Oxygen-transfer coefficient

Fermentation biomass productivities usually range from 2 to 5 g/(l h). This represents an oxygen demand in the range of 1.5 to 4 g 0/(l h). In a 500-m fermenter, this means achievement of a volumetric oxygen transfer coefficient in the range of 250 to 400 h"f Such oxygen-transfer capabihties can be achieved with aeration rates of the order of 0.5 (volume of air at STPA ohime of broth) and... 

Comparing this with the equation for Newtonian fluids shows that the oxygen transfer coefficient for non-Newtonian fluids is less sensitive to power input changes. Thus, more power input is required to reach the same mass transfer coefficient value than in a Newtonian fluid. 

Fig. 3.1. Effect of air flow rate on oxygen transfer coefficients, KLa. (1.1-1. min-1 = liters of air per liter of liquid per min)...

Dang, N.D.P., Karrer, D.A. and Dunn, I.J. (1977). Oxygen Transfer Coefficients by Dynamic Model Moment Analysis, Biotechnol. Bioeng. 19, 853. 

Sun, Y., andFurusaki, S., Mean Bubble Diameter and Oxygen Transfer Coefficient in a Three-Phase Fluidized Bed Bioreactor, J. Chem. Eng. Jpn., 21 20 (1988)... 

The overall oxygen transfer coefficient is defined as follows ... 

The value of the overall oxygen transfer coefficient, KLa = KLC>2, is central for the determination of the rate of oxygen transfer, F. Table 4.7 summarizes a number of empirical expressions proposed for the determination of K,a in gravity sewers (Jensen, 1994). 

TABLE 4.7. Empirical Expressions for the Determination of the Overall Oxygen Transfer Coefficient, KLa (20) = KLOa(20), in Gravity Sewers. 

Dague, R.R. (1972), Fundamentals of odor control, J. Water Poll. Control Fed., 44, 583—595. Dobbins, W.E. (1956), The nature of the oxygen transfer coefficient in aeration systems. In B. J. McCabe and W. W. Eckenfelder Jr. (eds.), Section 2.1 of Biological Treatment of Sewage and Industrial Wastes, Reinhold Publishing Corp., New York, pp. 141-148. 

Determination of reaeration relies on the measurement of the air-water oxygen transfer coefficient (Section 4.4.2). Measurement of this coefficient — the reaeration coefficient — in gravity sewer lines follows basically the methods that have been developed for and applied in rivers. Methods for determination... 

Jensen and Hvitved-Jacobsen (1991) developed a direct method for the determination of the air-water oxygen transfer coefficient in gravity sewers. This method is based on the use of krypton-85 for the air-water mass transfer and tritium for dispersion followed by a dual counting technique with a liquid scintillation counter (Tsivoglou et al 1965,1968 Tsivoglou andNeal, 1976). A constant ratio between the air-water mass transfer coefficients for dissolved oxygen and krypton-85 makes it possible to determine reaeration by a direct method. Sulfur hexafluoride, SF6, is another example of an inert substance that has been used as a tracer for reaeration measurements in sewers (Huisman et al., 1999). 

In Figure 8.3, the oxygen transfer coefficient, KLa, the flow velocity, u, the bulk water DO concentration and the DO consumption rate of the biofilm, ry, are all plotted versus the flow, Q, under steady state conditions in a gravity sewer pipe under the conditions given. 

KLa air-water oxygen transfer coefficient, reaeration constant (s-1, h-1 or... 

Oxygen transfer coefficient, 26 157 Oxygen transport, silver and, 22 657 Oxygen vectors, 45 716-717 Oxyhalides, 23 647-651... 

In a hollow-fiber-type membrane blood oxygenator, the blood flows outside and across the hollow fibers. The total membrane area (outside fibers) is 4 m . From the data on physical oxygen absorption into water at 20 °C, the following empirical equation (a) for the water-phase oxygen transfer coefficient (cm min ) in this particular oxygenator at 20 °C was obtained. 

Taguchi, H. and A. E. Humphrey, "Dynamic Measurement of Volumetric Oxygen Transfer Coefficient in Fermentation Systems," /. Ferment. 7ec/ z.(Jap.) 44 (1966) 881-889. 

K.H. Choi, W.K. Lee, Circulation liquid velocity, gas hold-up, volumetric oxygen transfer coefficient in external-loop airlift reactors, J. Chem. Technol. Biotechnol. 56 (1993) 51-58. 

DO = dissolved oxygen concentration kL = global oxygen transfer coefficient a = gas-liquid interfacial area per reactor volume q02 = oxygen specific consumption rate. 

This mass balance concerns the liquid phase, since oxygen must be dissolved in order to be used by the cells. Due to the difficulty in measuring the interfacial area (a), especially when oxygenation is carried out by bubble aeration, it is common to use the product of kL times a (kLa), known as the volumetric oxygen transfer coefficient, as the relevant parameter. 

IgE IgG IgM IL KLa KLH mAb PEG S-S TK tRNA Immunoglobin class E Immunoglobin class G Immunoglobin class M Interleukin Volumetric oxygen transfer coefficient keyhole limpet haemocyanin Monoclonal antibody polyethylene glycol Disulfide bridge thymidine kinase transcript of the RNA... 

Process identification and parameter estimation has been applied in water quality and wastewater treatment systems (7-9). The overall oxygen transfer coefficient can be determined on-line. The hydraulic dispersion has been identified by manipulation of the influent flow rate or the return sludge flow rate (9). 

As SCOUR is an alternative measure of biodegradable load, it has been illustrated in fig 7 for the same simulation. The SCOUR profile (fig 8) is closely related to the DO profile (fig 6). The latter, however, is directly measurable, and the oxygen transfer coefficient does not have to be estimated. 

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