I am suffering of high air percentage under ongoing anaerobic bioreactor. I tried with CO2 flush for couple of hour but it did not reduce effectively. Higher air level is killing my consortium. I ensure air leakage at all the ports and tubings junctions manytimes but did not work. Please help if somebody has an idea over it.
I would like to know from experienced researchers that air percentage belongs how much dissolved oxygen?
It is really strange to see high oxygen level under anaerobic conditions. Positive pressure in anaerobic reactors due to methane generation may prevent air leakage.
Addition of sulfide or production from sulfate reduction may help to keep oxygen at low concentration. But sulfide concentration should be low enough not to kill the anaerobic microorganisms.
Thank you dear Sahinkaya for your valuable informations. Strange is that, there is no change in redox value (-163.00) when O2 levels changes significantly. It fluactuates between 30-90.
There seems to be a leakage somewhere. It can be also very effective to flush with N2 (higher flow rates). Do you close the exit gas exhaust after flushing ?
Thanks Eric for your answer but then why redox value does not change. I do not close exit gas port after flushing. it is connected with a device measuring gas amount and thereafter is open to exit.
I agree with Eric, there should be a leaking somewhere. However, the values of redox indicates that you are not achieving anaerobic conditions yet. I suggest to check for contamination and to calculate the specific growth rate of the organism you use everytime you start the process. pH value might help you with the redox value.
No I do not gassing with N2. Once I reduce with CO2 until I get good redox value thereafter I stand it without supplying any gas.
Well I do not know your setup (Bioreactor, gasanalyzer, ...) but gassing with N2 during the whole process will allow you to:
- remove the O2 in the culture
- Make sure it doesn't come back through the exit gas
- have a precise reading of the gas analyzer. YOu know how much gas comes in (flow + compositon, in this case 100%N2) and you know the composition in the exit (gas analyzer)
Thank you for your answer Eric. I will improve my setup as per you suggested.
commonly to made the anaerobic condition is using N2..u can use N2 in the beginning the process (purging)
Dear Mr. Anil
After stelization during cooling down you purge only with N2 this will complelely remove the O 2. Furthe you want to control you can add sodium sulfite in PPm level after testing in shake flask level .
Best wishes
Dear all,
I have a similar problem in my anaerobic fermentations (glucose fermentation by C.beijerinckii). I flush the fermenter with N2 (0.5 l/min) entire time and stir.
I prepare my anaerobic media accordingly so that there is no dissolved oxygen in the begining of the fermentation. However, during exponential growth phase, dissolved oxygen level increases drastically, up to 60%. The problem is not the probe nor the equipment. I observed the same pattern in different setups (Aplikon fermenters and microreactor fermentations).
Does anyone experience a similar thing?
Regards,
- Badges
- Science topic
- Similar topics
- Engineering
- Thermal Engineering
- Thermofluid
- Fluid Mechanics