Comparison of Feedstock Pretreatment Performance and Its Effect on Soluble Sugar Availability

Abstract

Cellulosic feedstocks for bioenergy differ in composition and processing requirements for efficient conversion to chemicals and fuels. This study discusses and compares the processing requirements for three lignocellulosic feedstocks-soybean hulls, wheat straw, and de-starched wheat bran. They were ground with a hammer mill to investigate how differences in composition and particle size affect the hydrolysis process. Enzyme hydrolysis was conducted using cellulase from Trichoderma reesei at 50°C and pH 5. Ground fractions were also subjected to dilute sulfuric acid treatment at 125°C, 15 psi for 30 min prior to cellulase treatment. Reducing particle size of biomass resulted in segregated components of feedstock. Grinding wheat straw to particle size <132 μm resulted in measured lignin content from 20% to ≈5% and reduced hemicellulose content. Reducing lignin content increased the effectiveness of enzyme hydrolysis of wheat straw. Particles sized <132 μm exhibited the highest soluble sugar release upon hydrolysis for all three feedstocks studied. Hemicellulose digestion improved with dilute sulfuric acid treatment with residual hemicellulose content <5% in all three feedstocks after acid treatment. This enhanced the cellulase action and resulted in approximately 1.6-fold increase in sugar availability in de-starched wheat bran and ≈1.5-fold for wheat straw and soybean hulls. Higher sugar availability in wheat bran after acid-mediated enzyme treatment correlated to higher ethanol yields during yeast fermentation compared with soybean hulls and wheat straw.

THE EFFECTIVENESS OF PHYSICAL AND ALKALI HYDROTHERMAL PRETREATMENT <br> IN IMPROVING ENZYME SUSCEPTIBILITY OF SWEET SORGHUM BAGASSE

“…Analysis of variance (p = 0.05) showed that particle size did not have significant effect on the lignin content. This is consistent with the results of a study conducted by Lamsal & Madl (2011) that found that differences in particle sizes had not have significant effect on lignin content of wheat straw, wheat hull and soybean. On the other hand, the results of analysis of variance (p = 0.05) showed a significant effect of washing treatment on lignin content.…”

“…This made the hydrolysis process was running more intensively. This result was similar with the results reported by Lamsal & Madl (2011) who found that there was a correlation between particle size reduction and the increase of reducing sugars in soybean hulls, even though the higher cellulose content was in the biomass with larger particel size.…”

Celluclast and Cellic® CTec2: Saccharification/fermentation of wheat straw, solid–liquid partition and potential of enzyme recycling by alkaline washing

“…Although a significant effort has been made to improve the pretreatment step, an efficient enzymatic hydrolysis still requires high enzyme loadings which contribute to the high costs of the biomass-derived ethanol [1,2]. Researchers attempted to reduce the cost of enzymatic hydrolysis [3,4] by (i) minimizing the costs of enzyme production, (ii) increasing the enzymes specific activity, (iii) reducing the required cellulase loading by pretreating the biomass [5], (iv) or recycling the enzymes for multiple rounds of hydrolysis [2,4,[6][7][8][9][10][11][12][13].…”

Reviews of Science for Science Librarians: Microbes that Make Biofuels and Work within Fuel Cells

“…This speeds its saccharification for subsequent bioethanol production by Saccharomyces cerevisae or other synergistic microbes (Garvey et al 2013). Sometimes used in concert with other heator chemical-based pretreatments (Lamsal, Madl, and Tasakpunidis 2011), Trichoderma reesei inoculation or enzyme injection has had successes against a very wide array of some of the world's most important bulky and saccharification-resistant agricultural wastes (Sarkar, Ghosh, and Bannerjee 2012), including corn stover (Minty et al 2013), wheat straw (Xin, Zhang, Downloaded by [University of Colorado -Health Science Library] at 10:52 14 October 2014 and Wong 2013), soybean straw (Xu et al 2007), rice straw and rice bran (Das et al 2013), wheat bran, and soybean hulls (Banerjee et al 2010). It has shown great promise in pretreatment of what is arguably the most-talkedabout energy crop today: switchgrass (Cianchetta et al 2012).…”