Process Development For Bio-ethanol Production Using Wheat Straw Biomass

PROCESS DEVELOPMENT FOR BIO-ETHANOL PRODUCTION USING WHEAT STRAW BIOMASS Author* HECTOR A. RUIZ Supervisors: José A. Teixeira, António A. Vicente

University of Minho School of Engineering Centre of Biological Engineering

* [email protected]

Methodology

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 environmentalfriendly 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 highervalue 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

Wheat straw

  T − T r l o gR = t⋅e x p O   1 4.7 5

Results and Discussion

35

Hemicellulose 25

H2O Lignin

10 15 20 25 40

15

Oil

10

H+ as catalysts

Cellulose

2 050

Operation conditions for hemicellulose extraction Log Ro T (°C) t (min)

2.76 160 10

3.24 160 30

3.65 180 20

30 195

25 190

Tem p

3.94 200 10

4.42 200 30

Simultaneous saccharification and fermentation process using an experimental design for cellulose+lignin

ENZYME

185

erat

180

u re

20 175

170

(ºC)

15 165

160

10

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: %Y =12.823 +1.567X 2 1

+3.56X

2 2

−1.24X

3

Conclusion

Cellulose-Lignin

BIOETHANOL

Hemicelluloses

2

1

− 2.57X −1.135X 2 −2.582X 3 The maxim yield of ethanol was 80.1 at 45 ºC, 2.5 % of substrate and + 3.784X X + 3.89X X − 2.36X X 1 2 1 3 2 3 17.35 FPU/g of cellulase.

Hydrothermal Treatment

SSF

Tim

n) i m e(

Figure 1. Hemicellulose recovery yield

Milled and Fraction Material

Filtrate

Bioethanol

5

20

YEAST STRAIN

Pellet

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.

30

Yield of Hemicellulose Extraction

Introduction

Full Factor Design 23 Factor Temperature (ºC)

(-1) 30

(0) 37.5

(+1) 45

Substrate (% Cellulose)

2

2.5

3

17.5

30

Enzyme Loading (FPU/ g) 5

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.

Engenharia para a Qualidade de Vida: MOBILIDADE E ENERGIA – Semana da Escola de Engenharia -11 a 16 de Outubro de 2010