The profile of the inner-tubing gas pressure for a tubular membrane aeration system
was quantified. The correlations among the overall volumetric oxygen transfer coefficient
(k[subscript L]a), the inner-tubing pressure, the tubing tightness, and the gas throughput are
experimentally analyzed. A mathematical model was developed to describe the
underlying phenomena. The results established the base for comparison with other
aeration techniques.
A novel method employing in situ laser imaging technology to monitor bubbles and
cells, and analyze bubble size distributions in a micro-sparged bioreactor was developed.
The effects of bioreactor operations on bubble size distributions were determined with
following results:
1) Spargers with larger pores produced larger bubbles in most cases
2) Higher sparging rates resulted in bubble size increases up to 10%
3) Pluronic F68 shrank bubbles up to 30%. When the concentration of Pluronic F68
exceeded 1 g/L, no additional impact was observed.
4) Emulsion silicone antifoam up to 25 ppm had no impact on bubbles
5) Cell density (up to 22x10��� cells/mL) or culture age has no effect on bubble sizes
In multiple 1 5-L long-term high-density cultures of animal cells, the correlations
between sparging rate and cell damage for using 0.5 ��m and 15 ��m-pore spargers were
quantified. At cell density of 2x10��� cells/mL, sparging above 0.025 vvm using the 0.5-��m
sparger was detrimental to cells, while 0.054 vvm was detrimental for the 15-��m sparger.
A model was developed to predict the rate of cell death resulted from cell-bubble
interactions for high-density industrial animal cell cultures.
The effect of high superficial velocity of sparging gas on cells at the sparger surface
proved insignificant.
A new dissolved CO��� sensor proved to be reliable for long-term use in industrial
perfusion cell cultures. A novel method for the control of dissolved CO��� while
simultaneously maintaining DO��� and pH setpoints was developed. The continuous
control of dissolved CO���, DO��� and pH is achieved by simultaneously adjusting the total
sparging rate as well as the ratio of O���, N��� and CO��� gas contents. This control strategy
enables optimization of dissolved CO��� in industrial culture processes and allows for
improved cell growth and protein production. / Graduation date: 2002
| Identifer | oai:union.ndltd.org:ORGSU/oai:ir.library.oregonstate.edu:1957/32527 |
| Date | 17 December 2001 |
| Creators | Qi, Hanshi |
| Contributors | Jovanovic, Goran N. |
| Source Sets | Oregon State University |
| Language | en_US |
| Detected Language | English |
| Type | Thesis/Dissertation |
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