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3 edition of Agitation, mixing and mass transfer in simulated high viscosity fermentation broths found in the catalog.

Agitation, mixing and mass transfer in simulated high viscosity fermentation broths

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Published by University of Birmingham in Birmingham .
Written in English


Edition Notes

Thesis (Ph.D.) - University of Birmingham, Dept of Chemical Engineering.

Statementby Alan Douglas Hickman.
ID Numbers
Open LibraryOL14832880M

Malting and fermentation of maize: Maize was sorted to remove stones, dust and light materials, insect infested, broken grains, undersized and immature grains. It was cleaned thoroughly with water (3 times). Part of whole maize was soaked in water ( w/v) at 29 o C for six hours and germinated in a woven cane basket lined with a sterilized moist jute sack. The impact of mixing on the promotion of microorganism growth rate has been analyzed using a multiphase forced-circulation pipe-loop reactor model capable of identifying conditions under which it is possible to convert natural gas into Single-Cell Protein. The impact of mixing in the interphase mass transfer was found to exert a critical role in determining the overall productivity of the.   CFD has been applied to study heat transfer, combustion, and multiphase systems. Under the umbrella of multiphase flow regimes, the study of solid‐liquid systems in mechanical mixing vessels has focused on turbulent operations. Most of the studies have used Newtonian fluids (viscosity is independent of shear rate). The.


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Agitation, mixing and mass transfer in simulated high viscosity fermentation broths by Alan Douglas Hickman Download PDF EPUB FB2

Gas-liquid mass transfer, agitator power consumption, rheology, gas-liquid mixing and gas hold-up have been studied in an agitated, sparged vessel of diameter, T = m, with a liquid capacity of m\(^3\), unaerated liquid height = m.

The solutions of sodium carboxymethylcellulose used exhibit moderate viscoelasticity and shear thinning behaviour, obeying the power law over the range Cited by: 2. Agitation, mixing and mass transfer in simulated high viscosity fermentation broths Author: Hickman, Alan Douglas ISNI: Awarding Body: University of Birmingham Current Institution: University of Birmingham Date of Award: Cited by: 2.

Agitation, mixing and mass transfer in simulated high viscosity fermentation broths. By Alan Douglas Hickman. Download PDF (13 MB) Abstract. Gas-liquid mass transfer, agitator power consumption, rheology, gas-liquid mixing and gas hold-up have been studied in an agitated, sparged vessel of diameter, T = m, with a liquid capacity of m Author: Alan Douglas Hickman.

Viscoelasticity has also been used to study mixing and fluid flow in simulated xanthan fermentation broths [39], to study the effects of starter cultures on the properties of yoghurt gels [40] and.

AGITATION AND MIXING PRESENTATION OUTLINE-Definitions-Purposes of agitation • Agitation: It refers to the induced motion of a “homogenous” material in a specified way • Mixing: It is the random distribution, into and through one another, of two or more initially separate phases (Moderate viscosity) • High-efficiency impellers File Size: 1MB.

This can lead to high viscosities2 and related problems in mixing and mass transfer, even for cell densities corresponding to the region below OUR -- x given in Fig. (6 ~ 6 is, therefore, useless for high-viscosity fermentation liquids. For stirred vessels kLA drops at viscosities about ~ Pa s with/ars (Ref.

A few investigations have focused on aerobic fermentation systems in terms of mass transfer and mixing (Laakkonen et al., a, Laakkonen et al., b, McClure et al., ).

These studies revolve around a single operating point with regards to power input and in particular a fixed filling of the reactor which for fed-batch processes is known. of liquid liquid mass transfer coefficients with agitation speeds in mass transfer dominated reaction system for the extraction of -Viscosity [kg.m1.s-1] eff Reactors employing agitation generally demonstrate high mass transfer rates [1].

Hydrodynamic and oxygen mass transfer studies in bubble columns and airlift bioreactors, in Biotechnology Processes Scale-up and Mixing, (Eds Ho, C. and Oldshue, J. Y.), American Institute of Chemical Engineers, New York, p. 6 Aeration and Agitation Important factor in a fermenters Provision for adequate mixing of its contents Mixing in fermentation to disperse the air bubbles to suspend the cells to enhance heat and mass transfer in the medium All relate to Gas-liquid mass transfer 6.

The effects on mass‐transfer and overall mixing rates of varying impeller geometry and operating speed have been studied for flat‐bladed turbines in laboratory fermentors, in aerated aqueous solutions, and in unaerated and aerated suspensions (% w/v) of paper Agitation.

AGITATION AND MIXING OF FLUIDS Purpose of agitation: intensification of transport processes in agitated batch (heat and mass transfer) preparation of materials of required properties (suspension, emulsion) Examples of industrial applications: blending of two miscible liquids as ethyl alcohol and water.

This result suggests that decreasing the viscosity significantly affects the mixing and oxygen mass transfer efficiency in the fermentor under limited agitation and aeration rate [27], which are.

"Pulsed feeding during fed-batch Aspergillus oryzae fermentation leads to improved oxygen mass transfer." Biotechnololy Prog. 19, () Abstract Productivity in many fungal fermentations is detrimentally affected by high broth viscosity and consequent reduced oxygen mass transfer capacity.

Volumetric oxygen transfer coefficient (K L a) serves as a determinant of aeration efficiency of a bioreactor. Maintenance of Agitation K L a throughout the liquid is most important in aerobic submerged fermentation.

In fact K L a is influenced by several factors as described in the following sections. Broth viscosity. When working with medium to high viscosity broths, Rushton turbines permit an adequate agitation and mixing that result in an enhanced oxygen mass transfer that is key to the production of chemicals by fungi.

In the case of fumaric acid, high concentrations of oxygen in the broth yield high titers of the acid, but low productivities, while the. Bartholomew et at. () represented the transfer of oxygen from air to the cell, during fermentation, as occurring in a number of steps: (i) The transfer of oxygen from an air bubble into solution.

(ii)The transfer of the dissolved oxygen through the fermentation medium to the microbial cell. (iii) The uptake of the dissolved oxygen by the cell. Agitation, mixing and mass transfer in simulated high viscosity fermentation broths.

University of Birmingham. Ph.D. Shenfield, Stephen (). The mathematical-statistical methodology of the contemporary Soviet family budget survey. University of Birmingham. Ph.D. The rheology behavior of biological fluids particularly when the viscosity is high and rheology is complex, is an important issue to understand, particularly for studies in mass-transfer and for solving technical problems with mixing in stirred bioreactors.

In this paper, the use of a Swingstir® impeller during the fermentation of Aspergillus oryzae resulted in decreases from the parameters. Good mixing and aeration in high viscosity broths may also achieved by a dual impeller combination. The mass transfer coefficient and respiration rate have been determined in the shake flask for the growth as well as for biotransformation medium.

Yano H. Mixing of highly viscous simulated xanthan fermentation broths. the problems of high viscosity and poor mass transfer condi-tions. Viscous fermentation broths exhibit pseudo-plasticity and viscoelasticity owing to their changing uid rheology with the passage of fermentation time.

The non-Newtonian behavior of viscous fermentation uids impart detrimental effects on. heat transfer rates and excellent mixing.

In this system, a high number of variables affect the mass transfer and mixing, the most important among them are stirrer speed, type and number of stirrers and gas flow rate used.

The correct measurement and/or prediction of the volumetric mass transfer coefficient, (k la), is a crucial step in the design. These being they are cheap to install and operate. When scale up is required large mechanical agitators are impractical as the power required to achieve adequate mixing becomes very high.

Mechanical agitators are used for high viscosity cultures. Mass transfer. Good mixing and aeration in high viscosity broths may also be achieved by a dual impeller combination, where the lower impeller acts as the gas disperser and the upper impeller acts primarily as a device for aiding circulation of vessel contents.

69 Agitator design and operation Axial flow impellers - Intermig Impeller. mass transfer by a high shear stress [1]. Unfortunately, however, strong aeration and agitation cause foaming [6], loss of volatile metabolites [7,8], and cell damage [9], thus often provoking reductions in both, the productivity and cell growth.

An interesting alternative to minimize these effects. Most mass transfer studies in syngas fermentation using CSTR investigated operating parameters such as gas flow rate and agitation speed at a fixed working volume and mostly in unpressurised reactors [15,28,29].

Only a few studies have investigated the effect of elevated pressure on the mass transfer rates in a bioreactor. In batch fermentation, this can occur during the initial gr.

owth. phases while substrate concentrations are high • If this is a major problem, continuous or fed-batch fermentation methods should be considered • Product Inhibition • In batch fermentation, this can occur after induction of th.

e recombinant gene Shuler, p. rheological characteristics, being low-viscosity systems, which is convenient for high mass transport (10, 11). Some authors have mentioned that interfacial area for mass transfer is affected in fermentation broths contain-ing dispersed mycelia or pellets ().

However, no quantitative and/or systematic studies in this specific. Correlations for Volumetric Mass Transfer Coefficient in Xanthan Gum Solution. This experimental study is the first of its kind to report the correlations for k L a obtained for palm oil in xanthan solution.

Other organic phases were used in various fermentation broths and for a few bioreactor systems. Biochemical Engineering Journal 10 () – Oxygen transfer and mixing in mechanically agitated airlift bioreactors Yusuf Chistia,∗, Ulises J. Jauregui-Hazab a Institute of Technology and Engineering, Massey University, Private BagPalmerston North, New Zealand b Centro de Qu´ımica Farmacéutica, y 21 Atabey, Aptdo.Havana, Cuba.

The changes in viscosity (of 4 to 5 orders of magnitude) during culture [2] make this process very challenging with regard to efficient mixing throughout the fermentation [3]. Xanthan gum broths are highly pseudoplastic and exhibit a yield stress [2, 41 at high concentrations.

simulated broths have been used. The simulated broths were carboxymethylcellulose sodium salt solutions with the apparent viscosity in the domain of 5 - 26 cP. Owing to the difficulty of in-situ measurement of viscosity during the experiments, the viscosity was measured before and after each experiment using a viscometer of Viscotester 6 Plus.

Rate of oxygen transfer from bubble to liquid phase by equation, dCL /dt = kLa (C*-CL) Where, KL is volumetric mass transfer coefficient(cm h-1) a is gas/liq. interface area per liq. volume If O2 concentration, CL, is the limiting factor in cell growth, then QO2 is a strong function of dissolved O2 concentration CL (= mg O2/L).

Study of the Hydrodynamics and Mass Transfer Coefficient in a 2D Mimicked FT Slurry Bubble Columns for Alternative Clean Energy and Chemical Production Hjorth, S.A., Nienow, A.W., The performance of the Scaba 6SRGT agitator in the mixing of simulated xanthan gum broths.

Food & Bioproducts Process – Mixing of highly. Correlations for Volumetric Mass Transfer Coefficient in Xanthan Gum Solution. This experimental study is the first of its kind to report the correlations for obtained for palm oil in xanthan solution. Other organic phases were used in various fermentation broths and for a few bioreactor systems.

Amaral et al. () observed similar effect of oil on the oxygen transfer in the medium when they used olive oil as second organic phase in their study. They reasoned that the decrease of k L a by using olive oil was due to poor dispersion of oil. This could be caused by the properties of olive oil, such as higher viscosity and lesser density than water.

The authors thus recommend mixing times of 2 to 8 min. Shear in fermentors The lower limit on the speed of agitation of fermentation broths may be set by mass transfer considerations.

However, when tissue fragility or disruptions of mycelial pellets is a factor in design, agitation. Further, real high viscosity fluids often contain polymers or solids (such as fermentation broths, pastes, and colloids), and they are hardly ever Newtonian.

Miguel A. Galán, Physical explanation of the empirical coefficients of gas–liquid mass transfer equations, Chemical Engineering Science, /, 64, 2.

A mixing device, especially for a fermenter, capable of dispersing gas in a broth therein, in which a number of propeller mixers are provided on a vertically extending shaft.

The lower propeller mixer is a gas dispersing mixer having a hollow hub and open channels on the blades extending from this hub and tapering outwardly. At least one intermediate propeller mixer has some blades shorter.

Unformatted text preview: Aeration and Agitation Majority of fermentation are aerobic, therefore, required the provision of oxygen If the stoichiometry of respiration is considered, the oxidation of glucose may be presented as: C6H12O6 + 6O2 = 6H2O + 6CO2 g of oxygen are required for the complete oxidation of g of glucose As the oxygen is ~ time less soluble in water than is glucose.

Nevertheless, they also present major drawbacks, due to the unavoidable oxygen transfer limitations as a consequence of the high viscosity of the medium that they develop, which is believed to be related to the biomass concentration, growth rate and morphology.Fermentation processes are a central process step in industrial biotechnology.

The chemical, pharmaceutical, and food industries rely on fermentation to transform bacteria, yeasts or molds into valuable products and materials. Mechanical separation technology allows these fermentation products to be obtained from the fermentation broth.Bakker A., Benz G.T.

() Mixing in Industrial Fermenters. 10th International Biotechnology Symposium, August, Sydney, Australia. ABSTRACT Efficient fermenter operation depends on a variety of mixing related variables. Gas-liquid mass transfer.