Source: UNIVERSITY OF WASHINGTON submitted to NRP
EVALUATION OF CRUMBLES FEEDSTOCKS FOR BIOCONVERSION PROCESSES
Sponsoring Institution
Other Cooperating Institutions
Project Status
COMPLETE
Funding Source
STATE
Reporting Frequency
Annual
Accession No.
0224734
Grant No.
(N/A)
Cumulative Award Amt.
(N/A)
Proposal No.
(N/A)
Multistate No.
(N/A)
Project Start Date
Aug 15, 2010
Project End Date
Aug 14, 2013
Grant Year
(N/A)
Program Code
[(N/A)]- (N/A)
Recipient Organization
UNIVERSITY OF WASHINGTON
4333 BROOKLYN AVE NE
SEATTLE,WA 98195
Performing Department
Bioresource Science and Engineering
Non Technical Summary
The goal of these experiments will be to find pretreatment conditions that result in good solid phase enzymatic hydrolysis without the formation of excessive fermentation inhibitors. It should be noted that a reduction in pretreatment severity could be one of the benefits of using Forest Concepts precision feedstock. Results of this optimization work will demonstrate the reduction in pretreatment energy intensity that can be achieved with the new feedstock particle size and physical properties. An additional potential benefit of the steam explosion/enzymatic pretreatment process is that the biomass must be fresh processed and maintained at high moisture content from the harvest to conversion. This may substantially reduce the total energy requirements for woody biomass fed biorefineries that are close-coupled to energy plantations or ongoing forest operations. We will update an existing Aspen biorefinery model to include our novel unit operations and equipment. Outputs from the models will be used to calculate processing energy and material demands as well as process economics. These results will provide a definitive measure of the environmental and economic performance associated with use of Crumbles feedstock in comparison to when traditional chips are used as raw material sources.
Animal Health Component
(N/A)
Research Effort Categories
Basic
(N/A)
Applied
(N/A)
Developmental
(N/A)
Classification

Knowledge Area (KA)Subject of Investigation (SOI)Field of Science (FOS)Percent
4030680200050%
4030680208050%
Knowledge Area
403 - Waste Disposal, Recycling, and Reuse;

Subject Of Investigation
0680 - Other products of the forest;

Field Of Science
2080 - Mathematics and computer sciences; 2000 - Chemistry;
Goals / Objectives
Researchers at the University of Washington will explore the potential benefits of rotary sheared Crumbles wood particles for pretreatment. We are particularly interested in the possibility that the uniformly sized and sheared particles may be able to be processed at much shorter steam explosion times than are wood chips. The goal of these experiments will be to find pretreatment conditions that result in good solid phase enzymatic hydrolysis without the formation of excessive fermentation inhibitors. In addition, we will update our Aspen biorefinery model to include our novel unit operations and equipment.
Project Methods
1. Perform biochemical conversion experiments with two Forest Concepts provided feedstocks: Fresh poplar and pine wood will be comminuted by the rotary shearing process such that they are screened on No.4 - No. 10 screens. To serve as controls, conventionally produced pine and poplar chips will be pretreated. In initial experiments, the poplar feedstock will be steam exploded at 190 degrees C, with 5 minutes of reaction time, and 3% addition of SO2. The pine feedstock will be steam exploded at 200 degrees C, with 5 minutes of reaction time, and 4% addition of SO2. The steam explosion pretreatment will fractionate the biomass into a solid phase and a liquid phase. The composition of the solid and liquid phases following pretreatment will be thoroughly characterized. Enzymatic hydrolysis experiments will be carried out on the solid phase following pretreatment to determine if the conditions were sufficiently severe to open the biomass structure. Each of the solid phase samples will be hydrolyzed with the same conditions. Sugar analysis results will be used to calculate the rate of enzymatic hydrolysis and extent of hydrolysis for each of the pretreated samples. The relationships between the initial biomass particle size and morphology, and the efficacy of steam explosion pretreatment may then be established. It is anticipated that the pretreatment conditions acceptable for chips will be too severe for the smaller sheared Crumbles particle biomass. If we find the initial steam pretreatment conditions are too severe for the small particle size samples, we will repeat the experiments but with less severe conditions. 2. Adapt existing Aspen biorefinery model for one species to include our novel unit operations and equipment: The University of Washington has developed a detailed Aspen model of a biorefinery producing ethanol using bioconversion technology. Steam explosion pretreatment research will provide data to develop the model. Current Life Cycle Assessment research supported by the United States Forest Service and Department of Energy will result in an even more robust and sophisticated biorefinery models that may be adapted for this project. In addition to the material and energy balance models, we will have developed financial spreadsheets that are linked to Aspen models to calculate the economic performance of any bioconversion scenario that we envision. We will use the results of the experimental work from this research to derive bioconversion models that are appropriate for the Crumbles feedstock. These models will include modules for the wood processing unit operations as well as modifications to the biorefinery processing conditions that the Crumbles wood feedstock material enables. Outputs from the models will be used to calculate processing energy and material demands as well as process economics. These results will provide a definitive measure of the environmental and economic performance associated with use of Crumbles feedstock in comparison to when traditional chips are used as raw material sources.

Progress 08/15/10 to 08/14/13

Outputs
Target Audience:Target audiences include Forest Concepts, LLC; biorefiners; researchers; educators; students; and the general public. Changes/Problems: Nothing Reported What opportunities for training and professional development has the project provided?Graduate students Rodrigo Morales-Vera and Chang Dou studied the influence of initial particle size on sugar recovery after steam explosion pretreatment and enzymatic hydrolysis. Rodrigo presented a poster at the AIChE Annual Meeting in 2013, and co-wrote a paper detailing the results, published in Biomass and Bioenergy in 2016. Undergraduate researcher Kelsey Lewis was supported through the Washington Space Grant Consortium's Summer Undergraduate Research Program (SURP). As part of this program, she learned techniques to optimize acetic acid production during conversion of hybrid poplar to jet fuel by using Raman Spectroscopy. How have the results been disseminated to communities of interest?Poster presentation at the AIChE Annual Meeting in November 2013. See products for citation and link to abstract. What do you plan to do during the next reporting period to accomplish the goals? Nothing Reported

Impacts
What was accomplished under these goals? In this research, chemical and physical properties of solids after steam explosion, enzymatic hydrolysability of solids and overall sugar recovery were analyzed. Fresh 18-year-old hybrid poplar, Populus deltoides x Populus nigra, was processed into six different particles sizes: S1 (0.2 x 0.2 cm), S2 (0.4 x 0.4 cm), S3 (0.4 x 1.2 cm), S4 (0.7 x 0.4 cm), S5 (1.0 x 2.0 cm) and S6 (equal mixture of all the particles). Hybrid poplar particles were impregnated with SO2 (3% w/w) and steam pretreated at 195°C for 5 minutes. The steam pretreated particles were then chemically and physically characterized, saccharified at 5% (w/v) solids consistency, 5 FPU/g cellulose, and finally a complete mass balance of carbohydrates was determined. In order to find statistical differences among the different groups of particles, one way ANOVA at 5% alpha was performed for each dependent variable: chemical and physical characteristics of steam pretreated solids, enzymatic digestibility (glucan to glucose conversion) and total sugar recovery after pretreatment and enzymatic hydrolysis. In the cases where statistical differences were found (p value<0.05) a multiple comparison of means "Tukey test" was performed to find the specific group or groups of particles that were causing those differences. The results of the analysis, have shown similar chemical composition of solids after pretreatment for all the particle sizes tested, where the glucan and lignin content ranged from 61 to 65% from and 32 to 36%, respectively. No statistically significant differences were found for both glucan and lignin content for all the particles tested. However, there were statistically significant differences in fiber length and width, where sizes 1, 2 and 3 were shorter and thicker, whereas sizes 4 and 5 were longer and thinner. However, these fiber characteristics did not affect the enzymatic hydrolysis of the solids, since similar cellulose to glucose conversion of 78 to 82% were observed during 72 hours of enzymatic hydrolysis for all the particle sizes. No statistically significant differences in cellulose to glucose conversion were found at 5% alpha level for all the particles tested. In addition, there were not found any statistically significant differences in glucose and xylose recovery after steam pretreatment and enzymatic hydrolysis among the particle sizes investigated. The glucose and xylose recoveries were from 85 to 94% and from 57 to 68%, respectively. Thus, particle size did not influence the overall sugar recovery after pretreatment and enzymatic hydrolysis. This research confirms that steam pretreatment with SO2 as a catalyst is a robust method that can accommodate particles ranging from 0.2 x 0.2 cm to 1.0 x 2.0 cm without altering downstream bioconversion processes.

Publications

  • Type: Journal Articles Status: Published Year Published: 2016 Citation: Morales-Vera, R., Bura, R., and Gustafson, R. 2016. Handling heterogeneous hybrid poplar particle sizes for sugar production. Biomass and Bioenergy 91(2016) 126-133. Available online at: http://dx.doi.org/10.1016/j.biombioe.2016.05.016
  • Type: Conference Papers and Presentations Status: Published Year Published: 2013 Citation: Morales-Vera, R., Bura, R., Gustafson, R., and Dooley, J. 2013. The influence of particle size on bioconversion of hybrid poplar for sugar production. 2013 AIChE (American Institute of Chemical Engineers) Annual Meeting, Poster presented on November 8, 2013. Abstract available online at: https://aiche.confex.com/aiche/2013/webprogram/Paper328457.html