| 1. |
- Baudel, Henrique, et al.
(författare)
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Ethanol production from steam pretreated sugarcane bagasse via simultaneous saccharification and fermentation (SSF) using cellulase and b.glucosidase enzymes
- 2008
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Ingår i: XVII Congreso Brasileiro de Engenharia Quimica. ; , s. 1-8
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Konferensbidrag (refereegranskat)abstract
- Cellulosic ethanol was produced via simultaneous enzymatic hydrolysis and fermentation of steam pretreated sugarcane bagasse. Sugarcane bagasse underwent steam pretreatments at Log Ro 3.05-4.09, under catalysed (SO2 2% and H2SO4 0.25%) and uncatalysed conditions. Digestibilities of the steam pretreated bagasse were assessed via enzymatic hydrolysis using cellulase (Celluclast 1.5L) and B-glucosidase (Novozym 188) enzyme formulations at 2% WIS, 40 ºC, pH 4.8, 72h under continuous stirring (200 rpm). SO2-catalysed steam pretreated bagasses produced at moderate severities (180 or 190 ºC, 5 minutes) presented digestibilities up to 82%. Hemicellulose removal influenced pretreatment efficiency rather than delignification. SO2-steam pretreated bagasses were processed by SSF (simultaneous saccharification and fermentation) at 5% WIS loading. Yields of 0.40-0.41 g ethanol/g glucose (approx. 80% of the theoretical) and high selectivity through ethyl alcohol were obtained for all investigated conditions, leading to a potential production of 230 L ethanol/ ton dry bagasse.
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| 2. |
- Cabaneros Lopez, Pau, et al.
(författare)
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Transforming data to information : A parallel hybrid model for real-time state estimation in lignocellulosic ethanol fermentation
- 2021
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Ingår i: Biotechnology and Bioengineering. - : Wiley. - 0006-3592 .- 1097-0290. ; 118:2, s. 579-591
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Tidskriftsartikel (refereegranskat)abstract
- Operating lignocellulosic fermentation processes to produce fuels and chemicals is challenging due to the inherent complexity and variability of the fermentation media. Real-time monitoring is necessary to compensate for these challenges, but the traditional process monitoring methods fail to deliver actionable information that can be used to implement advanced control strategies. In this study, a hybrid-modeling approach is presented to monitor cellulose-to-ethanol (EtOH) fermentations in real-time. The hybrid approach uses a continuous-discrete extended Kalman filter to reconciliate the predictions of a data-driven model and a kinetic model and to estimate the concentration of glucose (Glu), xylose (Xyl), and EtOH. The data-driven model is based on partial least squares (PLS) regression and predicts in real-time the concentration of Glu, Xyl, and EtOH from spectra collected with attenuated total reflectance mid-infrared spectroscopy. The estimations made by the hybrid approach, the data-driven models and the internal model were compared in two validation experiments showing that the hybrid model significantly outperformed the PLS and improved the predictions of the internal model. Furthermore, the hybrid model delivered consistent estimates even when disturbances in the measurements occurred, demonstrating the robustness of the method. The consistency of the proposed hybrid model opens the doors towards the implementation of advanced feedback control schemes.
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| 3. |
- Carrasco, Cristhian, et al.
(författare)
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Fermentation of the Straw Material Paja Brava by the Yeast Pichia stipitis in a Simultaneous Saccharification and Fermentation Process
- 2013
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Ingår i: Journal of Sustainable Bioenergy Systems. - : Scientific Research Publishing, Inc.. - 2165-4018 .- 2165-400X. ; 3:2, s. 99-106
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Tidskriftsartikel (refereegranskat)abstract
- Paja Brava is a native South American grass with a high carbohydrate content. In the current work, the potential of us- ing this feedstock for ethanol production using a simultaneous saccharification and fermentation (SSF) process with the xylose-fermenting yeast Pichia stipitis (Scheffersomyces stipitis) CBS6054 was investigated. The straw material was subjected to SO2 catalyzed steam pretreatment at 200°C and 5 min residence time, which resulted in a solubilization of pentose sugars (mainly xylose) of 64% with only minor amounts of degradation products. The obtained material, in- cluding the pretreatment liquid, was subsequently hydrolyzed and fermented in an SSF process at microaerobic condi- tions using either a batch or a fed-batch process at a total water-insoluble solids loading of 10%. Overall yields of etha- nol based on all available sugars of 0.24 g/g and 0.27 g/g were obtained for batch and fed-batch mode of operation, re- spectively. The higher yield in the fed-batch process coincided with a higher degree of conversion of the sugars in the liquid medium, in particular of arabinose, for which the conversion was doubled (from 48% to 97%).
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| 4. |
- Carrasco, Cristhian, et al.
(författare)
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SO2-catalyzed steam pretreatment and fermentation of enzymatically hydrolyzed sugarcane bagasse
- 2010
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Ingår i: Enzyme and Microbial Technology. - : Elsevier BV. - 0141-0229. ; 46:2, s. 64-73
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Tidskriftsartikel (refereegranskat)abstract
- Sugarcane bagasse is a lignocellulosic residue obtained from sugarcane milling, and a potentially interesting raw material that can be used for fuel ethanol production. In the present study, bagasse was steam pretreated at temperatures between 180 and 205 ◦C, with holding times of 5–10 min using SO2 as a catalyst to determine conditions that provide a good recovery of pentoses and a suitable material for enzymatic hydrolysis. Pretreatment conducted at 190 ◦C for 5 min gave a pentose yield of 57%, with only minor amounts of degradation compounds formed. Commercial cellulolytic enzymes were used to hydrolyze the obtained fiber fractions after pretreatment at different water-insoluble solid contents (2%, 5% and 8% WIS). The overall highest sugar yield achieved from bagasse was 87% at 2% WIS. Fermentation tests were made on both the pentose-rich hemicellulose hydrolysate obtained from the pretreatment, and the enzymatic hydrolysates obtained from the fiber fractions using the xylose-fermenting strain of Saccharomyces cerevisiae TMB3400, as well as the natural xylose-utilizing yeast Pichia stipitis CBS 6054. The pretreatment hydrolysates produced at 2% WIS as well as the enzymatic hydrolysates showed a complete glucose fermentability indicating a low toxicity to the yeasts. The best xylose conversion (more than 60%) was achieved by the strain TMB3400 at 2% WIS.
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| 5. |
- Carrasco, Cristhian, et al.
(författare)
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Steam pretreatment and fermentation of the straw material "Paja Brava" using simultaneous saccharification and co-fermentation.
- 2011
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Ingår i: Journal of Bioscience and Bioengineering. - : Elsevier BV. - 1347-4421 .- 1389-1723. ; 111, s. 167-174
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Tidskriftsartikel (refereegranskat)abstract
- Pretreatment, enzymatic hydrolysis and simultaneous saccharification and fermentation (SSF) of the South American straw material Paja Brava were investigated. Suitable process conditions for an SO(2)-catalyzed steam pretreatment of the material were determined and assessed by enzymatic digestibility of obtained fiber slurries for 72h at a water insoluble solids (WIS) content of 2%. The best pretreatment conditions obtained (200°C, 5min holding time and 2.5% SO(2)) gave an overall glucose yield following enzymatic hydrolysis of more than 90%, and a xylose yield of about 70%. Simultaneous saccharification and co-fermentation of glucose and xylose (SSCF) of the pretreated material using the xylose-fermenting strain Saccharomyces cerevisiae TMB3400 was examined at WIS contents between 5% and 10%. In agreement with previous studies on other materials, the overall ethanol yield and also the xylose conversion decreased somewhat with increasing WIS content in the SSCF. In batch SSCF, the xylose conversion obtained was almost 100% at 5% WIS content, but decreased to 69% at 10% WIS. The highest ethanol concentration obtained for a WIS content of 10% was about 40g/L, corresponding to a yield of 0.41g/g in a fed-batch SSCF. The Paja Brava material has previously been found difficult to hydrolyze in a dilute-acid process. However, the SSCF results obtained here show that similar sugar yields and fermentation performance can be expected from Paja Brava as from materials such as wheat straw, corn stover or sugarcane bagasse.
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| 6. |
- Garcia-Aparicio, Maria, et al.
(författare)
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Evaluation of Steam-Treated Giant Bamboo for Production of Fermentable Sugars
- 2011
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Ingår i: Biotechnology Progress. - : Wiley. - 1520-6033 .- 8756-7938. ; 27:3, s. 641-649
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Tidskriftsartikel (refereegranskat)abstract
- Giant bamboo plantations are currently being established in the Southern Africa region and can be considered as potential lignocellulosic feedstock for the production of second generation bioethanol. In this study, giant bamboo internodal material was subjected to sulphur dioxide (SO2) impregnated steam pretreatment prior to enzymatic hydrolysis. The effect of temperature, residence time, and acidity on the overall sugar recovery and byproduct formation was studied using response surface response technology according to a central composite experimental design (CCD) at a fixed SO2 concentration of 2.5% (w/w liquid) after impregnation. The results showed that pretreatment conditions with combined severity factor (CSF) values and enzyme dosages greater than 1.72 and 30 FPU/g water insoluble solid, respectively, were required to obtain an efficient glucan digestibility and a good overall glucose recovery. Up to 81.2% of the sugar in the raw material was recovered for a CSF of 2.25. However, considering overall sugar yield and byproducts concentration, the pretreated material obtained with a CSF of 1.62 can be considered as the most appropriate for SSF experiments using a xylose-utilizing yeast. At these conditions, it could be possible to obtain up to 247 L of ethanol per dry ton of giant bamboo considering hexose and pentose sugars fermentation. This amount could be increased up to 292 L of ethanol per dry ton of giant bamboo with the maximum sugar yield obtained (CSF 2.25) if the microorganism possesses robust fermentative characteristics as well as a high resistance to pretreatment by-products. (C) 2011 American Institute of Chemical Engineers Biotechnol. Prog., 27: 641-649, 2011
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| 7. |
- Geddes, C. C., et al.
(författare)
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Optimizing the saccharification of sugar cane bagasse using dilute phosphoric acid followed by fungal cellulases
- 2010
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Ingår i: Bioresource Technology. - : Elsevier BV. - 1873-2976 .- 0960-8524. ; 101:6, s. 1851-1857
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Tidskriftsartikel (refereegranskat)abstract
- A low level of phosphoric acid (1% w/w on dry bagasse basis, 160 degrees C and above, 10 min) was shown to effectively hydrolyze the hemicellulose in sugar cane bagasse into monomers with minimal side reactions and to serve as an effective pre-treatment for the enzymatic hydrolysis of cellulose. Up to 45% of the remaining water-insoluble solids (WIS) was digested to sugar monomers by a low concentration of Biocellulase W (0.5 filter paper unit/g WIS) supplemented with beta-glucosidase, although much higher levels of cellulase (100-fold) were required for complete hydrolysis. After neutralization and nutrient addition, phosphoric acid syrups of hemicellulose sugars were fermented by ethanologenic Escherichia coli LY160 without further purification. Fermentation of these syrups was preceded by a lag that increased with increased pre-treatment temperature. Further improvements in organisms and optimization of steam treatments may allow the co-fermentation of sugars derived from hemicellulose and cellulose, eliminating need for liquid-solid separation, sugar purification, and separate fermentations. (C) 2009 Elsevier Ltd. All rights reserved.
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| 8. |
- Lopez, Pau Cabaneros, et al.
(författare)
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Towards a digital twin : a hybrid data-driven and mechanistic digital shadow to forecast the evolution of lignocellulosic fermentation
- 2020
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Ingår i: Biofuels, Bioproducts and Biorefining. - : Wiley. - 1932-104X .- 1932-1031. ; 14:5, s. 1046-1060
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Tidskriftsartikel (refereegranskat)abstract
- The high substrate variability and complexity of fermentation media derived from lignocellulosic feedstock affects the concentration profiles and the length of the fermentation. Failing to account for such variability raises operational and scheduling issues and affects the overall performance of these processes. In this work, a hybrid soft sensor was developed to monitor and forecast the evolution of cellulose-to-ethanol fermentation. The soft sensor consisted of two modules (a data-driven model and a kinetic model) connected sequentially. The data-driven module used a partial-least-squares model to estimate the current state of glucose from spectroscopic data. The kinetic model was recursively fitted to known concentrations of glucose to update the long-horizon predictions of glucose, xylose, and ethanol. This combination of real-time data update from an actual fermentation process to a high-fidelity kinetic model constitutes the basis of the digital twin concept and allows for a better real-time understanding of complex inhibition phenomena caused by different inhibitors commonly found in lignocellulosic feedstocks. The soft sensor was experimentally validated with three different cellulose-to-ethanol fermentations and the results suggested that this method is suitable for monitoring and forecasting fermentation when the measurements provide reasonably good estimates of the real state of the system. These results would allow the flexibility of the operation of cellulosic processes to be increased, and would permit the scheduling to be adapted to the inherent variability of such substrates.
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| 9. |
- Montipó, Sheila, et al.
(författare)
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Steam Pretreatment of Rice Hulls to Release Fermentable Saccharides : An Approach to Improve Recovery of (Hemi)Cellulosic Sugars Through Multivariate Design
- 2021
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Ingår i: Rice Science. - : Elsevier BV. - 1672-6308. ; 28:5, s. 501-510
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Tidskriftsartikel (refereegranskat)abstract
- The conversion of rice hulls into fermentable saccharides was explored through steam pretreatment employing 2.5% SO2. The interaction between temperature and time was assessed by means of the response surface method to achieve optimum contents of C6-sugars in water-insoluble solids (WIS) and C5-sugars in the liquor. Pretreatment carried out at 218 °C for 2.3 min released liquor containing 55.4 g/L of sugars (29.1 g/L of xylose). In parallel, the WIS was subjected to enzymatic saccharification using different solid and enzyme loads via an experimental design: assays using 22.0% WIS and 20.0 filter paper units (FPU)/g led to 90.6 g/L of glucose, corresponding to a yield of 86.4% and an overall yield of 72.4%. The data reported are the highest ever found for such raw material, making it attractive to compete with conventional lignocellulosic biomass.
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| 10. |
- Sanchez, Gladys, et al.
(författare)
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Dilute-acid hydrolysis for fermentation of the Bolivian straw material Paja Brava
- 2004
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Ingår i: Bioresource Technology. - : Elsevier BV. - 1873-2976 .- 0960-8524. ; 93:3, s. 249-256
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Tidskriftsartikel (refereegranskat)abstract
- Hydrolysis of the straw material Paja Brava, a sturdy grass characteristic for the high plains of Bolivia, was studied in order to find suitable conditions for hydrolysis of the hemicellulose and cellulose parts. Dried Paja Brava material was pre-steamed, impregnated with dilute sulfuric acid (0.5% or 1.0% by wt), and subsequently hydrolyzed in a reactor at temperatures between 170 and 230 degreesC for a reaction time between 3 and 10 min. The highest yield of xylose (indicating efficient hydrolysis of hemicellulose) were found at a temperature of 190 degreesC, and a reaction time of 5-10 min, whereas considerably higher temperatures (230 degreesC) were needed for hydrolysis of cellulose. Fermentability of hemicellulose hydrolyzates was tested using the xylose-fermenting yeast species Pichia stipitis, Candida shehatae and Pachysolen tannophilus. The fermentability of hydrolyzates decreased strongly for hydrolyzates produced at temperatures higher than 200 degreesC. (C) 2003 Elsevier Ltd. All rights reserved.
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