Energy efficiency comparison: for the same target yield in aerobic cultures, which stirrer type typically requires the least energy input under comparable conditions?

Introduction / Context:
Modern axial-flow impellers such as Intermig are engineered to improve gas dispersion and oxygen transfer at reduced power per unit volume compared with classic radial turbines. Selecting the most energy-efficient design can lower operating costs and heat loads while maintaining productivity.

Given Data / Assumptions:

• Comparable tank sizes and aeration rates; same process yield objective.
• Operation below flooding; standard submergence and baffles.
• Yield constrained primarily by oxygen transfer and mixing quality.

Concept / Approach:
Intermig impellers provide strong axial pumping and enhanced bubble breakup with lower specific power than Rushton turbines for a given kLa. Compared with generic disk or unoptimized MIG variants, Intermig designs often achieve required transfer at reduced rpm and torque, improving energy efficiency while limiting shear damage to cells.

Step-by-Step Solution:

Verification / Alternative check:
Vendor and literature kLa–power correlations routinely show axial designs outperform radial turbines for aerobic cultures with similar gas rates.

Why Other Options Are Wrong:

• MIG/disc: typically higher power at same kLa compared with Intermig designs.
• Rushton turbine: effective disperser but usually higher power demand.
• Pitched-blade at 90° acts radial; energy-intensive for gas dispersion.

Common Pitfalls:
Assuming one impeller fits all; ignoring broth rheology and gas rate when comparing efficiency.

Final Answer:
Intermig.