Aeration hardware in stirred-tank bioreactors: Which device is specifically responsible for introducing air (or oxygen-containing gas) into the culture medium?

Introduction / Context:
Efficient gas–liquid mass transfer requires both gas introduction and good mixing. Different internals serve distinct roles; correctly identifying them is essential for troubleshooting oxygen transfer problems.

Given Data / Assumptions:

• Standard stirred tank with bottom or ring sparger.
• Agitation supplied by an impeller; baffles prevent vortex.
• Objective is to name the component that introduces gas.

Concept / Approach:
The sparger is a perforated ring or nozzle assembly that releases gas bubbles into the liquid. The impeller then disperses these bubbles; baffles improve dispersion by disrupting swirl.

Step-by-Step Solution:

Verification / Alternative check:
Bioreactor P&IDs and manuals label spargers as the gas inlet distribution device.

Why Other Options Are Wrong:

Common Pitfalls:
Assuming higher impeller speed alone increases oxygen transfer without adequate sparger design.

Final Answer:
Sparger.