Utilization of a Microbubble Dispersion to Increase Oxygen Transfer in Pilot-Scale Baker's Yeast Fermentation Unit

In the large-scale production of <i>Saccharomyces cerevisiae</i> (baker's yeast), oxygen transfer, which is one of the major limiting factors, is improved by using high agitation rates. However, high agitation rates subject the microorganisms to high shear stress and caused high power consumption. A microbubble dispersion (MBD) method was investigated to improve oxygen transfer at low agitation rates and thus reduce power consumption and shear stress on the microorganisms. The experiments were conducted at the 1-liter level and subsequently scaled-up to 50-liters using a constant volumetric oxygen transfer coefficient (<i>k_La</i>) method for scaling. In comparison to a conventional air-sparged fermentation, the MBD method considerably improved the cell mass yield, growth rate and power consumption in the 50-liter fermentor. Cell mass production in the MBD system at agitation rate of 150 rpm was about the same as those obtained for a conventional air-sparged system agitatid at 500 rpm. Power consumption in the conventional air-sparged system was three-fold that required for the same biomass yield in the MBD system. However, at the 1-liter scale, the MBD system did not show any significant advantage over the air-sparged system because of the high power consumption.

Name thesis:degree_name

Master of Science

Level thesis:degree_level

masters

Discipline thesis:degree_discipline

Biological Systems Engineering

Department dc:contributor.department

Biological Systems Engineering

Grantor dc:publisher

Virginia Tech

Year dc:date.issued

2000

Author dc:creator

• Parakulsuksatid, Pramuk

Chair dc:contributor.committeechair

• Agblevor, Foster Aryi

Committee members dc:contributor.committeemember

• Cundiff, John S.
• Velander, William H.
• Yousten, Allan A.

• baker's yeast fermentation
• pilot-scale
• oxygen transfer
• microbubble dispersion

Statement dc:rights

• In Copyright

Licence dc:rights.uri

• http://rightsstatements.org/vocab/InC/1.0/

Dc Identifier Other

etd-05122000-00440044

OAI identifier oai:identifier

oai:vtechworks.lib.vt.edu:10919/32615