State-of-the-Art Approaches to Aerobic Fermentation Engineering

William M. Zadorsky

Ukraine State University of Chemical Engineering

Dnipropetrovsk, Ukraine

Pulsed aerobic bioreactors are addressed whose cyclic mode of phase interactions ensures strikingly high performance. Water purification, municipal/industrial sewage treatment, decontamination of hydrocarbon-polluted natural water, and fermentation are among their potential applications. Pulse frequencies are set commensurate with frequencies of some key levels in the system hierarchy, like microorganism family, contact element, contact stage, stirrer, apparatus. The focus is on revolutionary cocurrent reactors featuring multiple phase inversion. They combine optimum conditions for microbial biomass with high throughput, selectivity and compactness. Their flexibility enables stable operation and effective interactions at velocities in the respective ranges of 5-240 and 0.2-3.2 m/s for the liquid and the gas. The gas-liquid interaction times may be varied as desired via local liquid recirculation in any contact unit while biomass dwelling time variation is minimized. Other features include effective mass and heat transfer and elimination of stagnant sections, wall growth, or reverse mixing between contact stages. The principle may be readily applied to various flotation processes involving electroflotation, microscale bubbles and gas release on pressure drop. A stirred tank bioreactor is also provided in which process biokinetics provides a bias for control over stirrer power pulses and velocity, direction and energy of cyclic vortices in the liquid. The utility of air flow macropulsing is shown, and pulse parameters are formalized based on global correspondence principle found via systems approach to a biotechnological system. Possibilities to improve interface contact by use of air flow energy and aerosol techniques are covered.

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Information supplied by the Author January 1999.  Page last updated: January 19, 2004