Agitation and Aeration Questions

• Which of the following is not classified as an axial flow impeller?
• The Intermig impeller is
• To increase the oxygen transfer rate in a shake flask culture system, which of the following (s) is/are followed?
• Industrial paddle agitators turn at the speed of
• Detergent like substances produced by microorganisms during a fermentation will lead to
• Which of the following stirrer requires least amount of energy for same yield?
• Pure oxygen, if used instead of air will increase oxygen transfer rates because
• A cylindrical reactor fitted with Rushton Turbine has a liquid volume of 100,000 litres. It has an aspect ratio (the ratio of the channel height to the width) of 2:1. The diameter of the impeller should be approximately:
• Which of the following is correct for the off-centre impellers?
• Flooding is a condition/phenomenon which occur in a bioreactor when
• For aerated mixing vessels in an aqueous solution, the mass transfer coefficient (kL) co-relating power consumption (Pm) and fermenter volume (V) can be expressed as
• During fermentation, the saturation concentration of oxygen was reduced from 7 ppm. to 1 ppm. Which one of the following conclusions can be drawn?
• A fermentation system has a KLa of 3 s-1 and a C0* of 5 ppm of O2. If the bulk liquid is completely depleted of oxygen, then the oxygen transfer rate will be equal to
• Impeller damage can be minimized by
• In aerobic microorganisms cultures radial flow impellers are used because
• A fermentation system has a KLa of 3 s-1 and a C0* of 5 ppm of O2. If the bulk liquid is saturated with oxygen then the oxygen transfer rate will be equal to
• If the stirrer speed is too slow, bubbles will accumulate and coalescese under the impeller. This phenomenon is known as a
• A reactor has a total volume of 50,000 litres. If it has a headspace volume of 10,000 litres, then volume of liquid in the reactor will be
• Reynolds (Rei) number for the impeller is given by (where Di, stirrer diameter; N, stirrer speed, ρ, density of fluid and μ, viscosity of fluid)
• The advantage of axial flow impellers over radial flow impellers is that axial flow impellers