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  • 1.
    Carvalho, Lara
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science.
    Furusjö, Erik
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science.
    Kirtania, Kawnish
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science.
    Wetterlund, Elisabeth
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science.
    Lundgren, Joakim
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science.
    Anheden, Marie
    Innventia AB.
    Wolf, Jens
    Innventia AB.
    Techno-economic assessment of catalytic gasification of biomass powders for methanol production2017In: Bioresource Technology, ISSN 0960-8524, E-ISSN 1873-2976, Vol. 237, p. 167-177Article in journal (Refereed)
    Abstract [en]

    This study evaluated the techno-economic performance and potential benefits of methanol production through catalytic gasification of forest residues and lignin. The results showed that while catalytic gasification enables increased cold gas efficiencies and methanol yields compared to non-catalytic gasification, the additional pre-treatment energy and loss of electricity production result in small or no system efficiency improvements. The resulting required methanol selling prices (90-130 €/MWh) are comparable with production costs for other biofuels. It is concluded that catalytic gasification of forest residues can be an attractive option as it provides operational advantages at production costs comparable to non-catalytic gasification. The addition of lignin would require lignin costs below 25 €/MWh to be economically beneficial.

  • 2. Christakopoulos, Paul
    et al.
    Koullas, D.P.
    National Technical University of Athens.
    Kekos, D.
    National Technical University of Athens.
    Koukios, E.G.
    National Technical University of Athens.
    Macris, B.J.
    National Technical University of Athens.
    Direct ethanol conversion of pretreated straw by Fusarium oxysporum1991In: Bioresource Technology, ISSN 0960-8524, E-ISSN 1873-2976, Vol. 35, no 3, p. 297-300Article in journal (Refereed)
    Abstract [en]

    Factors affecting the direct conversion of alkali pretreated straw to ethanol by Fusarium oxysporum F3 were investigated and the alkali level used for pretreatment and the degree of delignification of straw were found to be the most important. A linear correlation between ethanol yield and both the degree of straw delignification and the alkali level was observed. At optimum delignified straw concentration (4% w/v), a maximum ethanol yield of 0·275 g ethanol g−1 of straw was obtained corresponding to 67·8% of the theoretical yield.

  • 3. Christakopoulos, Paul
    et al.
    Li, Lian-Wu
    National Technical University of Athens.
    Kekos, Dimitris
    National Technical University of Athens.
    Macris, Basil J.
    National Technical University of Athens.
    Direct conversion of sorghum carbohydrates to ethanol by a mixed microbial culture1993In: Bioresource Technology, ISSN 0960-8524, E-ISSN 1873-2976, Vol. 45, no 2, p. 89-92Article in journal (Refereed)
    Abstract [en]

    The carbohydrates of sweet sorghum were directly converted to ethanol by a mixed culture of Fusarium oxysporum F3 and Saccharomyces cerevisiae 2541. A number of factors affecting this bioconversion was studied. Optimum ethanol yields of 33·2 g/100 g of total sorghum carbohydrates, corresponding to 10·3 g/100 g of fresh stalks, were obtained. These values represented 68·6% of the theoretical yield based on total polysaccharides and exceeded that based on oligosaccharides of sorghum by 53·7%. The results demonstrated that more than half of the sorghum polysaccharides were directly fermented to ethanol, thus making the process worthy of further investigation.

  • 4. Christakopoulos, Paul
    et al.
    Mamma, D.
    National Technical University of Athens.
    Nerinckx, W.
    University of Ghent.
    Kekos, D.
    National Technical University of Athens.
    Macris, B.
    National Technical University of Athens.
    Claeyssens, M.
    University of Ghent.
    Production and partial characterization of xylanase from Fusarium oxysporum1996In: Bioresource Technology, ISSN 0960-8524, E-ISSN 1873-2976, Vol. 58, no 2, p. 115-119Article in journal (Refereed)
    Abstract [en]

    Production of xylanase by Fusarium oxysporum strain F3 was enhanced by optimization of initial pH of the culture medium, the type and concentration of nitrogen and carbon source, and the growth temperature. Under these conditions, yields as high as 245 U/ml of culture medium were obtained. The most important characteristic of the enzyme is its high pH stability. It retained 80 and 66% of the activity at pH 9.0 after 24 h at 4 and 30°C, respectively. Chromogenic (fluorogenic) 4-methylumbelliferyl-β-glycosides of xylose (MUX) and xylobiose (MUX2) were used to characterize xylanase multienzyme components, after separation by isoelectric focusing. The zymogram indicated one major, one minor xylanase and one active β-xylosidase exhibiting pI values of 9.5, 6.5 and 3.8, respectively

  • 5.
    Dimarogona, Maria
    et al.
    Biotechnology Laboratory, School of Chemical Engineering, National Technical University of Athens.
    Topakas, Evangelos
    Biotechnology Laboratory, School of Chemical Engineering, National Technical University of Athens.
    Olsson, Lisbeth
    Chalmers University of Technology.
    Christakopoulos, Paul
    Lignin boosts the cellulase performance of a GH-61 enzyme from Sporotrichum thermophile2012In: Bioresource Technology, ISSN 0960-8524, E-ISSN 1873-2976, Vol. 110, p. 480-487Article in journal (Refereed)
    Abstract [en]

    An enzyme belonging to the glycoside hydrolase family 61 from the thermophilic fungus Sporotrichum thermophile, was functionally expressed in the methylotrophic yeast Pichia pastoris under the transcriptional control of the alcohol oxidase (AOX1) promoter. The enzyme hydrolyzed barley β-glucan, carboxymethyl cellulose, lichenan, wheat arabinoxylan and birchwood xylan showing optimal activity at pH 8 and 65 °C. A 2:1 mixture of Celluclast 1.5 L and StCel61a was capable of increasing the degree of spruce conversion by 42%. The use of substrates with varying lignin content permitted the detection of a dependence of the enhancing capacity of StCel61a on the radical scavenging capacity of the different lignocellulosics. In the presence of a reductant, StCel61a boosted the efficiency of a mixture of purified cellulases (EGII, CBHI, β-GLUC) by 20%. The synergistic activity exhibited by StCel61a and its dependence on reducing substances provide guidelines for process design towards the production of economically viable bioethanol.

  • 6.
    Eriksson, Daniel
    et al.
    Swedish University of Agricultural Sciences, Vindeln Experimental Forest, Svartberget Research Station.
    Weiland, Fredrik
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science.
    Hedman, Henry
    Energy Technology Centre, Piteå.
    Stenberg, Martin
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science.
    Öhrman, Olov
    Lestander, Torbjörn A.
    Swedish University of Agricultural Sciences, Unit of Biomass Technology and Chemistry, Umeå.
    Bergsten, Urban
    Swedish University of Agricultural Sciences, Vindeln Experimental Forest, Svartberget Research Station.
    Öhman, Marcus
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science.
    Characterization of Scots pine stump-root biomass as feed-stock for gasification2012In: Bioresource Technology, ISSN 0960-8524, E-ISSN 1873-2976, Vol. 104, p. 729-736Article in journal (Refereed)
    Abstract [en]

    The main objective was to explore the potential for gasifying Scots pine stump-root biomass (SRB). Washed thin roots, coarse roots, stump heartwood and stump sapwood were characterized (solid wood, milling and powder characteristics) before and during industrial processing. Non-slagging gasification of the SRB fuels and a reference stem wood was successful, and the gasification parameters (synthesis gas and bottom ash characteristics) were similar. However, the heartwood fuel had high levels of extractives (≈ 19%) compared to the other fuels (2 – 8%) and thereby ≈ 16% higher energy contents but caused disturbances during milling, storage, feeding and gasification. SRB fuels could be sorted automatically according to their extractives and moisture contents using near-infrared spectroscopy, and their amounts and quality in forests can be predicted using routinely collected stand data, biomass functions and drill core analyses. Thus, SRB gasification has great potential and the proposed characterizations exploit it.

  • 7. Grimm, Alejandro
    et al.
    Zanzi, Rolando
    Department of Chemical Engineering and Technology, Division of Chemical Reaction Engineering, Royal Institute of Technology (KTH).
    Björnbom, Emilia
    Department of Chemical Engineering and Technology, Division of Chemical Reaction Engineering, Royal Institute of Technology (KTH).
    Cukierman, Ana Lea
    Programa de Investigación y Desarrollo de Fuentes Alternativas de Materias Primas y Energía (PINMATE), Universidad de Buenos Aires, Argentina.
    Comparison of different types of biomasses for copper biosorption2007In: Bioresource Technology, ISSN 0960-8524, E-ISSN 1873-2976, Vol. 99, p. 2559-2565Article in journal (Refereed)
  • 8.
    Helmerius, Jonas
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Sustainable Process Engineering.
    Walter, Jonas Vinblad von
    Luleå tekniska universitet.
    Rova, Ulrika
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Sustainable Process Engineering.
    Berglund, Kris
    Hodge, David B.
    Department of Chemical Engineering and Materials Science, Michigan State University, East Lansing.
    Impact of hemicellulose pre-extraction for bioconversion on birch Kraft pulp properties2010In: Bioresource Technology, ISSN 0960-8524, E-ISSN 1873-2976, Vol. 101, no 15, p. 5996-6005Article in journal (Refereed)
    Abstract [en]

    The combination of hemicellulose extraction with chemical pulping processes is one approach to generate a sugar feedstock amenable to biochemical transformation to fuels and chemicals. Extractions of hemicellulose from silver birch (Betula pendula) wood chips using either water or Kraft white liquor (NaOH, Na2S, and Na2CO3) were performed under conditions compatible with Kraft pulping, using times ranging between 20 and 90 min, temperatures of 130-160 °C, and effective alkali (EA) charges of 0-7%. The chips from select extractions were subjected to subsequent Kraft pulping and the refined pulps were made into handsheets. Several metrics for handsheet strength properties were compared with a reference pulp made without an extraction step. This study demonstrated that white liquor can be utilized to extract xylan from birch wood chips prior to Kraft cooking without decreasing the pulp yield and paper strength properties, while simultaneously impregnating cooking alkali into the wood chips. However, for the alkaline conditions tested extractions above pH 10 resulted in low concentrations of xylan. Water extractions resulted in the highest final concentrations of xylan; yielding a liquor without the presence of toxic or inhibitory inorganics and minimal soluble aromatics that we demonstrate can be successfully enzymatically hydrolyzed to monomeric xylose and fermented to succinic acid. However, water extractions were found to negatively impact some pulp properties including decreases in compression strength, bursting strength, tensile strength, and tensile stiffness while exhibiting minimal impact on elongation and slight improvement in tearing strength index.

  • 9. Hodge, David
    et al.
    Karim, M.N.
    Texas Tech University, Lubbock.
    Schell, D.J.
    National Bioenergy Center, National Renewable Energy Laboratory, Golden, CO.
    McMillan, J.D.
    National Bioenergy Center, National Renewable Energy Laboratory, Golden, CO.
    Soluble and insoluble solids contributions to high-solids enzymatic hydrolysis of lignocellulose2008In: Bioresource Technology, ISSN 0960-8524, E-ISSN 1873-2976, Vol. 99, no 18, p. 8940-8948Article in journal (Refereed)
    Abstract [en]

    The rates and extents of enzymatic cellulose hydrolysis of dilute acid pretreated corn stover (PCS) decline with increasing slurry concentration. However, mass transfer limitations are not apparent until insoluble solids concentrations approach 20% w/w, indicating that inhibition of enzyme hydrolysis at lower solids concentrations is primarily due to soluble components. Consequently, the inhibitory effects of pH-adjusted pretreatment liquor on the enzymatic hydrolysis of PCS were investigated. A response surface methodology (RSM) was applied to empirically model how hydrolysis performance varied as a function of enzyme loading (12-40 mg protein/g cellulose) and insoluble solids concentration (5-13%) in full-slurry hydrolyzates. Factorial design and analysis of variance (ANOVA) were also used to assess the contribution of the major classes of soluble components (acetic acid, phenolics, furans, sugars) to total inhibition. High sugar concentrations (130 g/L total initial background sugars) were shown to be the primary cause of performance inhibition, with acetic acid (15 g/L) only slightly inhibiting enzymatic hydrolysis and phenolic compounds (9 g/L total including vanillin, syringaldehyde, and 4-hydroxycinnamic acid) and furans (8 g/L total of furfural and hydroxymethylfurfural, HMF) with only a minor effect on reaction kinetics. It was also demonstrated that this enzyme inhibition in high-solids PCS slurries can be approximated using a synthetic hydrolyzate composed of pure sugars supplemented with a mixture of acetic acid, furans, and phenolic compounds, which indicates that generally all of the reaction rate-determining soluble compounds for this system can be approximated synthetically.

  • 10.
    Kalantzi, Styliani
    et al.
    National Technical University of Athens.
    Mamma, Diomi
    National Technical University of Athens.
    Christakopoulos, Paul
    Kekos, Dimitris
    National Technical University of Athens.
    Effect of pectate lyase bioscouring on physical, chemical and low-stress mechanical properties of cotton fabrics2008In: Bioresource Technology, ISSN 0960-8524, E-ISSN 1873-2976, Vol. 99, no 17, p. 8185-8192Article in journal (Refereed)
    Abstract [en]

    The main objective of the present study was to meticulously investigate an inclusive set of physicochemical and handle properties (determined through Kawabata evaluation system) of bioscoured cotton fabrics. The application of a commercial pectinase preparation, Bioprep 3000L, for a range of concentrations and treatment times, could create a pectin-free textile with low wax content. Multiple regression analysis was used to describe the effect of enzymatic process variables on pectin and waxes removal.Comparison of fabrics’ properties such as wettability, whiteness, crystallinity index, and dyeing behaviour, confirmed that bioscouring could be as much effective as the conventional alkaline process. Uncovering the relationship between the composition of materials and their physicochemical properties was attempted. The application of higher enzyme concentrations generated fabrics with improved low-stress mechanical properties. Bending and shear rigidity, compressional resilience, as well as, extensibility of enzymatically treated cotton fabrics could be efficiently predicted by means of a single independent variable, the crystallinity index.

  • 11.
    Kalogeris, E
    et al.
    Biosystems Technology Laboratory, Chemical Engineering Department, National Technical University of Athens.
    Iniotaki, F
    Biosystems Technology Laboratory, Chemical Engineering Department, National Technical University of Athens.
    Topakas, E
    Biosystems Technology Laboratory, Chemical Engineering Department, National Technical University of Athens.
    Christakopoulos, Paul
    Kekos, D
    Biosystems Technology Laboratory, Chemical Engineering Department, National Technical University of Athens.
    Macris, B.J
    Biosystems Technology Laboratory, Chemical Engineering Department, National Technical University of Athens.
    Performance of an intermittent agitation rotating drum type bioreactor for solid-state fermentation of wheat straw2003In: Bioresource Technology, ISSN 0960-8524, E-ISSN 1873-2976, Vol. 86, no 3, p. 207-213Article in journal (Refereed)
    Abstract [en]

    A laboratory bioreactor, designed for solid-state fermentation of thermophilic microorganisms, was operated for production of cellulases and hemicellulases by the thermophilic fungus Thermoascus aurantiacus. The suitability of the apparatus for the effective control of important operating variables affecting growth of microbes in solid-state cultivation was determined. Application of the optimum conditions found for the moisture content of the medium, growth temperature and airflow rate produced enzyme yields of 1709 U endoglucanase, 4 U cellobiohydrolase, 79 U β-glucosidase, 5.5 U FPA, 4490 U xylanase and 45 U β-xylosidase per g of dry wheat straw. The correlation between microorganism growth and production of enzymes was efficiently described by the Le Duy kinetic model. © 2002 Elsevier Science Ltd. All rights reserved.

  • 12.
    Karnaouri, Anthi C.
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Chemical Engineering.
    Antonopoulou, Io
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Chemical Engineering.
    Zerva, Anastasia
    Biotechnology Laboratory, Department of Synthesis and Development of Industrial Processes, School of Chemical Engineering, National Technical University of Athens, Athens, Greece.
    Dimarogona, Maria
    Section of Process and Environmental Engineering, Department of Chemical Engineering, University of Patras, Patras, Greece.
    Topakas, Evangelos
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Chemical Engineering. Biotechnology Laboratory, Department of Synthesis and Development of Industrial Processes, School of Chemical Engineering, National Technical University of Athens, Athens, Greece.
    Rova, Ulrika
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Chemical Engineering.
    Christakopoulos, Paul
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Chemical Engineering.
    Thermophilic enzyme systems for efficient conversion of lignocellulose to valuable products: Structural insights and future perspectives for esterases and oxidative catalysts2019In: Bioresource Technology, ISSN 0960-8524, E-ISSN 1873-2976, Vol. 279, p. 362-372Article in journal (Refereed)
    Abstract [en]

    Thermophilic enzyme systems are of major importance nowadays in all industrial processes due to their great performance at elevated temperatures. In the present review, an overview of the current knowledge on the properties of thermophilic and thermotolerant carbohydrate esterases and oxidative enzymes with great thermostability is provided, with respect to their potential use in biotechnological applications. A special focus is given to the lytic polysaccharide monooxygenases that are able to oxidatively cleave lignocellulose through the use of oxygen or hydrogen peroxide as co-substrate and a reducing agent as electron donor. Structural characteristics of the enzymes, including active site conformation and surface properties are discussed and correlated with their substrate specificity and thermostability properties.

  • 13.
    Katsimpouras, Constantinos
    et al.
    Industrial Biotechnology & Biocatalysis Group, Biotechnology Laboratory, School of Chemical Engineering, National Technical University of Athens.
    Dedes, Grigorios
    Industrial Biotechnology & Biocatalysis Group, Biotechnology Laboratory, School of Chemical Engineering, National Technical University of Athens.
    Bistis, Perrakis
    Industrial Biotechnology & Biocatalysis Group, Biotechnology Laboratory, School of Chemical Engineering, National Technical University of Athens.
    Kekos, Dimitrios
    Industrial Biotechnology & Biocatalysis Group, Biotechnology Laboratory, School of Chemical Engineering, National Technical University of Athens.
    Kalogiannis, Konstantinos G.
    Chemical Process and Energy Resources Institute (CPERI) .
    Topakas, Evangelos
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Chemical Engineering. Industrial Biotechnology & Biocatalysis Group, Biotechnology Laboratory, School of Chemical Engineering, National Technical University of Athens.
    Acetone/water oxidation of corn stover for the production of bioethanol and prebiotic oligosaccharides2018In: Bioresource Technology, ISSN 0960-8524, E-ISSN 1873-2976, Vol. 270, p. 208-215Article in journal (Refereed)
    Abstract [en]

    Ethanol production at high-gravity promise to achieve concentrations over the threshold for an economical distillation process and concurrently reduce water consumption. However, a persisting limitation is the poor mass transfer conditions resulting in low ethanol yields and concentrations. Hereby, the combination of an acetone/water oxidation pretreatment process (AWO) with a liquefaction/saccharification step, using a free-fall mixer, before simultaneous saccharification and fermentation (SSF) can realize ethanol concentrations of up to ca. 74 g/L at a solids content of 20 wt.%. The free-fall mixer achieved a biomass slurry’s viscosity reduction by 87 % after only 2 h of enzymatic saccharification, indicating the efficiency of the mixing system. Furthermore, the direct enzymatic treatment of AWO pretreated corn stover (CS) by a GH11 recombinant xylanase, led to the production of xylooligosaccharides (XOS) with prebiotic potential and the removal of insoluble fibers of hemicellulose improved the glucose release of AWOCS by 22 %.

  • 14.
    Katsimpouras, Constantinos
    et al.
    Industrial Biotechnology & Biocatalysis Group, School of Chemical Engineering, National Technical University of Athens.
    Zacharopoulou, Maria
    Industrial Biotechnology & Biocatalysis Group, School of Chemical Engineering, National Technical University of Athens.
    Matsakas, Leonidas
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Chemical Engineering.
    Rova, Ulrika
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Chemical Engineering.
    Christakopoulos, Paul
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Chemical Engineering.
    Topakas, Evangelos
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Chemical Engineering. Industrial Biotechnology & Biocatalysis Group, School of Chemical Engineering, National Technical University of Athens.
    Sequential high gravity ethanol fermentation and anaerobic digestion of steam explosion and organosolv pretreated corn stover2017In: Bioresource Technology, ISSN 0960-8524, E-ISSN 1873-2976, Vol. 244:1, p. 1129-1136Article in journal (Refereed)
    Abstract [en]

    The present work investigates the suitability of pretreated corn stover (CS) to serve as feedstock for high gravity (HG) ethanol production at solids-content of 24 wt%. Steam explosion, with and without the addition of H2SO4, and organosolv pretreated CS samples underwent a liquefaction/saccharification step followed by simultaneous saccharification and fermentation (SSF). Maximum ethanol concentration of ca. 76 g/L (78.3% ethanol yield) was obtained from steam exploded CS (SECS) with 0.2% H2SO4. Organosolv pretreated CS (OCS) also resulted in high ethanol concentration of ca. 65 g/L (62.3% ethanol yield). Moreover, methane production through anaerobic digestion (AD) was conducted from fermentation residues and resulted in maximum methane yields of ca. 120 and 69 mL/g volatile solids (VS) for SECS and OCS samples, respectively. The results indicated that the implementation of a liquefaction/saccharification step before SSF employing a liquefaction reactor seemed to handle HG conditions adequately.

  • 15.
    Kirtania, Kawnish
    et al.
    Monash University, Melbourne, VIC.
    Bhattacharya, Sankar
    Monash University, Melbourne, VIC.
    Application of the distributed activation energy model to the kinetic study of pyrolysis of the fresh water algae Chlorococcum humicola2012In: Bioresource Technology, ISSN 0960-8524, E-ISSN 1873-2976, Vol. 107, p. 476-481Article in journal (Refereed)
    Abstract [en]

    Apart from capturing carbon dioxide, fresh water algae can be used to produce biofuel. To assess the energy potential of Chlorococcum humicola, the alga's pyrolytic behavior was studied at heating rates of 5-20K/min in a thermobalance. To model the weight loss characteristics, an algorithm was developed based on the distributed activation energy model and applied to experimental data to extract the kinetics of the decomposition process. When the kinetic parameters estimated by this method were applied to another set of experimental data which were not used to estimate the parameters, the model was capable of predicting the pyrolysis behavior, in the new set of data with a R 2 value of 0.999479. The slow weight loss, that took place at the end of the pyrolysis process, was also accounted for by the proposed algorithm which is capable of predicting the pyrolysis kinetics of C. humicola at different heating rates. © 2011.

  • 16.
    Kirtania, Kawnish
    et al.
    Monash University, Melbourne, VIC.
    Tanner, Joanne
    Department of Chemical Engineering, Monash University.
    Kabir, Kazi Bayzid
    Department of Chemical Engineering, Monash University.
    Rajendran, Sharmen
    Department of Chemical Engineering, Monash University.
    Bhattacharya, Sankar
    Department of Chemical Engineering, Monash University.
    In situ synchrotron IR study relating temperature and heating rate to surface functional group changes in biomass2014In: Bioresource Technology, ISSN 0960-8524, E-ISSN 1873-2976, Vol. 151, p. 36-42Article in journal (Refereed)
    Abstract [en]

    Three types of woody biomass were investigated under pyrolysis condition to observe the change in the surface functional groups by Fourier transform infrared (FTIR) technique with increasing temperature under two different (5 and 150. °C/min) heating rates. The experiments were carried out in situ in the infrared microscopy beamline (IRM) of the Australian Synchrotron. The capability of the beamline made it possible to focus on single particles to obtain low noise measurements without mixing with KBr. At lower heating rate, the surface functional groups were completely removed by 550. °C. In case of higher heating rate, a delay was observed in losing the functional groups. Even at a high temperature, significant number of functional groups was retained after the higher heating rate experiments. This implies that at considerably high heating rates typical of industrial reactors, more functional groups will remain on the surface. © 2013 Elsevier Ltd.

  • 17.
    Kudahettige-Nilsson, Rasika
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Chemical Engineering.
    Helmerius, Jonas
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Chemical Engineering.
    Nilsson, Robert
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Chemical Engineering.
    Sjöblom, Magnus
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Chemical Engineering.
    Hodge, David
    Rova, Ulrika
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Chemical Engineering.
    Biobutanol Production by Clostridium acetobutylicum Using Xylose Recovered from Birch Kraft Black Liquor2015In: Bioresource Technology, ISSN 0960-8524, E-ISSN 1873-2976, Vol. 176, p. 71-79Article in journal (Refereed)
    Abstract [en]

    Acetone-Butanol-Ethanol (ABE) fermentation was studied using acid-hydrolyzed xylan recovered from hardwood Kraft black liquor by CO2 acidification as the only carbon source. Detoxification of hydrolyzate using activated carbon was conducted to evaluate the impact of inhibitor removal and fermentation. Xylose hydrolysis yields as high as 18.4% were demonstrated at the highest severity hydrolysis condition. Detoxification using active carbon was effective for removal of both phenolics (76-81%) and HMF (38-52%). Batch fermentation of the hydrolyzate and semi-defined P2 media resulted in a total solvent yield of 0.12-0.13 g/g and 0.34 g/g, corresponding to a butanol concentration of 1.8-2.1 g/L and 7.3 g/L respectively. This work is the first study of a process for the production of a biologically-derived biofuel from hemicelluloses solubilized during Kraft pulping and demonstrates the feasibility of utilizing xylan recovered directly from industrial Kraft pulping liquors as a feedstock for biological production of biofuels such as butanol.

  • 18.
    Liu, Yaoqian
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science. State Key Laboratory of Material-Oriented Chemical Engineering, Nanjing Tech University, Nanjing, China.
    Chen, Jingjing
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science. State Key Laboratory of Material-Oriented Chemical Engineering, Nanjing Tech University, Nanjing, China.
    Song, Jian
    State Key Laboratory of Material-Oriented Chemical Engineering, Nanjing Tech University, Nanjing, China.
    Hai, Zhong
    State Key Laboratory of Material-Oriented Chemical Engineering, Nanjing Tech University, Nanjing, China.
    Lu, Xiaohua
    State Key Laboratory of Material-Oriented Chemical Engineering, Nanjing Tech University, Nanjing, China.
    Ji, Xiaoyan
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science.
    Wang, Changsong
    State Key Laboratory of Material-Oriented Chemical Engineering, Nanjing Tech University, Nanjing, China.
    Adjusting the rheological properties of corn-straw slurry to reduce the agitation power consumption in anaerobic digestion2018In: Bioresource Technology, ISSN 0960-8524, E-ISSN 1873-2976, Vol. 272, p. 360-369Article in journal (Refereed)
    Abstract [en]

    Agitation power consumption (P) in the anaerobic digestion of biogas plants is a major consumer of electric energy. To reduce P by adjusting the rheological properties, in this work, the rheological properties of the corn-straw slurry were studied systematically considering the effects of TS, temperature and particle-size, and P was calculated based on the rheological behavior of the corn-straw slurry. The investigation shows that the corn-straw slurry is a non-Newtonian fluid and exhibit shear-thinning behavior, and the rheological properties can be well described with the power law model. The size-reduction is more effective compared to the option of temperature-increase to improve the agitation power efficiency, and the value of P can be reduced by up to 48.11 %. Since the size-reduction can also increase the methane yield, the reduction of the particle-size is a promising option to save P, especially at relatively high TSs and for the thermophilic AD process.

  • 19.
    Lundgren, Joakim
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science.
    Pettersson, Esbjörn
    Combustion of horse manure for heat production2009In: Bioresource Technology, ISSN 0960-8524, E-ISSN 1873-2976, Vol. 100, no 12, p. 3121-3126Article in journal (Refereed)
    Abstract [en]

    The main objectives of this paper have been to evaluate the use of horse manure and wood-shavings as a fuel for heat production and to provide sets of data on the chemical composition, ash characteristics and ash forming elements of the fuel. Another objective has been to investigate the possibility to use the ash as fertiliser by analysing the heavy metal and nutrient contents. The results showed that the fuel is well suited for combustion for heat production causing low emissions of products of incomplete combustion. The emissions of NOx were however high due to the high content of fuel bound nitrogen. Emissions of CO and NOx were typically in the range of 30-150 mg/Nm3 and 280-350 mg/Nm3 at 10 vol% O2, respectively. The analysis of the ash showed on sufficiently low concentration of heavy metals to allow recycling.

  • 20.
    Mamma, Diomi
    et al.
    National Technical University of Athens.
    Kourtoglou, Elisavet
    National Technical University of Athens.
    Christakopoulos, Paul
    Fungal multienzyme production on industrial by-products of the citrus-processing industry2008In: Bioresource Technology, ISSN 0960-8524, E-ISSN 1873-2976, Vol. 99, no 7, p. 2373-2383Article in journal (Refereed)
    Abstract [en]

    Orange peels is the principal solid by-product of the citrus processing industry and the disposal of the fresh peels is becoming a major problem to many factories. Dry citrus peels are rich in pectin, cellulose and hemicellulose and may be used as a fermentation substrate. Production of multienzyme preparations containing pectinolytic, cellulolytic and xylanolytic enzymes by the mesophilic fungi Aspergillus niger BTL, Fusarium oxysporum F3, Neurospora crassa DSM 1129 and Penicillium decumbens under solid-state fermentation (SSF) on dry orange peels was enhanced by optimization of initial pH of the culture medium and initial moisture level. Under optimal conditions A. niger BTL was by far the most potent strain in polygalacturonase and pectate lyase, production followed by F. oxysporum F3, N. crassa DSM 1129 and P. decumbens. N. crassa DSM 1129 produced the highest endoglucanase activity and P. decumbens the lowest one. Comparison of xylanase production revealed that A. niger BTL produced the highest activity followed by N. crassa DSM 1129, P. decumbens and F. oxysporum F3. N. crassa DSM 1129 and P. decumbens did not produce any β-xylosidase activity, while A. niger BTL produced approximately 10 times more β-xylosidase than F. oxysporum F3. The highest invertase activity was produced by A. niger BTL while the lowest ones by F. oxysporum F3 and P. decumbens. After SSF of the four fungi, under optimal conditions, the fermented substrate was either directly exposed to autohydrolysis or new material was added, and the in situ produced multienzyme systems were successfully used for the partial degradation of orange peels polysaccharides and the liberation of fermentable sugars.

  • 21.
    Matsakas, Leonidas
    et al.
    National Technical University of Athens.
    Christakopoulos, Paul
    National Technical University of Athens.
    Fermentation of liquefacted hydrothermally pretreated sweet sorghum bagasse to ethanol at high-solids content2013In: Bioresource Technology, ISSN 0960-8524, E-ISSN 1873-2976, Vol. 127, p. 202-208Article in journal (Refereed)
    Abstract [en]

    The ability of sweet sorghum bagasse to be utilized as feedstock for ethanol production at high initial dry matter concentration was investigated. In order to achieve high enzymatic hydrolysis yield, a hydrothermal pretreatment prior to liquefaction and saccharification was applied. Response surface methodology had been employed in order to optimize the pretreatment step, taking into account the yield of cellulose hydrolysis. Liquefaction of the pretreated bagasse was performed at a specially designed liquefaction chamber at 50 °C for either 12 or 24 h using an enzyme loading of 10 FPU/g·DM and 18% DM. Fermentation of liquefacted bagasse was not affected by liquefaction duration and leaded to an ethanol production of 41.43 g/L and a volumetric productivity of 1.88 g/L h. The addition of extra enzymes at the start up of SSF enhanced both ethanol concentration and volumetric productivity by 16% and 17% after 12 and 24 h saccharification, respectively.

  • 22.
    Matsakas, Leonidas
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Chemical Engineering.
    Novak, Katharina
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Chemical Engineering.
    Enman, Josefine
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Chemical Engineering.
    Christakopoulos, Paul
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Chemical Engineering.
    Rova, Ulrika
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Chemical Engineering.
    Acetate-detoxification of wood hydrolysates with alkali tolerant Bacillus sp. as a strategy to enhance the lipid production from Rhodosporidium toruloides2017In: Bioresource Technology, ISSN 0960-8524, E-ISSN 1873-2976, Vol. 242, p. 287-294Article in journal (Refereed)
    Abstract [en]

    The aim of the current work was to convert an acetate-rich hemicellulose liquid fraction (LF) from hot-water extraction of Betula pendula to oils for biodiesel, with Rhodosporidium toruloides. The toxicity of acetate was circumvented by biological detoxification with an isolated alkali-tolerant and acetate-resistant Bacillus sp. strain. Removal of other lignocellulose-derived inhibitors, such as furfural and phenols, was evaluated by two strategies; an activated carbon (AC) treatment of the undiluted LF, and dilution of the LF by 25% (0.75LF) and 50%. (0.50LF). The bacterium consumed most of the acetic acid in 6-8 days in the treated or diluted media, which were subsequently used for cultivation of the yeast, for conversion of sugars to oils. The oil concentration reached 2.8 and 1.8 g/L, in the AC LF and 0.75LF medium, respectively. In comparison, the oil accumulation in the same media without prior cultivation of Bacillus sp. was 0.86 and 0.03 g/L, respectively.

  • 23.
    Matsakas, Leonidas
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Chemical Engineering.
    Raghavendran, Vijayendran
    Chalmers University of Technology, Division of Industrial Biotechnology, Department of Biology and Biological Engineering,Göteborg, Sweden. Department of Molecular Biology and Biotechnology, Firth Court, Western Bank, University of Sheffield, UK.
    Yakimenko, Olga
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Chemical Engineering.
    Persson, Gustav
    Chalmers University of Technology, Department of Physics, Göteborg, Sweden.
    Olsson, Eva
    Chalmers University of Technology, Department of Physics, Göteborg, Sweden.
    Rova, Ulrika
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Chemical Engineering.
    Olsson, Lisbeth
    Chalmers University of Technology, Division of Industrial Biotechnology, Department of Biology and Biological Engineering, Göteborg, Sweden.
    Christakopoulos, Paul
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Chemical Engineering.
    Lignin-first biomass fractionation using a hybrid organosolv: Steam explosion pretreatment technology improves the saccharification and fermentability of spruce biomass2019In: Bioresource Technology, ISSN 0960-8524, E-ISSN 1873-2976, Vol. 273, p. 521-528Article in journal (Refereed)
    Abstract [en]

    For a transition to a sustainable society, fuels, chemicals, and materials should be produced from renewable resources. Lignocellulosic biomass constitutes an abundant and renewable feedstock; however, its successful application in a biorefinery requires efficient fractionation into its components; cellulose, hemicellulose and lignin. Here, we demonstrate that a newly established hybrid organosolv – steam explosion pretreatment can effectively fractionate spruce biomass to yield pretreated solids with high cellulose (72% w/w) and low lignin (delignification up to 79.4% w/w) content. The cellulose-rich pretreated solids present high saccharification yields (up to 61% w/w) making them ideal for subsequent bioconversion processes. Moreover, under high-gravity conditions (22% w/w) we obtained an ethanol titer of 61.7 g/L, the highest so far reported for spruce biomass. Finally, the obtained high-purity lignin is suitable for various advanced applications. In conclusion, hybrid organosolv pretreatment could offer a closed-loop biorefinery while simultaneously adding value to all biomass components.

  • 24.
    Mesfun, Sennai
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science.
    Lundgren, Joakim
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science.
    Grip, Carl-Erik
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science.
    Toffolo, Andrea
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science.
    Kudahettige-Nilsson, Rasika
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Chemical Engineering.
    Rova, Ulrika
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Chemical Engineering.
    Black liquor fractionation for biofuels production: A techno-economic assessment2014In: Bioresource Technology, ISSN 0960-8524, E-ISSN 1873-2976, Vol. 166, p. 508-517Article in journal (Refereed)
    Abstract [en]

    The hemicelluloses fraction of black liquor is an underutilized resource in many chemical pulp mills. It is possible to extract and separate the lignin and hemicelluloses from the black liquor and use the hemicelluloses for biochemical conversion into biofuels and chemicals. Precipitation of the lignin from the black liquor would consequently decrease the thermal load on the recovery boiler, which is often referred to as a bottleneck for increased pulp production. The objective of this work is to techno-economically evaluate the production of sodium-free lignin as a solid fuel and butanol to be used as fossil gasoline replacement by fractionating black liquor. The hydrolysis and fermentation processes are modeled in Aspen Plus to analyze energy and material balances as well as to evaluate the plant economics. A mathematical model of an existing pulp and paper mill is used to analyze the effects on the energy performance of the mill subprocesses.

  • 25.
    Nilsson, Robert
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Chemical Engineering.
    Bauer, Fredric
    Chemical Engineering, Lund University.
    Mesfun, Sennai
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science.
    Hulteberg, Christian
    Chemical Engineering, Lund University.
    Lundgren, Joakim
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science.
    Wännström, Sune
    SP Technical Research Institute of Sweden.
    Rova, Ulrika
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Chemical Engineering.
    Berglund, Kris
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Chemical Engineering.
    Techno-economics of carbon preserving butanol production using a combined fermentative and catalytic approach2014In: Bioresource Technology, ISSN 0960-8524, E-ISSN 1873-2976, Vol. 161, p. 263-269Article in journal (Refereed)
    Abstract [en]

    This paper presents a novel process for n-butanol production which combines a fermentation consuming carbon dioxide (succinic acid fermentation) with subsequent catalytic reduction steps to add hydrogen to form butanol. Process simulations in Aspen Plus have been the basis for the techno-economic analyses performed. The overall economy for the novel process cannot be justified, as production of succinic acid by fermentation is too costly. Though, succinic acid price is expected to drop drastically in a near future. By fully integrating the succinic acid fermentation with the catalytic conversion the need for costly recovery operations could be reduced. The hybrid process would need 22% less raw material than the butanol fermentation at a succinic acid fermentation yield of 0.7 g/g substrate. Additionally, a carbon dioxide fixation of up to 13 ktonnes could be achieved at a plant with an annual butanol production of 10 ktonnes

  • 26.
    Panagiotou, Gianni
    et al.
    National Technical University of Athens.
    Pachidou, Fotini
    National Technical University of Athens.
    Petroutsos, Dimitris
    National Technical University of Athens.
    Olsson, Lisbeth
    Technical University of Denmark.
    Christakopoulos, Paul
    Fermentation characteristics of Fusarium oxysporum grown on acetate2008In: Bioresource Technology, ISSN 0960-8524, E-ISSN 1873-2976, Vol. 99, no 15, p. 7397-7401Article in journal (Refereed)
    Abstract [en]

    In this study, the growth characteristics of Fusariumoxysporum were evaluated in minimal medium using acetate or different mixtures of acetate and glucose as carbon source. The minimum inhibitory concentration (MIC) of acetic acid that F.oxysporum cells could tolerate was 0.8% w/v while glucose was consumed preferentially to acetate. The activity of isocitrate lyase was high when cells were grown on acetate and acetate plus glucose indicating an activation of the glyoxylate cycle. Investigation of the metabolic fingerprinting and footprinting revealed higher levels of intracellular and extracellular TCA cycle intermediates when F.oxysporum cells were grown on mixtures of acetate and glucose compared to growth on only glucose. Our data support the hypothesis that a higher flux through TCA cycle during acetate consumption could significantly increase the pool of NADH, resulting in the activation of succinate–propionate pathway which consumes reducing power (NADH) via conversion of succinate to propionyl-CoA and produce propionate.

  • 27.
    Patel, Alok
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Chemical Engineering.
    Hruzova, Katerina
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Chemical Engineering.
    Rova, Ulrika
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Chemical Engineering.
    Christakopoulos, Paul
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Chemical Engineering.
    Matsakas, Leonidas
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Chemical Engineering.
    Sustainable biorefinery concept for biofuel production through holistic volarization of food waste2019In: Bioresource Technology, ISSN 0960-8524, E-ISSN 1873-2976, Vol. 294, article id 122247Article in journal (Refereed)
    Abstract [en]

    The aim of this study was to utilize the whole food waste in two stages. In the first stage, the carbohydrate and protein fractions of food waste recovered after enzymatic hydrolysis was used to cultivate heterotrophic microalgae, resulting in biomass yield of 0.346 ± 0.09 g/gsugars and lipid yield of 0.216 ± 0.06 g/gsugars. In the second stage, oil (14.15% w/w) was extracted from food waste after hydrolysis and converted to biodiesel by a two-step transesterification reaction that generated 135.8 g/kgfood waste of fatty acid methyl esters and 13.8 g/kgfood waste of crude glycerol. Finally, crude glycerol obtained from both processes was used at 20 g/L to cultivate heterotrophic microalgae, resulting in a cell dry weight and total lipid concentration of 6.23 g/L and 2.91 g/L, respectively. A total 248.21 g of fatty acid methyl esters were obtained from the 1 kg of food waste through this integrated process.

  • 28.
    Patel, Alok
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Chemical Engineering.
    Matsakas, Leonidas
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Chemical Engineering.
    Rova, Ulrika
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Chemical Engineering.
    Christakopoulos, Paul
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Chemical Engineering.
    A perspective on biotechnological applications of thermophilic microalgae and cyanobacteria2019In: Bioresource Technology, ISSN 0960-8524, E-ISSN 1873-2976, Vol. 278, p. 424-434Article in journal (Refereed)
    Abstract [en]

    The importance of expanding our knowledge on microorganisms derived from extreme environments stems from the development of novel and sustainable technologies for our health, food, and environment. Microalgae and cyanobacteria represent a group of diverse microorganisms that inhabit a wide range of environments, are capable of oxygenic photosynthesis, and form a thick microbial mat even at extreme environments. Studies of thermophilic microorganisms have shown a considerable biotechnological potential due to their optimum growth and metabolisms at high temperatures (≥50 °C), which is supported by their thermostable enzymes. Microalgal and cyanobacterial communities present in high-temperature ecosystems account for a large part of the total ecosystem biomass and productivity, and can be exploited to generate several value-added products of agricultural, pharmaceutical, nutraceutical, and industrial relevance. This review provides an overview on the current status of biotechnological applications of thermophilic microalgae and cyanobacteria, with an outlook on the challenges and future prospects.

  • 29.
    Pradhan, Nilotpala
    et al.
    Regional Research Laboratory, CSIR, Bhubaneshwar 751 013, India.
    Das, B.
    Regional Research Laboratory, CSIR, Bhubaneshwar 751 013, India.
    Gahan, Chandra Sekhar
    Kar, Rabi Narayana
    Regional Research Laboratory, CSIR, Bhubaneshwar 751 013, India.
    Sukla, Lala Bihari
    Regional Research Laboratory, CSIR, Bhubaneshwar 751 013, India.
    Beneficiation of iron ore slime using Aspergillus niger and Bacillus circulans2006In: Bioresource Technology, ISSN 0960-8524, E-ISSN 1873-2976, Vol. 97, no 15, p. 1876-1879Article in journal (Refereed)
    Abstract [en]

    Studies were carried out on the removal of alumina from iron ore slime containing (%) Fe2O3 75.7, Al2O3 9.95, SiO2 6.1, Fe (total) 52.94 with the help of Bacillus circulans and Aspergillus niger. B. circulans and A. niger showed 39% and 38% alumina removal after six and 15 days of in situ leaching at 10% pulp density, respectively. Culture filtrate leaching with A. niger removed 20% alumina at 2% pulp density with 13 day old culture filtrate. B. circulans was more efficient than A. niger for selective removal of alumina. In case of A. niger in situ leaching rather than culture filtrate leaching was found to be more effective

  • 30.
    Scott, Felipe
    et al.
    School of Biochemical Engineering, Pontificia Universidad Católica de Valparaíso.
    Li, Muyang
    DOE-Great Lakes Bioenergy Research Center, Michigan State University, East Lansing.
    Williams, Daniel L.
    DOE-Great Lakes Bioenergy Research Center, Michigan State University, East Lansing.
    Conejeros, Raúl
    School of Biochemical Engineering, Pontificia Universidad Católica de Valparaíso.
    Hodge, David
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Sustainable Process Engineering.
    Aroca, German
    School of Biochemical Engineering, Pontificia Universidad Católica de Valparaíso.
    Corn stover semi-mechanistic enzymatic hydrolysis model with tight parameter confidence intervals for model-based process design and optimization2015In: Bioresource Technology, ISSN 0960-8524, E-ISSN 1873-2976, Vol. 177, p. 255-265Article in journal (Refereed)
    Abstract [en]

    Uncertainty associated to the estimated values of the parameters in a model is a key piece of information for decision makers and model users. However, this information is typically not reported or the confidence intervals are too large to be useful. A semi-mechanistic model for the enzymatic saccharification of dilute acid pretreated corn stover is proposed in this work, the model is a modification of an existing one providing a statistically significant improved fit towards a set of experimental data that includes varying initial solid loadings (10 to 25 % w/w) and the use of the pretreatment liquor and washed solids with or without supplementation of key inhibitors. A subset of 8 out of 17 parameters was identified, showing sufficiently tight confidence intervals to be used in uncertainty propagation and model analysis, without requiring interval truncation via expert judgment.

  • 31.
    Stoklosa, Ryan J.
    et al.
    Department of Chemical Engineering and Materials Science, Michigan State University, East Lansing.
    del Pilar Orjuela, Andrea
    Department of Chemical Engineering and Materials Science, Michigan State University, East Lansing.
    da Costa Sousa, Leonardo
    Department of Chemical Engineering and Materials Science, Michigan State University, East Lansing.
    Uppugundla, Nirmal
    Department of Chemical Engineering and Materials Science, Michigan State University, East Lansing.
    Williams, Daniel L.
    Department of Chemical Engineering and Materials Science, Michigan State University, East Lansing.
    Dale, Bruce E.
    Department of Chemical Engineering and Materials Science, Michigan State University, East Lansing.
    Hodge, David
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Chemical Engineering.
    Balan, Venkatesh
    Department of Chemical Engineering and Materials Science, Michigan State University, East Lansing.
    Techno-economic comparison of centralized versus decentralized biorefineries for two alkaline pretreatment processes2017In: Bioresource Technology, ISSN 0960-8524, E-ISSN 1873-2976, Vol. 226, p. 9-17Article in journal (Refereed)
    Abstract [en]

    In this work, corn stover subjected to ammonia fiber expansion (AFEX™) pretreatment or alkaline pre-extraction followed by hydrogen peroxide post-treatment (AHP pretreatment) were compared for their enzymatic hydrolysis yields over a range of solids loadings, enzymes loadings, and enzyme combinations. Process techno-economic models were compared for cellulosic ethanol production for a biorefinery that handles 2000 tons per day of corn stover employing a centralized biorefinery approach with AHP or a de-centralized AFEX pretreatment followed by biomass densification feeding a centralized biorefinery. A techno-economic analysis (TEA) of these scenarios shows that the AFEX process resulted in the highest capital investment but also has the lowest minimum ethanol selling price (MESP) at $2.09/gal, primarily due to good energy integration and an efficient ammonia recovery system. The economics of AHP could be made more competitive if oxidant loadings were reduced and the alkali and sugar losses were also decreased.

  • 32. Umeki, Kentaro
    et al.
    Roh, Seon-ah
    Min, Tai-jin
    Namioka, Tomoaki
    Yoshikawa, Kunio
    A simple expression for the apparent reaction rate of large wood char gasification with steam2010In: Bioresource Technology, ISSN 0960-8524, E-ISSN 1873-2976, Vol. 101, no 11, p. 4187-4192Article in journal (Refereed)
  • 33.
    Williams, Daniel L.
    et al.
    Department of Chemical Engineering and Materials Science, Michigan State University, East Lansing.
    Crowe, Jacob D.
    Department of Chemical Engineering and Materials Science, Michigan State University, East Lansing.
    Ong, Rebecca G.
    Department of Chemical Engineering, Michigan Technological University, Houghton, MI.
    Hodge, David
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Chemical Engineering.
    Water Sorption in Pretreated Grasses as a Predictor of Enzymatic Hydrolysis Yields2017In: Bioresource Technology, ISSN 0960-8524, E-ISSN 1873-2976, Vol. 245, p. 242-249Article in journal (Refereed)
    Abstract [en]

    This work investigated the impact of two alkaline pretreatments, ammonia fiber expansion (AFEX) and alkaline hydrogen peroxide (AHP) delignification performed over a range of conditions on the properties of corn stover and switchgrass. Changes in feedstock properties resulting from pretreatment were subsequently compared to enzymatic hydrolysis yields to examine the relationship between enzymatic hydrolysis and cell wall properties. The pretreatments function to increase enzymatic hydrolysis yields through different mechanisms; AFEX pretreatment through lignin relocalization and some xylan solubilization and AHP primarily through lignin solubilization. An important outcome was that while changes in lignin content in AHP-delignified biomass could be clearly correlated to improved response to hydrolysis, compositional changes alone in AFEX-pretreated biomass could not explain differences in hydrolysis yields. We determined the water retention value, which characterizes the association of water with the cell wall of the pretreated biomass, can be used to predict hydrolysis yields for all pretreated biomass.

  • 34.
    Xiong, S.
    et al.
    Swedish University of Agricultural Sciences, Department of Forest Biomaterial and Technology, Umeå, Sweden.
    Martín, C.
    Umeå University, Department of Chemistry, Umeå, Sweden.
    Eilertsen, L.
    Swedish University of Agricultural Sciences, Department of Forest Biomaterial and Technology, Umeå, Sweden. Swedish University of Agricultural Sciences, Department of Forest Genetics and Plant Physiology, Umeå Plant Science Center, Umeå, Sweden.
    Wei, M.
    Swedish University of Agricultural Sciences, Department of Forest Biomaterial and Technology, Umeå, Sweden. Guangxi University, College of Agronomy, Nanning, China.
    Myronycheva, Olena
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering. Swedish University of Agricultural Sciences, Department of Forest Biomaterial and Technology, Umeå, Sweden.
    Larsson, S.H.
    Swedish University of Agricultural Sciences, Department of Forest Biomaterial and Technology, Umeå, Sweden.
    Lestander, T.A.
    Swedish University of Agricultural Sciences, Department of Forest Biomaterial and Technology, Umeå, Sweden.
    Atterhem, L.
    Biosteam AB, Burträsk, Sweden.
    Jönsson, L.J.
    Umeå University, Department of Chemistry, Umeå, Sweden.
    Energy-efficient substrate pasteurisation for combined production of shiitake mushroom (Lentinula edodes) and bioethanol2019In: Bioresource Technology, ISSN 0960-8524, E-ISSN 1873-2976, Vol. 274, p. 65-72Article in journal (Refereed)
    Abstract [en]

    Hot-air (75 -100°C) pasteurisation (HAP) of birch-wood-based substrate was compared to conventional autoclaving (steam at 121 °C) with regard to shiitake growth and yield, chemical composition of heat-pretreated material and spent mushroom substrate (SMS), enzymatic digestibility of glucan in SMS, and theoretical bioethanol yield. Compared to autoclaving, HAP resulted in faster mycelial growth, earlier fructification, and higher or comparable fruit-body yield. The heat pretreatment methods did not differ regarding the fractions of carbohydrate and lignin in pretreated material and SMS, but HAP typically resulted in lower fractions of extractives. Shiitake cultivation, which reduced the mass fraction of lignin to less than half of the initial without having any major impact on the mass fraction of glucan, enhanced enzymatic hydrolysis of glucan about four-fold. The choice of heating method did not affect enzymatic digestibility. Thus, HAP could substitute autoclaving and facilitate combined shiitake mushroom and bioethanol production.

  • 35.
    Xiros, C.
    et al.
    National Technical University of Athens.
    Karapodis, P.
    National Technical University of Athens.
    Christakopoulos, Paul
    Factors affecting cellulose and hemicellulose hydrolysis of alkali treated brewers spent grain by Fusarium oxysporum enzyme extract2011In: Bioresource Technology, ISSN 0960-8524, E-ISSN 1873-2976, Vol. 102, no 2, p. 1688-1696Article in journal (Refereed)
    Abstract [en]

    The enzymatic degradation of polysaccharides to monosaccharides is an essential step in bioconversion processes of lignocellulosic materials. Alkali treated brewers spent grain was used as a model substrate for the study of cellulose and hemicellulose hydrolysis by Fusarium oxysporum enzyme extract. The results obtained showed that cellulose and hemicellulose conversions are not affected by the same factors, implementing different strategies for a successful bioconversion. Satisfactory cellulose conversion could be achieved by increasing the enzyme dosage in order to overcome the end-product inhibition, while the complexity of hemicellulose structure imposes the presence of specific enzyme activities in the enzyme mixture used. All the factors investigated were combined in a mathematical model describing and predicting alkali treated brewers spent grain conversion by F. oxysporum enzyme extract

  • 36.
    Xiros, Charilaos
    et al.
    National Technical University of Athens.
    Katapodis, Petros
    National Technical University of Athens.
    Christakopoulos, Paul
    Evaluation of Fusarium oxysporum cellulolytic system for an efficient hydrolysis of hydrothermally treated wheat straw2009In: Bioresource Technology, ISSN 0960-8524, E-ISSN 1873-2976, Vol. 100, no 21, p. 5362-5365Article in journal (Refereed)
    Abstract [en]

    The crude multienzyme extract produced by Fusarium oxysporum cultivated under submerged conditions in 20 L bioreactor using brewers spent grain and corn cobs in a ratio 2:1 as the carbon source was evaluated with regard to an efficient saccharification of hydrothermally treated wheat straw. Several factors concerning the obtained hydrolysis yield and reaction rate were investigated. The takeout of product sugars (in situ) was effective at reducing end-product inhibition and lead to a bioconversion about 80% of the theoretical. A kinetic model incorporating dynamic adsorption, enzymatic hydrolysis, and product inhibition was developed. The model predicted very satisfactorily the experimental data.

  • 37.
    Xiros, Charilaos
    et al.
    National Technical University of Athens.
    Moukouli, Maria
    National Technical University of Athens.
    Topakas, Evangelos
    National Technical University of Athens.
    Christakopoulos, Paul
    Factors affecting ferulic acid release from brewer's spent grain by Fusarium oxysporum enzymatic system2009In: Bioresource Technology, ISSN 0960-8524, E-ISSN 1873-2976, Vol. 100, no 23, p. 5917-5921Article in journal (Refereed)
    Abstract [en]

    In this study, the factors affecting ferulic acid (FA) release from Brewer’s spent grain (BSG), by the crude enzyme extract of Fusarium oxysporum were investigated. In order to evaluate the importance of the multienzyme preparation on FA release, the synergistic action of feruloyl esterase (FAE, FoFaeC-12213) and xylanase (Trichoderma longibrachiatum M3) monoenzymes was studied. More than double amount of FA release (1 mg g−1 dry BSG) was observed during hydrolytic reactions by the crude enzyme extract compared to hydrolysis by the monoenzymes (0.37 mg g−1 dry BSG). The protease content of the crude extract and the inhibitory effect of FA as an end-product were also evaluated concerning their effect on FA release. The protease treatment prior to hydrolysis by monoenzymes enhanced FA release about 100%, while, for the first time in literature, FA in solution found to have a significant inhibitory effect on FAE activity and on total FA release.

  • 38.
    Xiros, Charilaos
    et al.
    National Technical University of Athens.
    Topakas, Evanglos
    National Technical University of Athens.
    Katapodis, Petros
    National Technical University of Athens.
    Christakopoulos, Paul
    Hydrolysis and fermentation of brewer’s spent grain from Neurospora crassa2008In: Bioresource Technology, ISSN 0960-8524, E-ISSN 1873-2976, Vol. 99, no 13, p. 5427-5435Article in journal (Refereed)
    Abstract [en]

    In this study, the ethanol production by the mesophilic fungus Neurospora crassa from BG was studied and optimized concerning the induction of lignocellulose degrading enzymes and the production phase as well. The production of cellulolytic and hemicellulolytic enzymes was studied under solid-state cultivation (SSC). SSC in a laboratory horizontal bioreactor using the optimized medium, WS and BG in the ratio 1:1 and initial moisture level 61.5%, allowed the large scale production of the multienzymatic system. Similar yields with those from flasks experiments, as high as 1073, 56, 4.2, 1.6, 3.1, 5.7 and 0.52 U g−1 carbon source of xylanase, endoglucanase, cellobiohydrolase, β-glucosidase, α-l-arabinofuranosidase, acetyl esterase and feruloyl esterase, respectively, were obtained. Chromogenic (fluorogenic) 4-methylumbelliferyl substrates were used to characterize the major activities of the multienzyme component, after the separation by isoelectric focusing (IEF) electrophoresis. Alkali pre-treated BG was used for ethanol production. A yield of about 74 g of ethanol kg−1 dry BG (5, 6 g L−1) was obtained under optimum conditions (aeration 0.1 vvm, pre-treatment with 1 g NaOH 10 g−1 dry BG).

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