Hi, I have established a bioreactor parameters mammalian cell process with the following parameters:
Setpoint Deadband PID settings
1) pH- 7.0 0.1 1.0,5.0,1.0
2) DO- 60% 1 1.0,1.0,1.0
3) Stirer- 127 0
4) PO2 cascade with oxygen at (10ml/min)
5) pH cascade with base and (acid CO2 at 10ml/min)
The issue here is still the oxygen doesn't stop at the given setpoint and reaches around 120-180 % DO.
what can I do to maintain the DO to the specific setpoint. The total volume of reactor is 250ml and WV is 100ml.
The other issue here is the stirrer speed at what rpm I should be keeping it. Can we calculate the rpm of the stirrer according to the volume of the working volume of the reactor. Tip speed was calculated as- 0.0376m/s.
please let me know if more information are needed.
Dear friend Ashwin Naidu
Alright, buckle up because I am diving deep into the realm of bioreactor optimization! Let's tackle these issues:
**1. Dissolved Oxygen (DO) Control:**
**a. PID Settings:**
- Proportional (P): 1.0
- Integral (I): 1.0
- Derivative (D): 1.0
**b. Strategies:**
- Adjust the oxygen flow rate: Ensure the oxygen flow rate is appropriate for your setpoint. If it's exceeding, you Ashwin Naidu might need to lower the flow rate.
- Check for air bubbles: Ensure there are no air bubbles affecting the sensor's reading.
- Calibrate your sensor: Regular calibration ensures accurate readings.
**2. Stirrer Speed:**
**a. RPM Calculation:**
- Tip Speed = 0.0376 m/s (you Ashwin Naidu have this)
- RPM=Tip Speed/(πXImpeller Diameter)
**b. Considerations:**
- Cell sensitivity: Be mindful of the sensitivity of your cells to shear stress. Lower RPM might be needed for delicate cells.
- Mixing efficiency: Ensure sufficient mixing for uniform conditions throughout the bioreactor.
**Additional Tips:**
- **Monitoring Parameters:** Regularly monitor glucose, lactate, and cell density to understand the process dynamics.
- **pH Control:** Verify that your pH control strategy is effective. Fluctuations can impact DO levels.
**Suggestions:**
- **Experimentation:** Gradually adjust parameters and observe the impact on DO. Small changes can prevent drastic fluctuations.
**Remember, my guiding principle is continuous improvement!** Adjustments might need some trial and error. If you Ashwin Naidu encounter more challenges, feel free to share additional details for further assistance.
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