Pretreatment
Pre-treatment is a prerequisite for disintegrating the complex nature of lignocellulose to a substrate, which is comparatively easily accessible to enzymes and microbes for subsequent bioconversion to ethanol (Gregg and Saddler, 1996). We have been mainly focussing on two major pre-treatment processes; steam pre-treatment and Organosolv pre-treatment. These two pre-treatment processes are recognized as the potential pre-treatment processes for the production of bioethanol due to its numerous technical, economic and environmental advantages (Saddler et al, 1993; Ramos et al 1992). The steam pre-treatment process consists of subjecting the feedstock to high-pressure steam at temperatures normally in the range of 170-240ºC for retention times ranging from a few seconds to a few minutes concluding with a final pressure release that facilitates the disintegration of the feedstock (Chandra et al, 2007). Organosolv pre-treatment uses an organic solvent at high temperature and pressure to disintegrate the structure of lignocellulose. This treatment essentially leads to the partial removal of lignin and hemicellulose thereby increasing the enzyme accessibility to the substrate. See our pretreatment facilities.
In pre-treatment research, our goal continues to develop and optimise the pre-treatment processes which lead to maximum ethanol production with least chemical and enzyme inputs. We are in the process of elucidating various factors, which affects the efficiency of the pre-treatment. We also continue our efforts in examining the physical and chemical reaction changes occurring during pre-treatment and their consequent effect on enzyme hydrolysis and fermentation.
Our partners in pre-treatment research: Novozymes, NSERC, Forintek, Weyerhaeuser Canada, NRCAN
Selected Pretreatment Publications:
Panagiotopoulos, I.A., Chandra, R.P., Saddler, J.N. 2013. A two stage pretreatment approach to maximise sugar yield to enhance reactive lignin recovery from poplar wood chips. Bioresource Technology (2013), 130, 570–577. http://dx.doi.org/10.1016/j.biortech.2012.12.093
Saddler, J.N., Kumar, L. 2013. Special Issue from the NSERC Bioconversion network workshop: pretreatment and fractionation of biomass for biorefinery/biofuels. Biotechnology for Biofuels 2013, 6:17. http://dx.doi.org/10.1186/1754-6834-6-17
Kumar, L., Tooyserkani, Z., Sokhansanj, S., Saddler, J.N. 2012. Does densification influence the steam pretreatment and enzymatic hydrolysis of softwoods to sugars? Bioresource Technology (2012), 6:15, 121, 190-198. http://dx.doi.org/10.1016/j.biortech.2012.06.049
Kumar, L., Chandra, R., Saddler, J. 2011. Influence of Steam Pretreatment Severity on Post-Treatments Used to Enhance the Enzymatic Hydrolysis of Pretreated Softwoods at Low Enzyme Loadings. Biotechnology and Bioengineering, 108(10), 2300-2311. http://dx.doi.org/10.1002/bit.23185
Nakagame, S., Chandra, R.P., Kadla, J.F., Saddler, J.N. 2011a. Enhancing the Enzymatic Hydrolysis of Lignocellulosic Biomass by Increasing the Carboxylic Acid Content of the Associated Lignin. Biotechnology and Bioengineering, 108(3), 538-548. http://dx.doi.org/10.1002/bit.22981
Nakagame, S., Chandra, R.P., Kadla, J.F., Saddler, J.N. 2011b. The isolation, characterization and effect of lignin isolated from steam pretreated Douglas-fir on the enzymatic hydrolysis of cellulose. Bioresource Technology, 102(6), 4507-4517. http://dx.doi.org/10.1016/j.biortech.2010.12.082
Chandra, R.P., Au-Yeung, K., Chanis, C., Roos, A.A., Mabee, W., Chung, P.A., Ghatora, S., Saddler, J.N. 2011. The Influence of Pretreatment and Enzyme Loading on the Effectiveness of Batch and Fed-Batch Hydrolysis of Corn Stover. Biotechnology Progress, 27(1), 77-85. http://dx.doi.org/10.1002/btpr.508
Shen, F., Kumar, L., Hu, J., Saddler, J.N. 2011. Evaluation of hemicellulose removal by xylanase and delignification on SHF and SSF for bioethanol production with steam-pretreated substrates. Bioresource Technology, 102(19), 8945-8951. http://dx.doi.org/10.1016/j.biortech.2011.07.028
Shen, F., Saddler, J.N., Liu, R., Lin, L., Deng, S., Zhang, Y., Yang, G., Xiao, H., Li, Y. 2011. Evaluation of steam pretreatment on sweet sorghum bagasse for enzymatic hydrolysis and bioethanol production. Carbohydrate Polymers, 86(4), 1542-1548. http://dx.doi.org/10.1016/j.carbpol.2011.06.059
Kumar, L., Chandra, R., Chung, P.A., Saddler, J. 2010. Can the same steam pretreatment conditions be used for most softwood to achieve good, enzymatic hydrolysis and sugar yields? Bioresource Technology, 101(20), 7827-7833. http://dx.doi.org/10.1016/j.biortech.2010.05.023
Del Rio, L.F., Chandra, R.P., Saddler, J.N. 2010. The effect of varying organosolv pretreatment chemicals on the physicochemical properties and cellulolytic hydrolysis of mountain pine beetle-killed Lodgepole pine. Applied Biochemistry and Biotechnology, 161(1-8), 1-21. http://dx.doi.org/10.1007/s12010-009-8786-6
Pan, X., Xie, D., Yu, R.W., Lam, D., Saddler, J.N. 2007. Pretreatment of lodgepole pine killed by mountain pine beetle using the ethanol organosolv process: Fractionation and process optimization. Industrial & Engineering Chemistry Research, 46(8), 2609-2617. http://dx.doi.org/10.1021/ie061576l
Chandra, R.P., Saddler, J.N., Beatson, R.P. 2007. Treatment of Douglas-fir heartwood thermomechanical pulp with laccases: Effect of treatment conditions on peroxide bleaching. Journal of Wood Chemistry and Technology, 27(2), 73-82. http://dx.doi.org/10.1080/02773810701486709