A fermentation conditions were optimised on a laboratory fermenter of diameter and liquid height of 15 cm. The fermenter is equipped with a 5 cm diameter Rushton turbine operated at 800 rpm. The fermentation was run at turbulent conditions during agitation with a turbine impeller and therefore, the Reynolds number had to be maintained at the value of 1x10. Assuming that the density of the broth is close to that of water. The laboratory fermenter is then scaled up so the tank and impeller are 15 times the diameter of the laboratory equipment. The stirrer in the large vessel is operated at the same impeller tip speed as in the laboratory fermenter. a) What is the upper limit for the broth viscosity for the laboratory fermenter? [8%] b) How does scale-up affect the maximum viscosity allowable for maintenance of turbulent conditions? [7%]