I would like to quantify the OTR and the oxygen demand in different cultures and rpm of shaker by the method of gas in and gas out, but is not very clear which formulas used, and which measurement magnitude are replaces the variables in the formulas.
Hi Esteban,
You wish to calculate OTR and OUR during a fermenter cultivation I guess.
If it is the case, you can proceed with gas in gas out method (or the dynamic method).
There are different ways of estimation of OTR and KLa. I am attaching a word file showing one of these methods. There is an example at the end of the document that could help you.
If still not clear, I will send u an .xls file with another method I currently use.
Good luck
Amine
Hi Amine,
thanks for all! It was of great help. If it ready and is not to laborious for you, you can send me the xls file to evaluated? I will appreciate a lot.
I would like to compare the frask KLa with the 1 Liter fermentor.
in the file that you send me, in the formula the C*AL represents the oxygen concentration (in %) in the equilibrium, the CAL1 is the oxygen concentration (in %) at the initial of the experiment. CAL2 is the probe measuring % at each time.
In the Static Gassing Out Method (Unsteady State), C*AL would be =100%, CAL1=0%, and CAL2 would be the oxygen saturation % at each second, between the time needed it to go from 0% to 100%?
Thank again for your help!
Esteban
You cannot use the gas in/out for flask trials.
Just some tips: typically mass transfer of oxygen in flask is lower than in fermentern and the flask growth can be comparable only for cells with low growth rate (less than 0.1h-1) and it is not comparable for fast growing culture like E.coli.
I have studied energetic optimization and adaptive control of the dissolved oxygen concentration in aerobic fermenters having air flow and/or agitation rate as manipulated variable(s). The parameters from the usual KLa correlation were estimated through the recursive least squares algorithm with forgetting factor, thus allowing for on-line estimation of KLa in real-time. A sinusoidal disturbance was imposed to manipulated variables:
Thesis Controlo do Oxigénio Dissolvido em Fermentadores para Minimi...
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