellulosic biomass. Portugal has invested in improving the technology for bioenergies production from alternative agroindustrial residues, instead of using sources that affect world food supply. Wheat production in Portugal was 135,800 tons in 2007 (FAO) being wheat straw an abundant by-product with wide potential to serve as a low-cost raw material for obtaining higher-value industrial products, particularly chemical derivatives from cellulose, hemicelluloses, and lignin.
In this work, the evaluation of process variables (temperature, residence time and particle size) hydrothermal pretreatment of wheat straw and ethanol production was addressed by a factorial design. The recovery of hemicellulose derived sugars (HDS) in the liquid fraction and the ethanol production of the solid residue obtained after filtration of pretreated material were considered as response variables to different processes conditions.
Methodology
Author* HECTOR A. RUIZ
Supervisors: José A. Teixeira, António A. Vicente
* hector_ruiz@deb.uminho.pt
PROCESS DEVELOPMENT FOR BIO-ETHANOL PRODUCTION USING WHEAT STRAW BIOMASS
Methodology
Operation conditions for hemicellulose extraction
Simultaneous saccharification and fermentation process using an experimental design for cellulose+lignin
Results and Discussion
Simultaneous saccharification and fermentation
A central point experimental design was performed with different combinations of the variables that were selected shows the experimental data and the values predicted by the model constructed using the final ethanol titre as the response variable. By applying multiple regression analysis on the experimental data, the following second-order polynomial equation giving the ethanol (Y) as a function of Temperature ºC (X1), Substrate % (X2) and loading enzyme (X3) was obtained:
The maxim yield of ethanol was 80.1 at 45 ºC, 2.5 % of substrate and 17.35 FPU/g of cellulase.
Conclusion
This study examined a hydrothermal treatment (autohydrolysis) could be an adequate process for the fractionation of lignocellulosic materials.
The present investigation also show that the hydrothermal treatment consequently improved ethanol production during SSF processing since the ethanol concentration was 80.1 % respect of the theoretical ethanol yield.
Wheat straw Milled and Fraction Material
Hemicelluloses
Hydrothermal Treatment
Filtrate
Cellulose-Lignin
Pellet
SSF
Bioethanol
logRO t expT Tr14.75
Log Ro 2.76 3.24 3.65 3.94 4.42T (°C) 160 160 180 200 200 t (min) 10 30 20 10 30
YEAST STRAIN ENZYME
BIOETHANOL
Lignin
Cellulose
Hemicellulose
H2O
H+ as catalysts
Oil
Full Factor Design 23
Factor (-1) (0) (+1)
Temperature (ºC) 30 37.5 45
Substrate (% Cellulose) 2 2.5 3Enzyme Loading (FPU/ g) 5 17.5 30
5
10
15
20
25
30
35
10
15
20
25
30
160165
170175
180185
190195
200
5 10 15 20 25 40
Temperature (ºC)Time (m
in)
Yie
ld o
f H
emic
ellu
los
e E
xtr
act
ion
Figure 1. Hemicellulose recovery yield
In the hemicellulose extraction (Fig.1) the highest recovery were at 200°C/30 min and 180°C/20 min with yields values of 31 and 28%, respectively.
%Y 12.823 1.567X1 3.56X2 1.24X3
2.57X12 1.135X2
2 2.582X32
3.784X1X2 3.89X1X3 2.36X2X3