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  • 1. Abedinifar, Sorahi
    et al.
    Karimi, Keikhosro
    University of Borås, School of Engineering.
    Khanahmadi, Morteza
    Taherzadeh, Mohammad J.
    University of Borås, School of Engineering.
    Ethanol production by Mucor indicus and Rhizapus oryzae from rice straw by separate hydrolysis and fermentation2009In: Biomass and Bioenergy, ISSN 0961-9534, E-ISSN 1873-2909, Vol. 33, no 5, 828-833 p.Article in journal (Refereed)
    Abstract [en]

    Rice straw was successfully converted to ethanol by separate enzymatic hydrolysis and fermentation by Mucor indicus, Rhizopus oryzae, and Saccharomyces cerevisiae. The hydrolysis temperature and pH of commercial cellulase and beta-glucosidase enzymes were first investigated and their best performance obtained at 45 degrees C and pH 5.0. The pretreatment of the straw with dilute-acid hydrolysis resulted in 0.72 g g (1) sugar yield during 48 h enzymatic hydrolysis, which was higher than steam-pretreated (0.60 g g (1)) and untreated straw (0.46 g g(-1)). Furthermore, increasing the concentration of the dilute-acid pretreated straw from 20 to 50 and 100 g L-1 resulted in 13% and 16% lower sugar yield, respectively. Anaerobic cultivation of the hydrolyzates with M. indicus resulted in 0.36-0.43 g g(-1) ethanol, 0.11-0.17 g g(-1) biomass, and 0.04-0.06 g g(-1) glycerol, which is comparable with the corresponding yields by S. cerevisiae (0.37-0.45 g g(-1) ethanol, 0.04-0.10 g g(-1) biomass and 0.05-0.07 glycerol). These two fungi produced no other major metabolite from the straw and completed the cultivation in less than 25 h. However, R. oryzae produced lactic acid as the major by-product with yield of 0.05-0.09 g g(-1). This fungus had ethanol, biomass and glycerol yields of 0.33-0.41, 0.06-0.12, and 0.03-0.04 g g(-1), respectively. Crown Copyright (C) 2009 Published by Elsevier Ltd. All rights reserved.

  • 2. Akbari, H.
    et al.
    Karimi, K
    University of Borås, School of Engineering.
    Lundin, M
    University of Borås, School of Engineering.
    Taherzadeh, Mohammad J.
    University of Borås, School of Engineering.
    Optimization of baker's yeast drying in industrial continuous fluidized-bed dryer2012In: Food and Bioproducts Processing, ISSN 0960-3085, E-ISSN 1744-3571, Vol. 90, no 1, 52-57 p.Article in journal (Refereed)
    Abstract [en]

    Instant active dry baker's yeast is a well-known product widely used for leavening of bread, produced by fermentation, and usually dried by hot air to 94–96% dry matter content. Multi-stage fluidized bed drying process is a commercial effective method for yeast drying. In this work, optimum operating parameters of an industrial continuous fluidized bed dryer for the production of instant active dry yeast were investigated. The dryer contained four zones separated with moving weirs. The operating conditions such as temperature, loading rate of compressed yeast granules, and hot air humidity had direct effects on both yeast activity and viability. The most important factors that affected the quality of the product were loading rate and the operational temperature in each zone on the bed. Optimization was performed for three loading rates of the feed to the dryer, using response surface methodology for the experimental design. The most significant factor was shown to be the loading rate with mean fermentation activity values of 620, 652, and 646 cm3 CO2/h for 300, 350, and 400 kg/h loading rates, respectively. The data analysis resulted in an optimal operating point at a loading rate of 350 kg/h and temperatures of zones 1, 2, 3, and 4 controlled at 33, 31, 31, and 29 °C, respectively. The best activity value was predicted as 668 ± 18 cm3 CO2/h, and confirmation experiments resulted in 660 ± 10 cm3 CO2/h. At the same operating point, the average viability of the cells was predicted as 74.8 ± 3.7% and confirmed as 76.4 ± 0.6%. Compared with the normal operating conditions at the plant, the optimization resulted in more than 12% and 27% improvement in the yeast activity and viability, respectively.

  • 3. Akbari, H.
    et al.
    Karimi, K.
    University of Borås, School of Engineering.
    Taherzadeh, M.J.
    University of Borås, School of Engineering.
    Optimization of baker´s yeast drying in industrial continuous fluidized-bed dryer2008Conference paper (Refereed)
  • 4. Asachi, R.
    et al.
    Karimi, K.
    University of Borås, School of Engineering.
    Taherzadeh, M.J.
    University of Borås, School of Engineering.
    Fungal autolysate as a nutrient supplement for ethanol and chitosan production by Mucor indicus2011In: Biotechnology letters, ISSN 0141-5492, E-ISSN 1573-6776, Vol. 33, no 12, 2405-2409 p.Article in journal (Refereed)
    Abstract [en]

    Mucor indicus can be used to produce ethanol from a variety of sugars, including pentose's. An extract of it, produced by autolysis, could replace yeast extract in culture medium with improved production of ethanol. At 10 g l(-1), the extract gave a higher ethanol yield (0.47 g g(-1)) and productivity (0.71 g l(-1) h(-1)) compared to medium containing yeast extract (yield 0.45 g g(-1); productivity 0.67 g l(-1) h(-1)).

  • 5. Asachi, Reihaneh
    et al.
    Karimi, Keikhosro
    University of Borås, School of Engineering.
    Taherzadeh, Mohammad J.
    University of Borås, School of Engineering.
    Ethanol production by Mucor indicus using the fungal autolysate as a nutrient supplement2011In: WREC11 World Renewable Energy Conference 2011, Linköping University Electronic Press , 2011, 1-6 p.Conference paper (Refereed)
  • 6. Beigi, H.M.
    et al.
    Karimi, Keikhosro
    University of Borås, School of Engineering.
    Effects of temperature, pH and glucose concentration on bioethanol production by Mucor indicus2009Conference paper (Other academic)
  • 7. Brandberg, T.
    et al.
    Karimi, K.
    University of Borås, School of Engineering.
    Taherzadeh, M.J.
    University of Borås, School of Engineering.
    Franzén, C.J.
    Gustafsson, L.
    Continuous fermentation of wheat-supplemented lignocellulose hydrolysate with different types of cell retention2007In: Biotechnology and Bioengineering, ISSN 0006-3592, E-ISSN 1097-0290, Vol. 98, no 1, 80- p.Article in journal (Refereed)
    Abstract [en]

    Medium supplementation and process alternatives for fuel ethanol production from dilute acid lignocellulose hydrolysate were investigated. Dilute acid lignocellulose hydrolysate supplemented with enzymatically hydrolysed wheat flour could sustain continuous anaerobic cultivation of Saccharomyces cerevisiae ATCC 96581 if further supplemented with ammonium sulphate and biotin. This medium composition allowed for a hexose utilisation of 73% and an ethanol production of 36 mmol l-1 h-1 in chemostat cultivation at dilution rate 0.10 h-1. Three different methods for cell retention were compared for improved fermentation of supplemented lignocellulose hydrolysate: cell recirculation by filtration, cell recirculation by sedimentation and cell immobilisation in calcium alginate. All three cell retention methods improved the hexose conversion and increased the volumetric ethanol production rate. Recirculation of 75% of the bioreactor outlet flow by filtration improved the hexose utilisation from 76% to 94%. Sedimentation turned out to be an efficient method for cell separation; the cell concentration in the reactor was 32 times higher than in the outflow after 60 h of substrate feeding. However, chemostat and continuous cell recirculation cultures became severely inhibited when the dilution rate was increased to 0.20 h-1. In contrast, an immobilised system kept producing ethanol at a stable level also at dilution rate 0.30 h-1. Biotechnol. Bioeng. 2007; 98: 80-90. © 2007 Wiley Periodicals, Inc.

  • 8. Cabrera-Rodríquez, Emir
    et al.
    Curbelo-Hernández, Caridad
    Karimi, Keikhosro
    University of Borås, School of Engineering.
    Taherzadeh, Mohammad J.
    University of Borås, School of Engineering.
    Effect of sodium hydroxide pretreatment at low temperature on chemical composition and enzymatic hydrolysis of spruce2013In: Revista CENIC Ciencias Químicas, ISSN 2221-2442, Vol. 43, no 1, 1-9 p.Article in journal (Refereed)
    Abstract [en]

    The availability of fermentable sugars is a limiting factor for large-scale production of biological products such as bioethanol. Therefore, processes to produce sugars are being developed from lignocellulosic materials by enzymatic hydrolysis. However, the cellulose fraction are not readily accessible for the hydrolyzing enzymes and an efficient hydrolysis requires pretreatment. Several processes have been investigated for this pretreatment. Pretreatment of lignocelluloses with NaOH is among the promissing methods. In the present work, the effect of NaOH pretreatment at low temperature on chemical composition and subsequent enzymatic hydrolysis of spruce was investigated. A native spruce specie obtained from the forest around Borås city in Sweden was used in an the experiments. This wood was analyzed for carbohydrate and lignin fractions according to NREL methods. The wood was chemically pretreated using 7 % (w/w) sodium hydroxide solution with 5 % (w/v) solid content at 0 °C for 0.5, 1, 2 and 3 h. Commercial enzymes, cellulase (Celluclast 1.5 L, Novozyme, Denmark) and β-glucosidase (Novozyme 188, Novozyme, Denmark) were used in the enzymatic hydrolysis with activities of 30 FPU and 50 IU per gram of wood, respectively. The pretreatments changed the material composition. It was a very low loss of carbohydrate, about 98 % recovery, suggesting no significant carbohydrate hydrolysis. Xylans were the most affected by the pretreatments. The largest xylan removal was almost 50 %, using sodium hydroxide solution for 3 h. The profile of released sugars were also analyzed and compared. An improvement of enzymatic hydrolysis yield was observed as a result of the applied pretreatments, near 40 % glucose yield could be achieved.

  • 9. Carrillo Nieves, Danay
    et al.
    Karimi, Keikhosro
    University of Borås, School of Engineering.
    Sárvári Horvátha, Ilona
    University of Borås, School of Engineering.
    Improvement of biogas production from oil palm empty fruit bunches (OPEFB)2011In: Industrial crops and products (Print), ISSN 0926-6690, E-ISSN 1872-633X, Vol. 34, no 1, 1097-1101 p.Article in journal (Refereed)
    Abstract [en]

    Oil palm empty fruit bunches (OPEFB), a waste lignocellulosic material, which is the main byproduct of vegetable oil production industries in Indonesia and Malaysia, was utilized as a source for biogas production. Pretreatments using NaOH as well as phosphoric acid were investigated to improve the biogas production. Clear positive effects of the pretreatments on the yield of methane were observed. The best improvement was achieved when 8% NaOH for 60 min was used for the pretreatment, which resulted in 100% improvement in the yield of methane production. In addition, treatment with phosphoric acid resulted in 40% improvement in the methane yield compared with that of the untreated material. The results showed that the carbohydrate content of OPEFB could be efficiently converted to methane under the anaerobic digestion process. 97% of the theoretical value of methane production was achieved after the pretreatment with NaOH for 60 min. Moreover, the initial rate of methane production was also increased by more than 85% after the treatment with NaOH compared with that of the untreated OPEFB.

  • 10. Christia, Abdi
    et al.
    Setiowati, Arima Diah
    Millati, Ria
    Karimi, Keikhosro
    University of Borås, Faculty of Textiles, Engineering and Business.
    Cahyanto, Muhammad Nur
    Niklasson, Claes
    Taherzadeh, Mohammad J.
    University of Borås, Faculty of Textiles, Engineering and Business.
    Ethanol production from alkali-pretreated oil palm empty fruit bunch by simultaneous saccharification and fermentation with mucor indicus2016In: International Journal of Green Energy, ISSN 1543-5075, E-ISSN 1543-5083, Vol. 13, no 6, 566-572 p.Article in journal (Refereed)
    Abstract [en]

    Oil palm empty fruit bunch (OPEFB) is a potential raw material for production of lignocellulosic bioethanol. The OPEFB was pretreated with 8% sodium hydroxide solution at 100 °C for 10 to 90 min. Enzymatic digestion was carried out using cellulase and β-glucosidase at 45 °C for 24 h. It was then inoculated with Mucor indicus spores suspension and fermented under anaerobic conditions at 37 °C for 96 h. Sodium hydroxide pretreatment effectively removed 51-57% of lignin in the OPEFB and also its hemicellulose (40-84%). The highest glucan digestibility (0.75 g/g theoretical glucose) was achieved in 40 min NaOH pretreatment. Fermentation by M. indicus resulted in 68.4% of the theoretical ethanol yield, while glycerol (16.2-83.2 mg/g), succinic acid (0-0.4 mg/g), and acetic acid (0-0.9 mg/g) were its by-products. According to these results, the 11.75 million tons of dry OPEFB in Indonesia can be converted to 1.5 billion litres of ethanol per year.

  • 11.
    Garcia, Ariel
    et al.
    University of Borås, Faculty of Textiles, Engineering and Business.
    Lopez, Yoney
    University of Borås, Faculty of Textiles, Engineering and Business.
    Karimi, Keikhosro
    University of Borås, Faculty of Textiles, Engineering and Business.
    Benitez, Augustin
    University of Borås, Faculty of Textiles, Engineering and Business.
    Lundin, Magnis
    University of Borås, Faculty of Textiles, Engineering and Business.
    Taherzadeh, Mohammad J
    University of Borås, Faculty of Textiles, Engineering and Business.
    Martin, Carlos
    University of Borås, Faculty of Textiles, Engineering and Business.
    Chemical and physical characterization and acid hydrolysis of a mixture of Jatropha curcas shells and husks2015In: Cellulose Chemistry and Technology, ISSN 0576-9787, Vol. 49, no 9-10, 737-744 p.Article in journal (Refereed)
    Abstract [en]

    Jatropha curcas L. is a tropical plant with considerable potential for producing biodiesel and other products of high economic and social interest. During the biodiesel production process from J. curcas different residues, such as shells and husks are generated. In this work, the physical characterization of J. curcas fruits was performed, and the chemical composition of a mixture of shells and husks was determined. The physical characterization revealed that shells and husks account, respectively, for 25.0 and 27.8% of the fruit weight. The compositional analyses of the material showed a rather high content of glucans (32.8% w/w) and xylans (16.4% w/w), which indicates the potential of J. curcas shells and husks for production of ethanol, xylitol and other glucose- and xylose-derived products. Acid hydrolysis was applied to a mixture of shells and husks under different sulphuric acid concentrations (from 0.5 to 4.5%), temperatures (170 – 220ºC) and time (10 – 20 min), and the hydrolytic conversion of xylan was evaluated. A zone of experimental conditions giving maximal xylan conversion was identified at around 4% H2SO4, 180ºC and reaction time below 10 min.

  • 12. Goshadrou, Amir
    et al.
    Karimi, Keikhosro
    University of Borås, School of Engineering.
    Taherzadeh, Mohammad J.
    University of Borås, School of Engineering.
    Bioethanol production from sweet sorghum bagasse by Mucor hiemalis2011In: Industrial crops and products (Print), ISSN 0926-6690, E-ISSN 1872-633X, Vol. 34, no 1, 1219-1225 p.Article in journal (Refereed)
    Abstract [en]

    The present work deals with production of ethanol from sweet sorghum bagasse by a zygomycetes fungus Mucor hiemalis. The bagasse was treated with phosphoric acid and sodium hydroxide, with or without ultrasonication, prior to enzymatic hydrolysis by commercial cellulase and β-glucosidase enzymes. The phosphoric acid pretreatment was performed at 50 °C for 30 min, while the alkali treatment performed with 12% NaOH at 0 °C for 3 h. The pretreatments resulted in improving the subsequent enzymatic hydrolysis to 79–92% of the theoretical yield. The best hydrolysis performance was obtained after pretreatment by NaOH assisted with ultrasonication. The fungus showed promising results in fermentation of the hydrolyzates. In the best case, the hydrolyzate of NaOH-ultrasound pretreated bagasse followed by 24 h fermentation resulted in about 81% of the corresponding theoretical ethanol yield. Furthermore, the highest volumetric ethanol productivity was observed in the hydrolyzates of NaOH pretreated bagasse, especially after ultrasonication in pretreatment stage.

  • 13. Goshadrou, Amir
    et al.
    Karimi, Keikhosro
    University of Borås, School of Engineering.
    Taherzadeh, Mohammad J.
    University of Borås, School of Engineering.
    Ethanol and biogas production from birch by NMMO pretreatment2013In: Biomass and Bioenergy, ISSN 0961-9534, E-ISSN 1873-2909, Vol. 49, 95-101 p.Article in journal (Refereed)
    Abstract [en]

    Birch wood was pretreated with N-methylmorpholine-N-oxide (NMMO or NMO) followed by enzymatic hydrolysis and fermentation to ethanol or digestion to biogas. The pretreatments were carried out with NMMO (wNMMO ¼ 85%) at 130 C for 3 h, and the effects of drying after the pretreatment were investigated. Enzymatic hydrolysis of the untreated wood resulted in 8%e10% of theoretical glucose yield after 4 days hydrolysis, while the NMMO pretreatment improved this yield to 91%. Consequently, ethanol production yield from NMMO-pretreated materials resulted in around 9-fold improvement compared to the untreated wood. On the other hand, drying of the pretreated wood had a negative impact and decreased the yield of enzymatic hydrolysis by 4%e10%. Digestion of the untreated wood with thermophilic bacteria resulted in maximum methane yield of 158 cm3 g 1 of VS in 30 days, while the NMMO pretreatment improved the methane yield up to 232 cm3 g 1 of VS (80% of the theoretical biogas yield) in just 9 days.

  • 14. Goshadrou, Amir
    et al.
    Karimi, Keikhosro
    University of Borås, School of Engineering.
    Taherzadeh, Mohammad J.
    University of Borås, School of Engineering.
    Improvement of sweet sorghum bagasse hydrolysis by alkali and acidic pretreatments2011In: WREC11 World Renewable Energy Conference 2011, Linköping University Electronic Press , 2011, 1-7 p.Conference paper (Refereed)
  • 15. Jafari, Vahid
    et al.
    Jeihanipour, Azam
    University of Borås, School of Engineering.
    Karimi, Keikhosro
    University of Borås, School of Engineering.
    Taherzadeh, Mohammad
    University of Borås, School of Engineering.
    Conversion of Waste Wallpaper to Ethanol2009Conference paper (Other academic)
  • 16. Jafari, Vahid
    et al.
    Labafzadeh, Sara R.
    Jeihanipour, Azam
    University of Borås, School of Engineering.
    Karimi, Keikhosro
    University of Borås, School of Engineering.
    Taherzadeh, Mohammad J.
    University of Borås, School of Engineering.
    Construction and demolition lignocellulosic wastes to bioethanol2011In: Renewable energy, ISSN 0960-1481, E-ISSN 1879-0682, Vol. 36, no 11, 2771-2775 p.Article in journal (Refereed)
    Abstract [en]

    This work deals with conversion of four construction and demolition (C&D) lignocellulosic wastes including OSB, chipboard, plywood, and wallpaper to ethanol by separate enzymatic hydrolysis and fermentation (SHF). Similar to other lignocelluloses, the wastes were resistant to the enzymatic hydrolysis, in which only up to 7% of their cellulose was hydrolyzed. Therefore, the lignocellulosic wastes were treated with phosphoric acid, sodium hydroxide, or N-methylmorpholine-N-oxide (NMMO), which resulted in improving the subsequent enzymatic hydrolysis to 38.2–94.6% of the theoretical yield. The best performance was obtained after pretreatment by concentrated phosphoric acid, followed by NMMO. The pretreated and hydrolyzed C&D wastes were then successfully fermented by baker’s yeast to ethanol with 70.5–84.2% of the theoretical yields. The results indicate the possibility of producing 160 ml ethanol from each kg of the C&D wastes at the best conditions.

  • 17.
    Jeihanipour, A.
    et al.
    University of Borås, School of Engineering.
    Karimi, K.
    University of Borås, School of Engineering.
    Taherzadeh, M.J.
    University of Borås, School of Engineering.
    Antimicrobial properties of fungal chitosan2007In: Research Journal of Biological Sciences, ISSN 1815-8846, E-ISSN 1993-6087, Vol. 2, no 3, 239- p.Article in journal (Refereed)
    Abstract [en]

    Cell wall of zygomycetes fungus is an alternative source for chitosan production. In this study chitosan was extracted from cell wall of filamentous fungus Rhizopus oryzae and its antimicrobial properties was studied against three typical human pathogenic microorganisms, Escherichia coli, Klebsiella pneumoniae and Staphylococcus aureus. The viability of these bacteria reduced by more than 60%, when 200 ppm of the fungal chitosan was present in the solution. However, the Minimum Bactericidal Concentration (MBC) of the fungal chitosan was 300, 500 and 700 ppm for S. aureus, E. coli and K. pneumoniae, respectively. The antimicrobial activity of fungal chitosan was lower than that of crustacean shells chitosan, which had MBC of less than 100 ppm for the above mentioned bacteria. Furthermore, fungal chitosan similar to crustacean shells chitosan exhibited better inhibitory effects against gram-positive compared to gram-negative bacteria. The possible mechanism for antimicrobial activity of fungal chitosan could be the disruption of the outer membrane of cells but not preventing the nutrients from entering into the cell.

  • 18. Jeihanipour, A.
    et al.
    Karimi, K.
    University of Borås, School of Engineering.
    Taherzadeh, Mohammad
    University of Borås, School of Engineering.
    Enhancement of ethanol and biogas production from high-crystalline cellulose by different modes of NMO pretreatment2010In: Biotechnology and Bioengineering, ISSN 0006-3592, E-ISSN 1097-0290, Vol. 105, no 3, 469-476 p.Article in journal (Refereed)
    Abstract [en]

    Pretreatment of high-crystalline cellulose with N-methyl-morpholine-N-oxide (NMO or NMMO) to improve bioethanol and biogas production was investigated. The pretreatments were performed at 90 and 120°C for 0.5–15 h in three different modes, including dissolution (85% NMO), ballooning (79% NMO), and swelling (73% NMO). The pretreated materials were then enzymatically hydrolyzed and fermented to ethanol or anaerobically digested to biogas (methane). The pretreatment at 85% NMO, 120°C and 2.5 h resulted in 100% yield in the subsequent enzymatic hydrolysis and around 150% improvement in the yield of ethanol compared to the untreated and water-treated material. However, the best results of biogas production were obtained when the cellulose was treated with swelling and ballooning mode, which gave almost complete digestion in 15 days. Thus, the pretreatment resulted in 460 g ethanol or 415 L methane from each kg of cellulose. Analysis of the structure of treated and untreated celluloses showed that the dissolution mode can efficiently convert the crystalline cellulose I to cellulose II. However, it decreases the water swelling capacity of the cellulose. On the other hand, swelling and ballooning modes in NMO treatment were less efficient in both water swelling capacity and cellulose crystallinity. No cellulose loss, ambient pressure, relatively moderate conditions, and high efficiency make the NMO a good alternative for pretreatment of high-crystalline cellulosic materials.

  • 19.
    Jeihanipour, Azam
    et al.
    University of Borås, School of Engineering.
    Karimi, Keikhosro
    University of Borås, School of Engineering.
    Taherzadeh, Mohammad
    University of Borås, School of Engineering.
    Effective pretreatment of high crystalline cellulose by NMMO2009Conference paper (Other academic)
  • 20.
    Jeihanipour, Azam
    et al.
    University of Borås, School of Engineering.
    Karimi, Keikhosro
    University of Borås, School of Engineering.
    Taherzadeh, Mohammad J.
    University of Borås, School of Engineering.
    Acid Hydrolysis of Cellulose-based Waste Textiles2011Conference paper (Refereed)
    Abstract [en]

    The present study focused on conversion of cellulosic part of waste textiles into biogas and its challenges. The annual global fiber consumption exceeded 70 Mt with a cellulosic fraction of around 40%. This huge amount of fiber is further processed into apparel, home textiles and industrial products and after a certain time delay end up in waste streams. This amount of cellulose has the potential of production of approximately 20 billion liters of ethanol. Assuming a good collection and waste management system, however, there are still challenges facing the process of conversion. For instance, high crystallinity of cotton cellulose makes it hard to achieve enzymatic or bacterial hydrolysis. In addition, waste textiles are composed of different materials including natural and synthetic fibers, and the cellulosic fibers should be separated from the other materials. Furthermore, presence of dyes and reagents in the fibers can also be challenging in the bioprocessing of textile waste. In the present work, we examined the process of dilute acid hydrolysis of viscose and cotton (i.e. jeans) textiles. Hydrolyses were performed at different lengths of time (8 and 15 min), temperatures (180 and 200 °C), and acid concentrations (0.5, 1.5, and 3% w/w). Hydrolysis of viscose and jeans under identical conditions resulted in significantly different yields of glucose. This may be due to differences in the structure, i.e. high crystalline cellulose in jeans and low crystalline cellulose in viscose.

  • 21.
    Jeihanipour, Azam
    et al.
    University of Borås, School of Engineering.
    Karimi, Keikhosro
    University of Borås, School of Engineering.
    Taherzadeh, Mohammad J.
    University of Borås, School of Engineering.
    Efficient ethanol production from spruce by N-methylmorpholine-N-oxide (NMMO) pretreatment2011Conference paper (Other academic)
    Abstract [en]

    Pretreatment of lignocelluloses with cellulose dissolution reagents is efficient and can be applied under relatively mild conditions. NMMO is an industrial cellulose solvent that can dissolve cellulose by breaking intramolecular bonds. The solvent can be recycled with over 99% recovery and does not produce toxic waste pollutants. After dissolution, the cellulose can be regenerated by fast precipitation with an anti-solvent that is usually water. The dissolution can severely modify the structure of cellulose and reduce its crystallinity, which is very important in hydrolysis of softwoods. Native species of spruce was debarked, cut, milled, and screened to achieve a size of less than 1 mm. The treatment was performed using 85%w/w NMMO solution at 120ºC for 1, 3, and 15 h. The pretreated wood species were then regenerated by addition of boiling distilled water, followed by vacuum filtration and washing. The pretreated and untreated wood species were enzymatically hydrolyzed by commercial cellulase (15 FPU/g) and β-glucosidase (30 IU/g) at 45°C for 96 h. Then, the hydrolyzates were fermented by a flocculation strain of Saccharomyces cerevisiae (CCUG 53310) at 30°C for 24 h. The results showed that the pretreatment, in general, did not significantly affect the composition of the wood, while increased the yield of hydrolysis and fermentation. The cellulose hydrolysis was increased from 11% for native spruce to more than 98% for the wood treated with NMMO for 15 h, and, correspondingly, the yield of ethanol production was increased from 8.1% to over 86.1%.

  • 22.
    Jeihanipour, Azam
    et al.
    University of Borås, Faculty of Textiles, Engineering and Business.
    Zamani, Akram
    University of Borås, Faculty of Textiles, Engineering and Business.
    Karimi, Keikhosro
    University of Borås, Faculty of Textiles, Engineering and Business.
    Taherzadeh, Mohammad
    University of Borås, Faculty of Textiles, Engineering and Business.
    Effect of growing time on the chitosan content of cell wall of zygomycetes fungi2009Conference paper (Other academic)
  • 23.
    Kabir, Maryam M.
    et al.
    University of Borås, School of Engineering.
    Mirahmadi, Kambiz
    Jeihanipour, Azam
    University of Borås, School of Engineering.
    Karimi, Keikhosro
    University of Borås, School of Engineering.
    Taherzadeh, Mohammad
    University of Borås, School of Engineering.
    Effect of sodium hydroxide pretreatment on enzymatic hydrolysis of softwoods and hardwoods2009Conference paper (Other academic)
  • 24.
    Karimi, Keikhosro
    et al.
    University of Borås, School of Engineering.
    Edebo, Lars
    Taherzadeh, Mohammad J.
    University of Borås, School of Engineering.
    Mucor indicus as a biofilter and fermenting organism in continuous ethanol production from lignocellulosic hydrolyzate2008In: Biochemical engineering journal, ISSN 1369-703X, E-ISSN 1873-295X, Vol. 39, no 2, 383-388 p.Article in journal (Refereed)
  • 25.
    Karimi, Keikhosro
    et al.
    Department of Chemical Engineering, Isfahan University of Technology.
    Tabatabaei, Meisam
    Microbial Biotechnology Department, Agricultural Biotechnology Research Institute of Iran (ABRII.
    Sárvári Horváth, Ilona
    University of Borås, Faculty of Textiles, Engineering and Business.
    Kumar, Rajeev
    6 Center for Environmental Research and Technology (CE-CERT), Bourns College of Engineering, University of California.
    Recent trends in acetone, butanol, and ethanol (ABE) production2015In: Biofuel Research Journal, Vol. 2, no 4, 301-308 p.Article in journal (Refereed)
    Abstract [en]

    Among the renewable fuels considered as a suitable substitute to petroleum-based gasoline, butanol has attracted a great deal of attention due to its unique properties. Acetone, butanol, and ethanol (ABE) can be produced biologically from different substrates, including sugars, starch, lignocelluloses, and algae. This process was among the very first biofuel production processes which was commercialized during the First World War. The present review paper discusses the different aspects of the ABE process and the recent progresses made. Moreover, the microorganisms and the biochemistry of the ABE fermentation as well as the feedstocks used are reviewed. Finally, the challenges faced such as low products concentration and products` inhibitory effects on the fermentation are explained and different possible solutions are presented and reviewed.

  • 26. Karimi, Keikhosro
    et al.
    Tabatabaei, Meisam
    Microbial Biotechnology Department, Agricultural Biotechnology Research Institute of Iran (ABRII.
    Sárvári Horváth, Ilona
    University of Borås, Faculty of Textiles, Engineering and Business.
    Kumar, Rajeev
    6 Center for Environmental Research and Technology (CE-CERT), Bourns College of Engineering, University of California.
    Recent trends in acetone, butanol, and ethanol (ABE) production2015In: Biofuel Research Journal, Vol. 2, no 4, 301-308 p.Article in journal (Refereed)
  • 27.
    Karimi, Keikhosro
    et al.
    University of Borås, Faculty of Textiles, Engineering and Business.
    Taherzadeh, Mohammad J
    University of Borås, Faculty of Textiles, Engineering and Business.
    A critical review of analytical methods in pretreatment of lignocelluloses: Composition, imaging, and crystallinity.2016In: Bioresource Technology, ISSN 0960-8524, E-ISSN 1873-2976, Vol. 200Article in journal (Refereed)
    Abstract [en]

    Lignocelluloses are widely investigated as renewable substrates to produce biofuels, e.g., ethanol, methane, hydrogen, and butanol, as well as chemicals such as citric acid, lactic acid, and xanthan gum. However, lignocelluloses have a recalcitrance structure to resist microbial and enzymatic attacks; therefore, many physical, thermal, chemical, and biological pretreatment methods have been developed to open up their structure. The efficiency of these pretreatments was studied using a variety of analytical methods that address their image, composition, crystallinity, degree of polymerization, enzyme adsorption/desorption, and accessibility. This paper presents a critical review of the first three categories of these methods as well as their constraints in various applications. The advantages, drawbacks, approaches, practical details, and some points that should be considered in the experimental methods to reach reliable and promising conclusions are also discussed.

  • 28. Khodaverdi, Mahdi
    et al.
    Jeihanipour, Azam
    Karimi, Keikhosro
    University of Borås, School of Engineering.
    Taherzadeh, Mohammad J.
    University of Borås, School of Engineering.
    Kinetic modeling of rapid enzymatic hydrolysis of crystalline cellulose after pretreatment by NMMO2012In: Journal of Industrial Microbiology and Biotechnology, ISSN 0973-7510, Vol. 39, no 3, 429-438 p.Article in journal (Refereed)
    Abstract [en]

    Pretreatment of cellulose with an industrial cellulosic solvent, N-methylmorpholine-N-oxide, showed promising results in increasing the rate of subsequent enzymatic hydrolysis. Cotton linter was used as high crystalline cellulose. After the pretreatment, the cellulose was almost completely hydrolyzed in less than 12 h, using low enzyme loading (15 FPU/g cellulose). The pretreatment significantly decreased the total crystallinity of cellulose from 7.1 to 3.3, and drastically increased the enzyme adsorption capacity of cellulose by approximately 42 times. A semi-mechanistic model was used to describe the relationship between the cellulose concentration and the enzyme loading. In this model, two reactions for heterogeneous reaction of cellulose to glucose and cellobiose, and a homogenous reaction for cellobiose conversion to glucose was incorporated. The Langmuir model was applied to model the adsorption of cellulase onto the treated cellulose. The competitive inhibition was also considered for the effects of sugar inhibition on the rate of enzymatic hydrolysis. The kinetic parameters of the model were estimated by experimental results and evaluated.

  • 29.
    Lennartsson, Patrik
    et al.
    University of Borås, School of Engineering.
    Karimi, Keikhosro
    University of Borås, School of Engineering.
    Edebo, Lars
    Taherzadeh, Mohammad
    University of Borås, School of Engineering.
    Effects of different growth forms of Mucor indicus on cultivation on dilute-acid lignocellulosic hydrolyzate, inhibitor tolerance, and cell wall composition2009In: Journal of Biotechnology, ISSN 0168-1656, E-ISSN 1873-4863, Vol. 143, no 4, 225-261 p.Article in journal (Refereed)
    Abstract [en]

    The dimorphic fungus Mucor indicus was grown in different forms classified as purely filamentous, mostly filamentous, mostly yeast-like and purely yeast-like, and the relationship between morphology and metabolite production, inhibitor tolerance and the cell wall composition was investigated. Low concentrations of spores in the inoculum with subsequent aeration promoted filamentous growth, whereas higher spore concentrations and anaerobic conditions promoted yeast-like growth. Ethanol was the main metabolite with glycerol next under all conditions tested. The yields of ethanol from glucose were between 0.39 and 0.42 g g−1 with productivities of 3.2–5.0 g l−1 h−1. The ethanol productivity of mostly filamentous cells was increased from 3.9 to 5.0 g l−1 h−1 by the presence of oxygen, whereas aeration of purely yeast-like cells showed no such effect. All growth forms were able to tolerate 4.6 g l−1 furfural and 10 g l−1 acetic acid and assimilate the sugars, although with different consumption rates. The cell wall content of the fungus measured as alkali insoluble materials (AIM) of the purely yeast-like cells was 26% of the biomass, compared to 8% of the pure filaments. However, the chitosan concentration of the filaments was 29% of the AIM, compared to 6% of the yeast-like cells.

  • 30.
    Lennartsson, P.R.
    et al.
    University of Borås, School of Engineering.
    Karimi, K.
    University of Borås, School of Engineering.
    Edebo, L.
    Taherzadeh, M.J.
    University of Borås, School of Engineering.
    Ethanol production by dimorphic fungus Mucor indicus2008Conference paper (Refereed)
  • 31. Lopez, Y
    et al.
    Karimi, K
    University of Borås, School of Engineering.
    Taherzadeh, M.J.
    University of Borås, School of Engineering.
    Martin, C
    Processing of Artisan rice hulls by combining diluce-acid hydrolysis, alkaline delignification, NMMO treatment and enzymatic hydrolysis2011Conference paper (Refereed)
  • 32. Millati, R.
    et al.
    Karimi, K.
    University of Borås, School of Engineering.
    Edebo, L.
    Niklasson, C.
    Taherzadeh, M.J.
    University of Borås, School of Engineering.
    Ethanol production from xylose and wood hydrolyzate by Mucor indicus at different aeration rates2008In: BioResources, ISSN 1930-2126, E-ISSN 1930-2126, Vol. 3, no 4, 1020-1029 p.Article in journal (Refereed)
    Abstract [en]

    The fungus Mucor indicus is able to produce ethanol from xylose as well as dilute-acid lignocellulosic hydrolyzates. The fungus completely assimilated 10 g/L xylose as the sole carbon and energy source within 32 to 65 h at an aeration rate of 0.1 to 1.0 vvm. The highest ethanol yield was 0.16 g/g at 0.1 vvm. Xylitol was formed intermediately with a maximum yield of 0.22 g/g at 0.5 vvm., but disappeared towards the end of experiments. During cultivation in a mixture of xylose and glucose, the fungus did not assimilate xylose as long as glucose was present in the medium. The anaerobic cultivation of the fungus in the hydrolyzate containing 20% xylose and 80% hexoses resulted in no assimilation of xylose but complete consumption of the hexoses in less than 15 h. The ethanol yield was 0.44 g/g. However, the xylose in the hydrolyzate was consumed when the media were aerated at 0.067 to 0.333 vvm. The best ethanol yield was 0.44 g/g at 0.067 vvm. The results of this study suggest that M. indicus hydrolyzate can be first fermented anaerobically for hexose assimilation and subsequently continued under oxygen-limited conditions for xylose fermentation.

  • 33. Mirahmadi, Kambiz
    et al.
    Mohseni Kabir, Maryam
    Jeihanipour, Azam
    University of Borås, School of Engineering.
    Karimi, Keikhosro
    University of Borås, School of Engineering.
    Taherzadeh, Mohammad
    University of Borås, School of Engineering.
    Optimization of sodium hydroxide pretreatment for enzymatic hydrolysis of lignocellulosic materials2009Conference paper (Other academic)
  • 34. Mohsenzadeh, A.
    et al.
    Jeihanipour, A.
    Karimi, K.
    University of Borås, School of Engineering.
    Taherzadeh, M.J.
    University of Borås, School of Engineering.
    Alkali pretreatment of softwood spruce and hardwood birch by NaOH/thiourea, NaOH/urea, NaOH/urea/thiourea, and NaOH/PEG for improve of ethanol and biogas production2012In: Journal of chemical technology and biotechnology (1986), ISSN 0268-2575, E-ISSN 1097-4660, Vol. 87, no 8, 1209-1214 p.Article in journal (Refereed)
    Abstract [en]

    Alkali-dissolution pretreatment of softwood spruce and hardwood birch to improve ethanol and biogas production was investigated. The pretreatments were carried out at different temperatures between − 15 and 80 °C with NaOH/thiourea (7/5.5 wt%), NaOH/urea (7/12 wt%), NaOH/urea/thiourea (7/8/6.5 wt%), and NaOH/PEG (7/1 wt%) aqueous solutions. The pretreated materials were then subjected to enzymatic hydrolysis for 72 h. The pretreatments by NaOH/thiourea at − 15 °C improved the hydrolysis yields of spruce from 11.7% to 57% of theoretical yield, and for birch from 23.1% to 83% of theoretical yield. The enzymatic hydrolysis and fermentation of these pretreated materials by NaOH/thiourea with baker's yeast resulted in 54.0% of theoretical yield compared with 10.9% for untreated spruce and 80.9% of theoretical yield compared with 12.9% for untreated birch. Furthermore, anaerobic digestion of pretreated materials resulted in 0.36 L g−1 VS methane compared with 0.23 L g−1 VS for untreated birch, and 0.21 L g−1 VS compared with 0.03 L g−1 VS for untreated spruce.

  • 35. Mohsenzadeh Syouki, Abas
    et al.
    Jeihanipour, Azam
    University of Borås, School of Engineering.
    Karimi, Keikhosro
    University of Borås, School of Engineering.
    Taherzadeh, Mohammad
    University of Borås, School of Engineering.
    Enhancement of enzymatic hydrolysis of wood by pretreatment with different cellulose dissolution systems2009Conference paper (Other academic)
  • 36. Paraj, A.
    et al.
    Karimi, K.
    University of Borås, School of Engineering.
    Khanahmadi, M.
    Purification of glucoamylase from solid state fermentation media by reverse mycellar system2008Conference paper (Refereed)
  • 37. Paraj, Aliakbar
    et al.
    Khanahmadi, Morteza
    Karimi, Keikhosro
    University of Borås, School of Engineering.
    Taherzadeh, Mohammad J.
    University of Borås, School of Engineering.
    Reverse micellar extraction of fungal glucoamylase produced in solid state fermentation culture2014In: Journal of Microbiology and Biotechnology, ISSN 1017-7825, E-ISSN 1738-8872, in press- p.Article in journal (Refereed)
    Abstract [en]

    Partial purification of glucoamylase from solid-state fermentation culture was, firstly, investigated by reverse micellar extraction (RME). To avoid back extraction problems, the glucoamylase was kept in original aqueous phase, while the other undesired proteins/enzymes were moved to reverse micellar organic phase. The individual and interaction effects of main factors, i.e. pH and NaCl concentration in aqueous phase, and concentration of AOT (sodium bis-2-ethyl-hexyl-sulphosuccinate) in organic phase were studied using response surface methodology. The optimum conditions for the maximum recovery of the enzyme were pH 2.75, 100 mM NaCl, and 200 mM AOT. Furthermore, the optimum organic to aqueous volume ratio (Vorg/Vaq) and appropriate number of sequential extraction stages were 2 and 3, respectively.Finally, 60% of the undesired enzymes including proteases and xylanases were removed from aqueous phase, while 140% of glucoamylase activity was recovered in aqueous phase and the purification factor of glucoamylase was found to be 3.0-fold.

  • 38. Poornejad, Nafiseh
    et al.
    Amin Salehi, S.M.
    Karimi, Keikhosro
    University of Borås, School of Engineering.
    Taherzadeh, Mohammad J.
    University of Borås, School of Engineering.
    Behzad, Tayyebeh
    Improvement of enzymatic hydrolysis of rice straw by Nmethylmorpholine- N-oxide (NMMO) pretreatment2011In: WREC11 World Renewable Energy Conference 2011, Linköping University Electronic Press , 2011, 1-5 p.Conference paper (Refereed)
  • 39. Poornejad, Nafiseh
    et al.
    Karimi, Keikhosro
    University of Borås, School of Engineering.
    Salehi, S.M Amin
    Taherzadeh, Mohammad J.
    University of Borås, School of Engineering.
    Improvement of Ethanol Production from Spruce by Solvent Pretreatment2010Conference paper (Other academic)
    Abstract [en]

    Lignocelluloses are abundant and inexpensive resources that can be used for production of bioethanol. However, these materials, especially softwoods, are resistant to enzymatic hydrolysis and a pretreatment process is necessary for efficient conversion to ethanol. The pretreatment is intended to render the cellulose amenable to enzymatic hydrolysis and subsequent fermentation to bioethanol. Several methods has been suggested for the pretreatment of lignocelluloses. The pretreatment with cellulose solvents are among the promising methods since they can perform in mild processing conditions. N-Methylmorpholine-N-oxide (NMMO) is among the industrial solvents which can dissolve cellulose by breaking intermolecular interactions. NMMO is nowadays used in the industrial Lyocell process, which is one of the modern and environmentally friendly industrial fiber-making technologies. It does not produce any toxic waste pollutants, and can be recovered over 98%. The pretreatment of lignocellulose by NMMO can modify the crystal structure of cellulose. In the current work a commercial grade 50% (W/W) NMMO solution was used for pretreatment of spruce. The NMMO solution was concentrated by vacuum evaporation to 85% NMMO. The pretreatment performed at 120ºC for 3 h. The pretreated wood species were then regenerated by addition of boiling distilled water, followed by vacuum filtration and washing. The pretreated and untreated spruce species were enzymatically hydrolyzed by commercial cellulase (celluclast 1.5L, Novozyme, Denmark) and Β-glucosidase (Novozyme 188, Novozyme, Denmark) at 45ºC for 96h. A thermotolerant strain of Saccharomyces cerevisiae was used for fermentation. Inoculum was aerobically cultivated at 30 °C and 120 rpm for 24 h. The enzymatic hydrolyzate was supplemented with necessary nutrient and fermented by the yeast for 24h at 30 °C and 120 rpm. The liquid samples were analyzed by HPLC. The results showed that the yield of ethanol increased from 7.2 g/g to 77 g/g, when the wood treated with the solvent. Formation of glycerol and other metabolites were also detected and discussed. It can be concluded that the method can be a promising alternative for pretreatment of softwoods for bioethanol production.

  • 40. Rahim Labafzadeh, Sara
    et al.
    Jafari, Vahid
    Jeihanipour, Azam
    University of Borås, School of Engineering.
    Karimi, Keikhosro
    University of Borås, School of Engineering.
    Taherzadeh, Mohammad
    University of Borås, School of Engineering.
    Conversion of Prevalent Building Waste to Ethanol2009Conference paper (Other academic)
  • 41. Rodríquez, Emir Cabrera
    et al.
    Karimi, Keikhosro
    University of Borås, School of Engineering.
    Curbelo, Caridad
    Taherzadeh, Mohammad J.
    University of Borås, School of Engineering.
    Improvement of Enzymatic Hydrolysis of Spruce by Sodium Hydroxide Pretreatment at Low Temperature2010Conference paper (Other academic)
    Abstract [en]

    The supply of fermentable sugars is likely to be a limiting factor for large-scale production of biofuels such as bioethanol. Therefore, processes are being developed to produce sugars from lignocellulose material by enzymatic hydrolysis. However, the cellulose fraction of lignocelluloses are not readily accessible for the hydrolyzing enzymes. Efficient hydrolysis of lignocelluloses requires pretreatment, since these materials are resistant to enzymatic hydrolysis. Several processes have been investigated for this pretreatment, in which alkali processes are among the promissing methods. In the current work, effect of NaOH pretreatment of spruce on the chemical composition and the subsequent enzymatic hydrolysis was investigated. Native spruce specie (Picea abies) was obtained from the forest around the city of Borås in Sweden. They were debarked and ball milled. The wood species was analyzed for carbohydrate and lignin fractions according to NREL methods. The wood species was chemically pretreated using 7% sodium hydroxide solution with 5% solid content at 0°C for 30, 60, 120 and 180 minutes. After the pretreatment, the residual solids were washed with distilled water to remove chemicals and neutralized to pH 7. The neutralized samples were filtered and stored for subsequent hydrolysis. Enzymatic hydrolysis of the pretreated wood was carried out at pH 4.8, 45°C and 5% dry substances. Commercial enzymes, cellulase (Celluclast 1.5L, Novozyme, Denmark) and β- glucosidase (Novozyme 188, Novozyme, Denmark) were used in the enzymatic hydrolysis. 30 FPU cellulase and 50 IU b-glucosidase per grams of the wood species were used for enzymatic hydrolysis. The pretreatments resulted in changes on the composition of the material. There were less than 1% losses in carbohydrate, suggesting no significant carbohydrate hydrolysis. Xylans were the most affected components by the pretreatments. The largest xylan removal was almost 50%, and it was occurred by using sodium hydroxide solution for 180 minutes. The profile of released sugars were also analyzed and compared. Significant improvement on the yield of enzymatic hydrolysis was observed as a results of the pretreatment.

  • 42. Shafiei, M.
    et al.
    Karimi, K.
    University of Borås, School of Engineering.
    Zilouei, H.
    Taherzadeh, M.J.
    University of Borås, School of Engineering.
    Economic impact of NMMO pretreatment on ethanol and biogas production from pinewood2014In: BioMed Research International, ISSN 2314-6133, E-ISSN 2314-6141, Vol. 2014Article in journal (Refereed)
    Abstract [en]

    Processes for production of ethanol and biogas (scenario 1) and biomethane (scenario 2) from pinewood improved by N - methyl morpholine - N - oxide ( NMMO) pretreatnment were developed and simulated by Aspen plus®.These processes were compared with t wo processes using steam explosion instead of N - methyl morpholine - N - oxide ( NMMO) pretreatment for production of ethanol (scenario 3) and biomethane (scenario 4), and the econom ies of these four processes were evaluated by Aspen Process Economic Analyzer ( PEA ). The gasoline equivalent prices of the products including 25% value added tax ( VAT ) and selling and distribution expenses for the scenarios 1 to 4 were respectively 1.40, 1 .20, 1.24, and 1.04 €/l, which are lower than gasoline price (1.65 €/l average in 2013 in Sweden). The profitability indexes for the scenarios 1 to 4 were 1.14, 0.93, 1.16, and 0.96 , respectively. Despite the lower manufacturing costs of biomethane, the pr ofitability indexes of these processes were lower than that of the bioethanol processes, because of higher capital requirements. The results showed that taxing rule is an effective parameter on the economy of the biofuels. The gasoline equivalent prices of the biofuels were 18 - 39% lower than gasoline; however, 37% of the gasoline price contributes to ene rgy and carbon dioxide tax which are not included in the prices of biofuels based on the Swedish taxation rules .

  • 43. Shafiei, M
    et al.
    Karimi, Keikhosro
    University of Borås, School of Engineering.
    Taherzadeh, Mohammad
    University of Borås, School of Engineering.
    Ethanol production by flocculating Saccharomyces cerevisiae2009Conference paper (Other academic)
  • 44. Shafiei, M.
    et al.
    Ziluoei, H.
    Zamani, A.
    Taherzadeh, M.J.
    University of Borås, School of Engineering.
    Karimi, K.
    University of Borås, School of Engineering.
    Enhancement of ethanol production from spruce wood chips by ionic liquid pretreatment2013In: Applied Energy, ISSN 0306-2619, E-ISSN 1872-9118, Vol. 102, 163-169 p.Article in journal (Refereed)
    Abstract [en]

    Pretreatment with three green cellulose solvents, N-methylmorpholine-N-oxide (NMMO), 1-ethyl-3-methylimidazolium acetate ([EMIM][OAc]), and 1-butyl-3-methylimidazolium acetate ([BMIM][OAc]) were used for improvement of ethanol production. Spruce chips and powder were pretreated at 120 °C for 1, 3, and 15 h. In order to investigate the efficiency of the pretreatments, the pretreated materials were subjected to enzymatic hydrolysis at 45 °C for 72 h, followed by fermentation with Saccharomyces cerevisiae at 32 °C for 24 h. The best results were obtained from 15 h pretreatment with [EMIM][OAc]. The ethanol yield from the untreated spruce chips and powder were 2.7% and 9.7% of the maximum theoretical yield, respectively, whereas pretreatment of these materials with [EMIM][OAc] improved the ethanol yield to 66.8% and 81.5%, respectively.

  • 45. Shafiei, Marzieh
    et al.
    Karimi, Keikhosro
    University of Borås, School of Engineering.
    Taherzadeh, Mohammad J.
    University of Borås, School of Engineering.
    Palm Date Fibers: Analysis and Enzymatic Hydrolysis2010In: International Journal of Molecular Sciences, ISSN 1422-0067, E-ISSN 1422-0067, Vol. 11, no 11, 4285-4296 p.Article in journal (Refereed)
    Abstract [en]

    Waste palm dates were subjected to analysis for composition and enzymatic hydrolysis of their flesh fibers. The fruit contained 32% glucose and 30% fructose, while the water-insoluble fibers of its flesh consisted of 49.9% lignin and 20.9% polysaccharides. Water-insoluble fibers were settled to 55% of its initial volume in 12 h. The presence of skin and flesh colloidal fibers results in high viscosity and clogging problems during industrial processes. The settling velocity of the fibers was improved by enzymatic hydrolysis. Hydrolysis resulted in 84.3% conversion of the cellulosic part of the fibers as well as reducing the settling time to 10 minutes and the final settled volume to 4% of the initial volume. It implies easier separation of the fibers and facilitates fermentation processes in the corresponding industries. Two kinds of high- and low-lignin fibers were identified from the water-insoluble fibers. The high-lignin fibers (75% lignin) settled easily, while the low-lignin fibers (41.4% lignin) formed a slurry suspension which settled very slowly. The hydrophilicity of these low-lignin fibers is the major challenge of the industrial processes.

  • 46. Shafiei, Marzieh
    et al.
    Karimi, Keikhosro
    University of Borås, School of Engineering.
    Taherzadeh, Mohammad J.
    University of Borås, School of Engineering.
    Techno-economic study of ethanol from spruce by N-methylmorpholine-N-oxide (NMMO) pretreatment2011Conference paper (Other academic)
    Abstract [en]

    Pretreatment is necessary to open up the crystalline structure of the cellulose fibers. It is believed that pretreatment is a “key process” to have an economically feasible ethanol production from lignocelluloses. N-methylmorphilne-N-oxide (NMMO) is a cellulose solvent, which has an industrial application in viscose process for fiber production. NMMO does not produce any toxic waste pollutant and is an environmentally friendly solvent. Considering NMMO as a promising alternative for pretreatment of wood, a novel process for ethanol production from wood was developed in this work. Wood is pretreated by concentrated NMMO and ethanol is produced by NSSF process. Biogas and solid residues are the valuable by products of this process. Simulation of the process with Aspen Plus® was applied to solve the process mass and energy balance; finding the bottlenecks of the process, optimizing the equipment configuration, and providing the necessary data for the equipment design. The economical feasibility of the developed biorefinery for five different plant capacities was studied by Aspen Icarus Process Evaluator®. The base case was designed to utilize 200,000 tons of spruce wood per year and needed M€ 58.3 as total capital investment. Ethanol production yield, based on experiments, was as high as one liter of ethanol per 4 kilograms of wood. Effect of price of feedstock, enzyme, methane, carbon dioxide and solid residue as well as nutrient load on the production cost were investigated.

  • 47. Shafiei, Marzieh
    et al.
    Karimi, Keikhosro
    University of Borås, School of Engineering.
    Taherzadeh, Mohammad J.
    University of Borås, School of Engineering.
    Techno-economical study of ethanol and biogas from spruce wood by NMMO-pretreatment and rapid fermentation and digestion2011In: Bioresource Technology, ISSN 0960-8524, E-ISSN 1873-2976, Vol. 102, no 17, 7879-7886 p.Article in journal (Refereed)
    Abstract [en]

    Given that N-methylmorpholine-N-oxide (NMMO) is a promising alternative for the pretreatment of lignocelluloses, a novel process for ethanol and biogas production from wood was developed. The solvent, NMMO, is concentrated by multistage evaporation, and the wood is pretreated with the concentrated NMMO. Thereafter, ethanol is produced by the non-isothermal simultaneous saccharification and fermentation (NSSF) method, which is a rapid and efficient process. The wastewater is treated by upflow anaerobic sludge blanket (UASB) digester for rapid production of biogas. The process was simulated by Aspen plus®. Using mechanical vapor recompression for evaporators in the pretreatment and multi-pressure distillation columns, the energy requirements for the process were minimized. The economical feasibility of the developed biorefinery for five different plant capacities was studied by Aspen Icarus Process Evaluator. The base case was designed to utilize 200,000 tons of spruce wood per year and required M€ 58.3 as the total capital investment, while the production cost of ethanol is calculated to be €/l 0.44.

  • 48. Shafiei, Marzieh
    et al.
    Karimi, Keikhosro
    University of Borås, School of Engineering.
    Zilouei, Hamid
    Taherzadeh, Mohammad J.
    University of Borås, School of Engineering.
    Enhanced Ethanol and Biogas Production from Pinewood by NMMO Pretreatment and Detailed Biomass Analysis2014In: BioMed Research International, ISSN 2314-6133, E-ISSN 2314-6141, Vol. 2014, no Article ID 469378Article in journal (Refereed)
    Abstract [en]

    N-Methyl morpholine-N-oxide (NMMO) is an environmentally friendly and commercially applied cellulose solvent that is suggested for pretreatment of lignocelluloses to improve biofuel productions. However, the underlying mechanisms of the improvements have been poorly understood yet. In an attempt to investigate the mechanisms, pinewood powder and chips were pretreated with 85% (w/w) NMMO at 120°C for 1–15 h. The pretreatment improved ethanol production yield from 7.2% (g/g) for the untreated wood powder to 68.1–86.1% (g/g) and from 1.7% (g/g) for the untreated wood chips to 12.6–51.2% (g/g) of theoretical yield. Similarly, the biogas yields of untreated wood chips and powder were improved from 21 and 66 (mL/g volatile solids) by 3.5–6.8- and 2.6–3.4-folds, respectively. SEM micrographs indicated major increase in the wood porosity by the pretreatment, which would confirm increase in the water swelling capacity as well as enzyme adsorption. The analysis of X-ray diffraction showed considerable reduction in the cellulose crystallinity by the pretreatment, while FTIR spectroscopy results indicated reduction of lignin on the wood surface by the pretreatment.

  • 49. Sharifia, Mahnaz
    et al.
    Karimi, Keikhosro
    University of Borås, School of Engineering.
    Taherzadeh, Mohammad J.
    University of Borås, School of Engineering.
    Ethanol and chitosan from glucose, fructose, and sucrose by dimorphism fungus Mucor indicus2007Conference paper (Refereed)
  • 50.
    Sharifia, Mahnaz
    et al.
    University of Borås, School of Engineering.
    Karimi, Keikhosro
    University of Borås, School of Engineering.
    Taherzadeh, Mohammad J
    University of Borås, School of Engineering.
    Production of ethanol by filamentous and yeast-like forms of Mucor indicus from fructose, glucose, sucrose and molasses2008In: Journal of Industrial Microbiology & Biotechnology, ISSN 1367-5435, E-ISSN 1476-5535, Vol. 35, no 11, 1253-1259 p.Article in journal (Refereed)
    Abstract [en]

    The fungus Mucor indicus is found in this study able to consume glucose and fructose, but not sucrose in fermentation of sugarcane and sugar beet molasses. This might be an advantage in industries which want to selectively remove glucose and fructose for crystallisation of sucrose present in the molasses. On the other hand, the fungus assimilated sucrose after hydrolysis by the enzyme invertase. The fungus efficiently grew on glucose and fructose and produced ethanol in synthetic media or from molasses. The cultivations were carried out aerobically and anaerobically, and manipulated toward filamentous or yeast-like morphology. Ethanol was the major metabolite in all the experiments. The ethanol yield in anaerobic cultivations was between 0.35 and 0.48 g/g sugars consumed, depending on the carbon source and the growth morphology, while a yield of as low as 0.16 g/g was obtained during aerobic cultivation. The yeast-like form of the fungus showed faster ethanol production with an average productivity of 0.90 g/l h from glucose, fructose and inverted sucrose, than the filamentous form with an average productivity of 0.33 g/l h. The biomass of the fungus was also analyzed with respect to alkali-insoluble material (AIM), chitin, and chitosan. The biomass of the fungus contained per g maximum 0.217 g AIM and 0.042 g chitosan in yeast-like cultivation under aerobic conditions.

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