Dynamic pressure method for kla measurement in large-scale bioreactors

Area of Science:

• Chemical Engineering
• Reaction Engineering
• Mass Transfer

Background:

• Accurate measurement of the oxygen transfer coefficient (k(l)a) is crucial for optimizing aerated and agitated reactors.
• Existing dynamic methods for k(l)a determination can be prone to significant errors due to gas phase non-idealities and interfacial transport phenomena.

Purpose of the Study:

• To propose and validate a novel dynamic method for k(l)a measurement that mitigates errors associated with non-ideal gas mixing.
• To demonstrate the reliability and applicability of the proposed method in comparison to established techniques.

Main Methods:

• A dynamic method involving a ~20% change in total reactor pressure, inducing a simultaneous change in oxygen concentration within all bubbles.
• Validation through comparison with a standard dynamic method (oxygen absorption in a degassed liquid) and the steady-state sulfite method.
• Testing oxygen probe signal independence from pressure variations.

Main Results:

• The proposed pressure-based dynamic method effectively suppresses errors caused by non-ideal gas mixing, unlike conventional dynamic methods.
• Reliable k(l)a values were obtained, validated against established methods.
• The method is suitable for large-scale reactors and can utilize air, not just pure oxygen.

Conclusions:

• The dynamic pressure method offers a more reliable and robust approach for k(l)a measurement in aerated and agitated reactors.
• This method provides a significant improvement over existing dynamic techniques, reducing potential errors.
• Its suitability for industrial-scale applications and use of air broadens its practical utility.