Progress 09/01/13 to 08/31/16
Outputs
Target Audience:Corn-based ethanol plants; soy processing plants; research scientists and engineers Changes/Problems:
Nothing Reported
What opportunities for training and professional development has the project provided?This project has offered the opportunity for the graduate students involved to learn new process simulation tools (such as SuperPro Designer), and they have been able to present their results at professional conferences. This information has also been shared among the research team in monthly project update meetings. How have the results been disseminated to communities of interest?Results were presented at the 2016 annual American Society of Agricultural and Biological Engineers conference (multiple papers and posters). One manuscript has been submitted for publication in Bioresource Technology (currently under review). All other papers which have been presented at conferences are being revised into manuscripts which will be submitted to journals for publication. What do you plan to do during the next reporting period to accomplish the goals?
Nothing Reported
Impacts
What was accomplished under these goals?
The corn ethanol industry has grown exponentially over the last decade. At this point in time, due to unfavorable economic conditions,many ethanol plants struggle financially. Implementingnovel processes could help improve both ethanol production and economics. We have used mathematical modeling tools to understand how to integrate soybean processing into corn ethanol plants, which will result in corn/soy biorefineries. We found that that it is possible to integrate soybean processing into corn ethanol plants in a way that can increase ethanol plant revenue by up to 14% per year. These optimum processes are described below. Objective 1)Determine how best to fully utilize the soybean cotyledon fiber fraction (EAEP soy insolubles) to enhance dry-grind corn ethanol production. Soy insoluble fiber(IF) was treated prior tocorn fermentation, then subjected to simultaneous saccharification and fermentation with soy fiber hydrolyzing enzymes and yeast,as well as fermentation withEscherichia coliKO11. Addition of treated IF in corn fermentation significantly increased ethanol production rate (from 1.0 ± 0.02 to 2.1 ± 0.3 g ethanol/100 g corn/h) and ethanol yield (from 36.6 ± 0.2 to 42.0 ± 1.0 g ethanol/100 g corn/h) compared to corn-only fermentation.In order to implement this in an actual plant, we found thatcorn-to-untreated insoluble fiber ratio of 1:0.16, and water-to-solids ratio of 4.1:1 should be used in the fermenters. Enzyme-assisted Aqueous Extraction Processin (EAEP) was used to separate soy IF and soy skim. After EAEP, soy skim and IF were separated by centrifugation it was then added tocorn fermentation. When only soy skim was added[corn + skim], a significant increase in ethanol production rate (from 1.0 ± 0.02 to 2.3 ± 0.02 g ethanol/100 g corn/h) and ethanol yield (approximately 2% increase) compared to corn-only fermentation was observed. The increase in production rate reduced fermentation time from 68 h to 40 h. When only soy IF was added to corn fermentation [corn + untreated IF], a significant increase in ethanol production rate (1.8 ± 0.1 g ethanol/100 g corn/h) was observed compared to [corn only] (1.0 ± 0.3 g ethanol/100 g corn/h) fermentation. Objective 2) Determine how best to fully utilize the EAEP skim (from the optimum EAEP production strategy) for oil recovery and subsequent acceleration of fuel ethanol fermentation and feed quality improvement. We then conducted experiments to test the effect of adding enzymes when soy skim is used in fermentation. Ethanol production rate significantly increased with the addition of soy skim. Addition of enzymes during corn-soy fermentation significantly increased ethanol yield to a maximum yield of 42.3 g ethanol/g dry corn. Results show that co-fermentation resulted in more oil partitioning in thin stillage than in wet cake. Corn-soy co-fermentation, without enzyme or heating, had 62% oil in the thin stillage. Oil partitioning in thin stillage of co-fermentation was increased to 70% using enzymes. Objective 3) Using experimental data, build advanced mathematical models to conduct techno-economic analyses (TEA) and life-cycle assessments (LCA) for various strategies of integrating soybean EAEP into a dry-grind corn ethanol plant, in order to identify the most profitable approach with minimum environmental impacts. SuperPro Designer software was used to build techno-economic analysis (TEA) and environmental impact analysis (EIA) models for cost and environmental analyses.The TEA model for the EAEP process was built, based on data from pilot-scale processing at Iowa State University. Fixed costs, operating costs (including all material, utility and labor costs) were considered. Several scales were also investigated. A scale of 75 kg/hr had the highest production cost, 23.3 $/(kg soybean oil). As scale increased, production costs decreased, and the largest scale (51 million kg/yr soybean oil) had the lowest production cost, 3.43 $/(kg soybean oil). When the unit production cost falls below 4 $/(kg soybean oil), EAEP processing becomes profitable. For environmental analysis, EAEP was compared to traditional expelling and hexane extraction. EAEP had an overall environmental impact similar to expelling due to water use (as the solvent for extraction). Because EAEP could have higher oil recovery than expelling, it did have an improved environmental footprint compared to solvent extraction. However, a large amount of water usage is a potential challenge. Total GHG emissions were estimated combining the TEA and GREET models.We determined that EAEP had the highest total GHG emissions (1.83 kg CO2-equiv./kg soybean oil) compared to 0.73 and 0.56 CO2-equiv./kg soybean oil for expelling and hexane extraction, respectively. This occurred because considerable pretreatments are needed for EAEP (to produce finer soybean flakes in order to have higher surface area for oil recovery). Pretreatments include cracking, milling, and extruding; all have high energy consumption.Therefore, from the perspective of energy consumption and GHG emissions, EAEP has a worse environmental footprint. Using data from Objectives 1 and 2 (corn-to-untreated insoluble fiber ratio of 1:0.16, and water-to-solid ratio of 4.1:1 in the fermenters), we then analyzed an integrated corn-soy biorefinery, where the EAEP process was combined with a traditional corn ethanol plant (including all support systems, coproduct processing, ethanol processing, fermentation, starch to sugar conversion, and grain handling and milling).Again, TEA and EIA were conducted to understand cost and environmental impacts.The ethanol plant was designed to consume 370 million kg corn per year, and included 389.0 million kg untreated insoluble fiber (UIF) and 165.4 million kg soy skim from the EAEP soybean process. By integrating EAEP into a corn ethanol plant, we found a 3.9% increase in ethanol yield and a 6.1% increase in DDGS yield. In addition, oil from DDGS extraction increased from 3.22 to 4.19 thousand tons per year (30% increase). Revenues also increased to $135 million/yr (compared to $118 million/yr) (a 14% increase). Revenue per unit production increased from $0.99 to $1.03 / 1 kg ethanol.
Publications
- Type:
Conference Papers and Presentations
Status:
Published
Year Published:
2016
Citation:
Ming-Hsun Cheng, Weitao Zhang, Kurt A. Rosentrater, Jasreen J.K. Sekhon, Tong Wang, Stephanie Jung, Lawrence A. Johnson. 2016. Environmental Impact Analysis of Soybean Oil Production from Expelling, Hexane Extraction and Enzyme Assisted Aqueous Extraction. ASABE 2016 Annual Meeting, Orlando, FL, July, 2016.
- Type:
Conference Papers and Presentations
Status:
Published
Year Published:
2016
Citation:
Ming-Hsun Cheng, Weitao Zhang, Kurt A. Rosentrater, Jasreen J.K. Sekhon, Tong Wang, Stephanie Jung, Lawrence A. Johnson. 2016. Techno-Economic Analysis of Integrated Enzyme Assisted Aqueous Extraction of Soybean Oil. ASABE 2016 Annual Meeting, Orlando, FL, July, 2016.
- Type:
Conference Papers and Presentations
Status:
Published
Year Published:
2016
Citation:
Weitao Zhang, Kurt A Rosentrater. 2016. Environmental impact assessment (EIA) of a 40 and 120 million gallon corn-based ethanol plant model. ASABE 2016 Annual Meeting, Orlando, FL, July, 2016.
- Type:
Conference Papers and Presentations
Status:
Accepted
Year Published:
2016
Citation:
Weitao Zhang, Kurt A. Rosentrater, Jasreen J.K. Sekhon, Tong Wang, Stephanie Jung, Lawrence A. Johnson. 2016. Techno-Economic Analysis (TEA) of Biofuels Production with Integrated Corn and Soybean Biorefinery. ASABE 2016 Annual Meeting, Orlando, FL, July, 2016.
- Type:
Journal Articles
Status:
Under Review
Year Published:
2016
Citation:
Sekhon J. K., Maurer D., Rosentrater K. A., Wang T., Jung S. 2016. Effect of pretreatment of soy insoluble fiber and SSCF with Saccharomyces cerevisiae and Escherichia coli KO11 on ethanol production in an integrated corn-soy biorefinery. Bioresource Technology (under review).
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Progress 09/01/14 to 08/31/15
Outputs
Target Audience:Corn-based ethanol plants; soy processing plants; research scientists and engineers. Changes/Problems:Task 1c -- Scale-up of the optimal EAEP conditions: This portion of the study has not yet begun, due to extended delays in getting access to the pilot plant. We now have access, and will begin our pilot trials in the near future. What opportunities for training and professional development has the project provided?This project has offered the opportunity for the graduate students involved to learn new process simulation tools (such as SuperPro Designer), and they have been able to present their results at professional conferences. This information has also been shared among the research team in monthly project update meetings. How have the results been disseminated to communities of interest?Results were presented at the 2015 annual American Oil Chemists Society meeting (1 paper), and at the 2015 American Society of Agricultural and Biological Engineers conference (4 papers). One manuscript has been published in Bioresource Technology, another is currently under review, 5 conference papers were presented, and these five journal manuscripts are under development and will be submitted soon. What do you plan to do during the next reporting period to accomplish the goals?The synergistic effect of enzymes (carbohydrases and proteases) and surfactants will be optimized and results will be analyzed for ethanol production and oil recovery. The optimal conditions for each task will be combined to test synergistic effects and a scaled-up version of the fermentation will be done. After optimization, quality analysis will be conducted to determine proximate composition, free and bound amino acid composition of the soy-enhanced DDGS. This will allow us to gain a better understanding of the impact of co-fermentation on feed quality. Then, optimum conditions of objective 1 and objective 2 will be integrated and optimized. Once the integrated corn-soy fermentation has been optimized for maximum ethanol production rate, ethanol yield and oil recovery, pilot scale experiments will be performed. The by-products of the EAEP process, insoluble fiber and skim, will be used as an ingredient for bioethanol production. The EAEP process model will be combined with the bioethanol and soy production models to analyze a whole biorefinery system. Simultaneously, techno-economic analysis of commercial scales of both corn-based ethanol and soy-based factories will be completed, and economic scaling curves will be constructed. Additionally, life cycle assessments of both manufacturing systems will be undertaken. Additionally, life cycle assessments of whole systems will be conducted to determine environmental impacts.
Impacts
What was accomplished under these goals?
Objective 1) Determine how best to fully utilize the soybean cotyledon fiber fraction (EAEP soy insolubles) to enhance dry-grind corn ethanol production. Soy insoluble fiber (IF) was treated in two steps (as pretreatment for corn fermentation): simultaneous saccharification and fermentation with soy fiber hydrolyzing enzymes and yeast; and fermentation with Escherichia coli KO11. In integrated corn-soy fermentation, four corn-to-IF ratios (1:0, 1:0.04, 1:0.05, 1:0.08 and 1:0.16 by dry weight) were tested. The ratios of water-to-corn and water-to-solids in the fermentation slurry were maintained at 2.5:1 and 2.4:1 respectively. The amount of corn was kept constant in all fermentations and the amount of IF and water varied accordingly. Addition of treated IF in corn fermentation significantly increased ethanol production rate (from 1.0 ± 0.02 to 2.1 ± 0.3 g ethanol/100 g corn/h) and ethanol yield (from 36.6 ± 0.2 to 42.0 ± 1.0 g ethanol/100 g corn/h) compared to corn fermentation. Further, an increase in the amount of IF (from corn-to-treated IF ratio 1:0.04 to 1:0.2) in the soy-corn slurry resulted in a significant increase in ethanol production rate (1.7 to 2.1 g ethanol/100 g corn/h for treated IF), because IF provided additional nitrogen and promoted yeast growth. Soy IF (untreated) from EAEP was added to corn fermentation and treated with enzymes. Four corn-to-IF ratios (1:0, 1:0.04, 1:0.05, 1:0.08 and 1:0.16 by dry weight) were tested. Soy fiber hydrolyzing enzymes used were pectinase, xylanase and cellulose. Addition of these enzymes to the corn-untreated IF resulted in a significant increase in ethanol production rate (1.8 to 2.3 g ethanol/100 g corn/h) and ethanol yield (38.2 to 43.4 g ethanol/100 g corn) compared to no enzyme treatment. When corn-treated IF fermentation and corn-untreated IF fermentation with enzyme treatment were compared, ethanol production rate and ethanol yield were higher in corn-untreated IF. This suggests that pretreatment of soy insoluble fiber is not necessary and it can be treated during fermentation by addition of soy fiber hydrolyzing enzymes at the fermentation step. After EAEP, soy skim and IF were separated by centrifugation and added separately to the dry grind corn fermentation. When only soy skim was added to corn fermentation [corn + skim], a significant increase in ethanol production rate (from 1.0 ± 0.02 to 2.3 ± 0.02 g ethanol/100 g corn/h) and ethanol yield (approximately 2% increase) compared to corn only fermentation was observed. The increase in production rate reduced fermentation time from 68 h to 40 h. Skim (high in protein) contributed as an additional nitrogen source to yeast and promoted its growth rate, which in turn lead to an increase in ethanol production rate. When only soy IF was added to corn fermentation [corn + untreated IF], a significant increase in ethanol production rate (1.8 ± 0.1 g ethanol/100 g corn/h) was observed compared to [corn only] (1.0 ± 0.3 g ethanol/100 g corn/h) fermentation. Objective 2) Determine how best to fully utilize the EAEP skim (from the optimum EAEP production strategy) for oil recovery and subsequent acceleration of fuel ethanol fermentation and feed quality improvement. Experiments were conducted testing the effect of adding an enzyme with xylanase activity during fermentation or after distillation, in comparison to no enzyme addition. The ethanol production rate significantly increased with the addition of soy skim, which was in agreement with previous studies. Addition of enzymes during corn-soy fermentation significantly increased ethanol yield with the maximum yield of 42.3 g ethanol/g dry corn. Results show that co-fermentation resulted in more oil partitioning in thin stillage than in wet cake. Corn-soy co-fermentation, without enzyme or heating, had 62% oil in the thin stillage. Oil partitioning in thin stillage of co-fermentation was further increased to 70% with the use of enzyme during fermentation or after heating. Effect of addition of different proteases (Olexa and Fermgen) and carbohydrases (Bluezy P, mixture of pectinase, cellulase and xylanase) on maximizing oil recovery from corn-soy fermented slurries was evaluated. Addition of pectinase and cellulase (at 3% of soy solids) at the fermentation step significantly increased free oil recovery. Preliminary results with protease show that oil recovery (free and extractable) further increased when Fermgen was added in combination with carbohydrases (pectinase and cellulase) to the corn-soy slurry at the fermentation step. Experiments are being conducted to optimize carbohydrase and protease enzymes in the corn-soy fermentation. Tests were performed by adding a surfactant mixture (Tween 80/Span 80 in 1:1, w.w) to corn-soy slurry. At the end of corn-soy fermentation with yeast, the temperature of the slurry was increased to 80ºC and surfactant mixture was added with continuous stirring. After 10 min of mixing the slurry was decanted and free and extractable oil recovered by hexane extraction. Adding surfactant alone (added after fermentation step) or in combination with carbohydrases and/or protease (both added at the fermentation step) to the corn-soy slurry significantly increased oil recovery. Objective 3) Using experimental data, build advanced mathematical models to conduct techno-economic analyses (TEA) and life-cycle assessments (LCA) for various strategies of integrating soybean EAEP into a dry-grind corn ethanol plant, in order to identify the most profitable approach with minimum environmental impacts. SuperPro Designer (V.9.0 Intelligen, Inc.) was used to build techno-economic models for cost analyses. Models included soy oil expelling, soy oil hexane extraction, and corn-based ethanol production. These TEA models were used to test the effects of various processing and economic factors, included the cost of corn, soy, ethanol, soy oil, electricity, and other process inputs. The ethanol production model included support systems, coproduct processing, ethanol processing, starch to sugar conversion, fermentation, and grain handling and milling. While all aspects of the ethanol production process impact the economics, the purchase price of corn had the greatest impact on profitability. In terms of the soy models, hexane extraction results in a higher extraction rate than the expelling process. Due to the different processes, hexane extraction results in greater investment and operational costs. Enzymatic-assisted aqueous extraction process (EAEP) is another method of oil removal, has lower chemical hazards, and has high oil yields. An integrated and countercurrent two-stage EAEP process model was built. According to the simulation, a final oil yield of 98% from soybean can be achieved. However, this process results in higher investment and operational costs. In the simulation models, the annual amount of soybean is 219 million kg, and the annual oil yield was 45 million kg. The service time is 15 years, construction time is 30 months, and startup period is 4 months. Additionally, the ratio of solid to liquid during oil extraction was fixed at 1:6. The purchase price of soybean, selling prices of soybean oil and soybean hulls were based on industry data, and included 0.48 $/kg, 1.02 $/kg and 0.21$/kg, respectively. According to the results of simulation, the total annual revenue from soybean oil is $46,793,000, the total capital investment and operation costs are $215,452,000 and 146,592,000. Though the EAEP could result in 98% oil extraction and about 25% insoluble fiber recycle rate from soybean can be achieved, it also leads to higher operation costs and total investment. Additionally, the use of protein rich by-product, soy skim, is needed to consider for increasing the total revenue.
Publications
- Type:
Journal Articles
Status:
Published
Year Published:
2015
Citation:
Sekhon, J.K., S. Jung, T. Wang, K.A. Rosentrater, and L.A. Johnson. 2015. Effect of co-products of enzyme-assisted aqueous extraction of soybeans on ethanol production in dry-grind corn fermentation. Bioresource Technology 192:451-460.
- Type:
Conference Papers and Presentations
Status:
Published
Year Published:
2015
Citation:
Cheng, M.-H, and K. A. Rosentrater. 2015. Techno-Economic Analysis of Soybean Oil Expelling Process from 1980-2015. ASABE Annual International Conference, New Orleans, LA, July 2015.
- Type:
Conference Papers and Presentations
Status:
Published
Year Published:
2015
Citation:
Cheng, M.-H, and K. A. Rosentrater. 2015. Techno-Economic Modeling of Soybean Oil Extraction with Hexane from 1980 to 2014. ASABE Annual International Conference, New Orleans, LA, July 2015.
- Type:
Conference Papers and Presentations
Status:
Published
Year Published:
2015
Citation:
Zhang, W. and K. A. Rosentrater. 2015. Techno-Economic Analysis (TEA) of a 120 Million Gallon Corn-Based Ethanol Plant. ASABE Annual International Conference, New Orleans, LA, July 2015.
- Type:
Conference Papers and Presentations
Status:
Published
Year Published:
2015
Citation:
Sekhon J., Maurer D., Rosentrater K., Wang T., Jung S. 2015. Effect of pretreatment of soy insoluble fiber and SSCF with Saccharomyces cerevisiae and Escherichia coli KO11 on ethanol production in an integrated corn-soy biorefinery. ASABE Annual International Conference, New Orleans, LA, July 2015.
- Type:
Conference Papers and Presentations
Status:
Published
Year Published:
2015
Citation:
Sekhon, J., Jung, S., Wang, T., Rosentrater, K. A., and Johnson, L. 2015. Effects of co-products of enzyme-assisted aqueous extraction of soybeans on ethanol production in corn fermentation. AOCS Annual Meeting, San Antonio, TX, May 4-7, 2015.
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Progress 09/01/13 to 08/31/14
Outputs
Target Audience:
Nothing Reported
Changes/Problems:
Nothing Reported
What opportunities for training and professional development has the project provided? This project has offered the opportunity for the graduate students involved to learn new process simulation tools (SuperPro Designer). We project by next summer we will be able to present the results at professional meetings. This information will also be shared among fellow graduate students in presentation seminars. How have the results been disseminated to communities of interest? Results will be presented at the 2015 annual American Oil Chemists Society meeting, at the 2015 American Society of Agricultural and Biological Engineers conference, and two journal manuscripts are under preparation. What do you plan to do during the next reporting period to accomplish the goals? The enzyme treatments will be finished and the results will be analyzed for ethanol production and oil recovery. The demulsifier treatments will be carried out and analyzed for ethanol production and oil recovery. The optimal conditions for each task will be combined to test synergistic effects and a scaled-up version of the fermentation will be done. Quality analysis will be undertaken to determine proximate composition of the soy-enhanced DDGS. Free and bound amino acid composition and carbohydrate composition of whole stillage from corn-soy fermentations will be determined. This will allow us to gain a better understanding of the impact of co-fermentation. Then optimum conditions of objective 1 and objective 2 will be integrated and optimized. Once the integrated corn-soy fermentation has been optimized for maximum ethanol production rate, ethanol yield and oil recovery, pilot scale experiments will be performed. Simultaneously, techno-economic analysis of commercial scales of both corn-based ethanol and soy-based biodiesel plants will be completed, and economic scaling curves will be constructed. Additionally, life cycle assessments of both manufacturing systems will be undertaken.
Impacts
What was accomplished under these goals?
Objective 1: Task 1a –Determine if separate pre-treatment of enzyme-assisted aqueous extraction processing (EAEP) soy insoluble fiber (IF) is required before slurrying with ground corn for ethanol fermentation or if corn and soybean IF can be fermented together This task investigated two ways of integrating corn and soy IF fermentation to maximize ethanol production. Soy IF was treated in two steps (as pretreatment for corn fermentation): simultaneous saccharification and fermentation with soy fiber hydrolyzing enzymes and yeast; and fermentation with Escherichia coli KO11. Treated IF was used in dry grind corn fermentation with no modifications to the fermentation conditions. In integrated corn-soy fermentation, four corn-to-IF ratios (1:0, 1:0.04, 1:0.05, 1:0.08 and 1:0.16 by dry weight) were tested. The ratios of water-to-corn and water-to-solids in the fermentation slurry were maintained at 2.5:1 and 2.4:1 respectively. The amount of corn was kept constant in all fermentations and the amount of IF and water varied accordingly. Addition of treated IF in corn fermentation significantly increased ethanol production rate (from 1.0 ± 0.02 to 2.1 ± 0.3 g ethanol/100 g corn/h) and ethanol yield (from 36.6 ± 0.2 to 42.0 ± 1.0 g ethanol/100 g corn/h) compared to corn fermentation. Further, an increase in the amount of IF (from corn-to-treated IF ratio 1:0.04 to 1:0.2) in the soy-corn slurry resulted in a significant increase in ethanol production rate (1.7 to 2.1 g ethanol/100 g corn/h for treated IF), because IF provided additional nitrogen and promoted yeast growth. Soy IF (untreated) from EAEP was added to corn fermentation and treated with enzymes. Four corn-to-IF ratios (1:0, 1:0.04, 1:0.05, 1:0.08 and 1:0.16 by dry weight) were tested. The ratios of water-to-corn and water-to-solids in the fermentation slurry were maintained at 2.5:1 and 2.4:1 respectively. Soy fiber hydrolyzing enzymes used were pectinase, xylanase and cellulose. Addition of these enzymes to the corn-untreated IF resulted in a significant increase in ethanol production rate (1.8 to 2.3 g ethanol/100 g corn/h) and ethanol yield (38.2 to 43.4 g ethanol/100 g corn) compared to no enzyme treatment. When corn-treated IF fermentation and corn-untreated IF fermentation with enzyme treatment were compared, ethanol production rate and ethanol yield were higher in corn-untreated IF. This suggests that pretreatment of soy insoluble fiber is not necessary and it can be treated during fermentation by addition of soy fiber hydrolyzing enzymes at the fermentation step. Task 1b –Determine if EAEP soy skim and IF can be kept together and used to slurry corn for ethanol fermentation Countercurrent, two-stage EAEP of soy produces cream and oil, soy skim and soy IF. After separation of cream and oil by decanting, two approaches investigated soy skim and soy IF (untreated) in corn fermentation. After EAEP, soy skim and IF were separated by centrifugation and added separately to the dry grind corn fermentation. In the corn and skim slurry, water-to-corn ratio was set at 2.5:1 and water -to-solids ratio at 2.0:1. Skim was added to replace 75% of the water in the corn slurry. When only soy skim was added to corn fermentation [corn + skim], a significant increase in ethanol production rate (from 1.0 ± 0.02 to 2.3 ± 0.02 g ethanol/100 g corn/h) and ethanol yield (approximately 2% increase) compared to corn only fermentation was observed. The increase in production rate reduced fermentation time from 68 h to 40 h. Skim (high in protein) contributed an additional nitrogen source to yeast and promoted its growth rate, which in turn lead to an increase in ethanol production rate. When only soy IF was added to corn fermentation [corn + untreated IF], a significant increase in ethanol production rate (1.8 ± 0.1 g ethanol/100 g corn/h) was observed compared to corn only (1.0 ± 0.3 g ethanol/100 g corn/h) fermentation. In conclusion, addition of soy skim and IF, co-products of EAEP, did not negatively affect ethanol production in dry-grind corn fermentation. Soy skim and IF in the corn fermentation contributed to a significant increase in ethanol production rate and ethanol yield and a significant decrease in fermentation time. Pretreatment of soy IF before adding to corn fermentation is not necessary and untreated IF can be directly added to the corn fermentation along with corn. Further, separation of soy skim and IF after EAEP is not required and can be added in their natural ratio to the corn fermentation. Objective 2: Task 2a – Determine the effects of treating the stillage from the integrated corn/soy biorefinery with a novel combination of commercial enzymes on oil recovery and feed quality of the residual solids [i.e. soy-enhanced distiller’s dried grains with solubles (DDGS)]. Experiments were conducted testing the effect of adding an enzyme with xylanase activity during fermentation or after distillation, in comparison to no enzyme addition. Ethanol production rate and ethanol yield were. Oil recovery was quantified using hexane extraction and compared to total oil content as determined by acid hydrolysis. The ethanol production rate was significantly higher with the addition of soy skim, in agreement with previous studies. The ethanol yield was significantly different with each treatment, with the addition of enzyme during corn-soy co-fermentation having the highest yield (42.3 g ethanol per g dry corn). Results show that the co-fermentation resulted in more oil partitioning in thin stillage than in wet cake. Corn-soy co-fermentation, without enzyme or heating, had 62% oil in the thin stillage. Oil partitioning in thin stillage of co-fermentation was further increased to 70% with the use of enzyme during fermentation or after heating. Task 2b – Determine the effects of demulsifiers on oil recovery from the stillage of the integrated biorefinery and on feed quality of final product; and synergy between enzymatic and de-emulsification treatments Experiments have been designed to test the effects of adding either a commercial demulsifier, and silica nanoparticle based, or a 1:1 mixture of demulsifier with 5% silica nanoparticles. The demulsifier will be either during fermentation or after distillation, as with the enzymes. Objective 3: Task 3a –Build process models SuperPro Designer (V.9.0 Intelligen, Inc.) was used to build techno-economic models for cost analyses. Models included soy oil expelling, soy oil hexane extraction, and corn-based ethanol production. These techno-economic analyses (TEA) models can be used to test the effects of various processing and economic factors, included the cost of corn, soy, ethanol, soy oil, electricity, and other process inputs. The ethanol production model included six parts (support systems, coproduct processing, ethanol processing, fermentation, starch to sugar conversion, and grain handling and milling). While all aspects of the ethanol production process impact the economics, the purchase price of corn had the greatest impact on plant profitability. In terms of the soy models, hexane extraction results in a higher extraction rate than the expelling process, which leads to higher soy oil yield and revenues. But that does not reflect the gross margin, return on investment, or payback time. Due to the different processes, hexane extraction results in greater investment and operational costs.
Publications
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