Bioreactor kLa Oxygen Transfer Calculator
Bioprocess & fermentation engineering: Calculate volumetric oxygen transfer coefficient (kLa), Oxygen Uptake Rate (OUR), Oxygen Transfer Rate (OTR), and critical DO limit.
Fermentation & Oxygen Demand Parameters
Mass Transfer & Oxygen Balance
Recommended Tools & Equipment
Tested hardware and components for high reliability
Frequently Asked Questions
What is the volumetric mass transfer coefficient (kLa)?
The kLa (measured in reciprocal hours, h⁻¹ or s⁻¹) quantifies the rate at which gaseous oxygen dissolves across the gas-liquid bubble interface into the liquid culture broth. It combines the liquid film mass transfer coefficient (kL) with the specific gas-liquid interfacial area per unit volume (a).
Why does oxygen transfer become the primary bottleneck in high-density cell cultures?
Oxygen has a very low solubility in aqueous fermentation broths (~7 to 8 mg/L at 37°C in air). A dense bacterial culture (e.g. 50 g/L DCW) consuming 8 mmol O₂/g/h depletes the entire dissolved oxygen reservoir in less than 30 seconds unless replenished continuously by vigorous agitation and microbubble sparging.
How can kLa be increased during a fermentation run?
Process engineers increase kLa by increasing impeller agitation speed (which shears bubbles into smaller diameters, increasing interfacial area a), increasing gas sparge flow rate (VVM), raising vessel head pressure (boosting C*), or supplementing sparge air with pure oxygen gas.