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  • 1
    Electronic Resource
    Electronic Resource
    Phase Holdup and Dispersion in a Three-Phase Fluidized-Bed Bioreactor with Low-Density Gel Beads (1990)
    Oxford, UK : Blackwell Publishing Ltd
    Annals of the New York Academy of Sciences 589 (1990), S. 0 
    Details
    ISSN: 1749-6632
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Natural Sciences in General
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1749-6632.1990.tb24279.x
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  • 2
    Electronic Resource
    Electronic Resource
    A proposed biparticle fluidized-bed for lactic acid fermentation and simultaneous adsorption (1992)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 39 (1992), S. 365-368 
    Details
    ISSN: 0006-3592
    Keywords: fermentation ; adsorption ; lactic acid ; fluidized bed ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A bioreactor configuration is proposed for simultaneous fermentation and separation of the desired product. The bioreactor consists of a columnar fluidized bed of immobilized microorganisms. Denser adsorbent particles are added to this column. These adsorbent particles fall through the bed, absorb the product, and are removed from the base of the columnar reactor. The system hydrodynamics and the separability of the two types of particles were confirmed for low-density gel beads. The addition of the adsorbent, activated carbon, to a fermentation of Lactobacillus delbreuckii absorbed lactic acid. The addition of adsorbent enhanced the fermentation and controlled the pH.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bit.260390317
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  • 3
    Electronic Resource
    Electronic Resource
    Development of a predictive description of an immobilized-cell, three-phase, fluidized-bed bioreactor (1995)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 46 (1995), S. 139-146 
    Details
    ISSN: 0006-3592
    Keywords: fluidized-bed bioreactor ; concentration profile ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A fully predictive mathematical description of a three-phase, tapered, fluidized-bed bioreactor is developed. This mathematical model includes the effects of the tapered bed, variable dispersion coefficient, and variable solid holdup upon the concentration profiles developed in the bed. In addition, the effect of the concentration profile which is developed inside the biocatalyst bead is included by means of an effectiveness factor calculation. Using accepted correlations for the dispersion coefficient and for the liquid, gas, and solid holdup in the bed, the model is fully predictive. The model was found to adequately predict experimental obtained concentration profiles. Then, the model was used to examine the various phase holdups through the bed and the degree to which the dispersion coefficient varied through the bed. The effect of changes in these calculated variables upon the reaction rate is discussed. © 1995 John Wiley & Sons, Inc.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bit.260460207
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  • 4
    Electronic Resource
    Electronic Resource
    Effect of pH oscillations on a competing mixed culture (1986)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 28 (1986), S. 1127-1137 
    Details
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Two microorganisms, E. coli and S. cerevisiae, competing for glucose were maintained in a stable cycle of coexistence by alternating the growth advantage between the two organisms by oscillating the pH in a Chemostat. Pure culture experiments found S. cerevisiae to be insensitive to pH between 5 and 4.3 with a maximum specific growth rate (μmax) of 0.4/hr; while μmax of E. coli decreased from 0.6 h-1 at pH 5 to 0.1 h-1 at pH 4.3. Steady-state and cross-inoculation chemostat runs at a dilution rate of 0.17 h-1 confirmed the expectation that the mixed culture system is unstable at constant pH with E. coli dominating at pH 5 and S. cerevisiae dominating at pH 4.3. Three pH oscillation experiments were performed at D =0.17 h-1 with 1 g per liter glucose feed. The 16 h/16 h cycle was stable for six periods with a stable alternating cycle of E. coli and S. cerevisiae being quickly established. A 18 h pH 5/14 h pH 4.3 cycle was found to be stable with smaller yeast concentrations. A 6 h/6 h cycle was found unstable with yeast washout. Simulation results were compared with these runs and were used to predict the onset of instability. Oscillations of pH can force stable persistence of a competing mixed culture that is otherwise unstable. Thus, varying conditions are experimentally demonstrated to be one explanation for competitive coexistence.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bit.260280802
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  • 5
    Electronic Resource
    Electronic Resource
    Coexistence of S. cerevisiae and E. coli in chemostat under substrate competition and product inhibition (1986)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 28 (1986), S. 1742-1752 
    Details
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A mixed culture of Saccharomyces cerevisiae and Escherichia coli was established in a stable coexistence steady state in a chemostat under constant operating conditions. The species competed for glucose, the growth-limiting resource, and produced acetate and ethanol. The acetic acid was shown to be very inhibitory to E. coli in pure culture at pH 5 while ethanol inhibition was only marginal. No significant inhibition of S. cerevisiae growth was observed by either acetate or ethanol. Pure culture parameters were measured and used in the analysis. Linearized stability analysis for the case when both organisms produce the inhibitor showed that a transition through three stable outcomes was possible as the feed concentration is lowered. Experimental studies verified these predictions, and successive transitions from a yeast growth steady state, to a coexistence steady state, and to an E. coli growth steady state were obtained by lowering the glucose concentration in the feed from 10 to 5 to 2.5 g/L, respectively. This dynamic behavior is distinct from the outcomes of other competition-inhibition combinations and experimentally demonstrates for the first time that coexistence is possible due to substrate competition and product inhibition.
    Additional Material: 13 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bit.260281119
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  • 6
    Electronic Resource
    Electronic Resource
    Size changes associated with metal adsorption onto modified bone gelatin beads (1991)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 38 (1991), S. 923-928 
    Details
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Significant quantities of heavy metals will adsorb onto modified bone gelatin beads. As this adsorption occurs, the bead can undergo a substantial volume change. Research has shown that the equilibrium bead diameter was a function of the solution pH and the ion concentration in the solution. Here, we demonstrate that under certain conditions, the volume of the beads that absorbed the metal was only 35% of the bead volume when no metal was adsorbed. By taking advantages of these size changes, a fluidized-bed separator can be operated such that natural segregation of loaded beads occurs. This phenomenon may facilitate the design of continous separators for the recovery and concentration of heavy-metal-contaminated waters. These concepts are demonstrated using Cu2+ adsorption onto such beads.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bit.260380813
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  • 7
    Electronic Resource
    Electronic Resource
    Minimizing the errors associated with the determination of effective diffusion coefficients when using spherical cell immobilization matrices (1991)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 37 (1991), S. 386-388 
    Details
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Gel materials are often used to entrap biological catalysts. Several experimental methods have been proposed to estimate the diffusion coefficient of important chemical species within these materials. An error analysis for the bead method was performed and, contrary to previously reported results, when proper experimental conditions were employed, the error associated with the bead method was similar to that obtained using the other common methods.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bit.260370414
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  • 8
    Electronic Resource
    Electronic Resource
    Minimizing the errors associated with the determination of effective diffusion coefficients when using spherical cell immobilization matrices (1991)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 38 (1991), S. 961-961 
    Details
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bit.260380820
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  • 9
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    Technoeconomic and life-cycle analysis of single-step catalytic conversion of wet ethanol into fungible fuel blendstocks (2019)
    National Academy of Sciences
    Details
    Publication Date: 2019-11-25
    Description: Technoeconomic and life-cycle analyses are presented for catalytic conversion of ethanol to fungible hydrocarbon fuel blendstocks, informed by advances in catalyst and process development. Whereas prior work toward this end focused on 3-step processes featuring dehydration, oligomerization, and hydrogenation, the consolidated alcohol dehydration and oligomerization (CADO) approach described here results in 1-step conversion of wet ethanol vapor (40 wt% in water) to hydrocarbons and water over a metal-modified zeolite catalyst. A development project increased liquid hydrocarbon yields from 36% of theoretical to 〉80%, reduced catalyst cost by an order of magnitude, scaled up the process by 300-fold, and reduced projected costs of ethanol conversion 12-fold. Current CADO products conform most closely to gasoline blendstocks, but can be blended with jet fuel at low levels today, and could potentially be blended at higher levels in the future. Operating plus annualized capital costs for conversion of wet ethanol to fungible blendstocks are estimated at $2.00/GJ for CADO today and $1.44/GJ in the future, similar to the unit energy cost of producing anhydrous ethanol from wet ethanol ($1.46/GJ). Including the cost of ethanol from either corn or future cellulosic biomass but not production incentives, projected minimum selling prices for fungible blendstocks produced via CADO are competitive with conventional jet fuel when oil is $100 per barrel but not at $60 per barrel. However, with existing production incentives, the projected minimum blendstock selling price is competitive with oil at $60 per barrel. Life-cycle greenhouse gas emission reductions for CADO-derived hydrocarbon blendstocks closely follow those for the ethanol feedstock.
    Print ISSN: 0027-8424
    Electronic ISSN: 1091-6490
    Topics: Biology , Medicine , Natural Sciences in General
    Published by National Academy of Sciences
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  • 10
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    Deconstruction of biomass enabled by local demixing of cosolvents at cellulose and lignin surfaces (2020)
    National Academy of Sciences
    Details
    Publication Date: 2020-07-07
    Description: A particularly promising approach to deconstructing and fractionating lignocellulosic biomass to produce green renewable fuels and high-value chemicals pretreats the biomass with organic solvents in aqueous solution. Here, neutron scattering and molecular-dynamics simulations reveal the temperature-dependent morphological changes in poplar wood biomass during tetrahydrofuran (THF):water pretreatment and provide a mechanism by which the solvent components drive efficient biomass breakdown. Whereas lignin dissociates over a wide temperature range (〉25 °C) cellulose disruption occurs only above 150 °C. Neutron scattering with contrast variation provides direct evidence for the formation of THF-rich nanoclusters (Rg∼ 0.5 nm) on the nonpolar cellulose surfaces and on hydrophobic lignin, and equivalent water-rich nanoclusters on polar cellulose surfaces. The disassembly of the amphiphilic biomass is thus enabled through the local demixing of highly functional cosolvents, THF and water, which preferentially solvate specific biomass surfaces so as to match the local solute polarity. A multiscale description of the efficiency of THF:water pretreatment is provided: matching polarity at the atomic scale prevents lignin aggregation and disrupts cellulose, leading to improvements in deconstruction at the macroscopic scale.
    Print ISSN: 0027-8424
    Electronic ISSN: 1091-6490
    Topics: Biology , Medicine , Natural Sciences in General
    Published by National Academy of Sciences
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