What is oxygen transfer in bioreactor?
The oxygen transfer rate (OTR) through an interface is calculated as the multiplicative product of the mass transfer coefficient, the specific transfer area, and the concentration driving force. In a bioreactor for cell cultivation, oxygen is typically supplied by blowing air into the culture medium through a sparger.
What is mass transfer of oxygen?
Oxygen mass transfer in bioreactors involves many mass-transfer resistances. Among these, resistance of the gas–liquid interfacial area (a) and liquid film resistance (kL) are usually the rate-limiting steps for transfer of oxygen to or from the bulk of the liquid phase.
Why is mass transfer of oxygen important?
In many biochemical processes the oxygen supply to the broths is not enough to meet the demand of the microorganisms. Oxygen transfer is often the limiting factor in the aerobic bioprocess due to the low solubility of oxygen in the medium; so aeration is a critical factor in industrial aerobic fermentations [5-9].
How do you increase the oxygen transfer rate in a bioreactor?
For a successful aerobic cultivation, a good oxygen transfer is vital. It can be increased by: Creating a bigger surface of gas bubbles (kLa) by increasing gas flow and stirrer speed and by adding baffles. Creating a higher O2 concentration gradient by adding O2 to gasmix and increasing the pressure.
What are the factors that affect oxygen transfer in a bioreactor?
Key variables that impact kLa values
- Gas bubble size. When gas bubble size decreases, surface area and gas residency time increases, causing bubbles to stay in the culture longer.
- Mixing.
- Air flow rate.
- Properties of the liquid or medium.
How is oxygen transferred?
), or oxygen transfer occurs from the surrounding air to the bulk liquid via a liquid/air interface (as for a TF or a rotating biological contactor (RBC)).
Which factors control the oxygen levels in the bioreactors?
This article discusses the importance of aeration and available options to control the oxygen mass transfer coefficient (kLa) within a bioreactor….Key variables that impact kLa values
- Gas bubble size.
- Mixing.
- Air flow rate.
- Properties of the liquid or medium.
What is Standard oxygen Transfer rate?
The Standard Oxygen Transfer Rate (SOTR) is the rate at which the SOR is transferred in tap water at 20°C and zero DO. The Actual Oxygen Transfer Rate (AOTR or OTRf) is the rate at which AOR is transferred under field conditions.
What factors affect mass transfer coefficient?
value of overall mass transfer coefficient depends on the physical properties of fluid, reactor geometry, bubble size, bubble rise velocity, gas hold up, gas velocity and liquid velocity. The main interrelationships between factors affecting k L a L are summarized in Fig.
What is oxygen transfer efficiency?
SOTE: Standard Oxygen Transfer Efficiency SOTE is the measurement of how much oxygen is transferred by a given aerator in clean water under the American Society of Civil Engineers’ testing standards.
How do you calculate Standard oxygen Transfer efficiency?
The standard oxygen transfer rate (SOTR, g/m3 · s) is shown to be related to EI through a second-degree equation: SOTR = −11.5 EI2 + 2.27 EI (r2 = 0.951). The model applies over a wide range of diffuser types, diffuser densities, tank dimensions, and specific air flows.