Hydrodynamic stress capacity of microorganisms.
A new experimental method has been developed for estimating the hydrodynamic stress capacity of microorganisms. In a test apparatus, stable continuous cultures of three types of green algae and two cyanobacteria were exposed to well-defined hydrodynamic loads in a free jet. During and after the stress experiments the cultures showed a different response due to the damage in the jet. The results of these free-jet experiments with short stress exposure were compared to those of stirring experiments in which hydrodynamic load was continuously generated by a stirrer. In both kinds of experiments distinct critical stress values could be determined below which no essential damage of the microorganisms cultures occurred. A correlation between the critical stress values in free-jet and stirring experiments was found. It can be deduced that the free-jet data, expressed as critical volumetric dissipated energy, are suitable for the calculation of hydrodynamic stress to which microorganisms might be exposed in biotechnical plants without suffering damage.
Department B of Thermodynamics, Technical University of Munich, Arcisstrasse 21, D-8000 München 2, West Germany.
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Märkl