We are trying to scale up from 1 L to 10 L flat panel PBR using constant P/V value. However when we use
P/V= d x g x Uv,
We get;
2 L/min aeration in 1 L PBR and
14 L/min aeration in 10 L PBR.
The aireration seems very higher for algae, and we got lower yields compared to 1-L-PBR.
What should we do, can anyone suggest?
I suppose it depends on design of PBR. What is the depth of liquid in both reactors? Maybe it is not the same? What is light intensity per square meter of liquid surface? What is aeration rate per square meter? Is it equal on the whole points of liquid surface? If not, the scale up will be much more complicated.
Dear Irem,
I agree with V.V.Biryukov, I think "light intensity per cubic meter of liquid volüme and "aeration rate" are the most important parameters in such bioreactors.
Regards,
Selim
I am not agree that "light intensity per cubic meter of liquid volüme" is good scale-up parameter. You can have first fermentor, for instance, 2 meter hight of cultural liquid, and in second one only 5 cm. If volumes of liquid are equal in both fermentors, it means that the area of illuminated upper layes surface of liquid of first fermentor should be 40 times less than the area of second one. If you maintain light intensity on the upper surface of the first fermentor 40 times more than in the second one, the "light intensity per cubic meter of liquid volüme" will be equal for both fermentors. But it doesn' t means that the illumination of liquid layes in every parts of liquid volume are the same in both fermentors. They are different in different distance from upper surface of liquid even of each one fermentor. And the average illumination and consequently the average growth rate also will be different. I suppose, the design of PBR should pay attention on the depth of illuminated lays of liquid.
Something like concern also to aeration rate.
I am not saying that "light intensity per cubic meter of liquid volume" is your idea, that is my idea. But you also have to consider that flat type PBR's are not iluminated just from one side(top). We are talking about 3 dimensional illumination. So three-dimeansions are all affecting the illumination of the fermentation medium.
Best
Of course I know about 3 dimensional illumination. But even in this case the better scale-up parameter should be light intensity per square meter of liquid surface (my version) and not "light intensity per cubic meter of liquid volume" (your version). I mean the whole liquid surface which is contiguous to sources of light of any dimensions. This parameter is only one, it is not enough for the full success in scale-up. It is interesting to consider this problem in more detail.
Best regards
In my opinion, the parameter "Illuminated surface per cubic meter of culture" could be very helpful. Thus, we can scale-up this kind of PBR keeping constant this, handling the superficial velocity related to kLa, to find the relationship between these parameters and volumetric power consumption. You can check https://www.researchgate.net/publication/229404548_Hydrodynamic_and_mass_transfer_characterization_of_a_flat-panel_airlift_photobioreactor_with_high_light_path.
Article Hydrodynamic and mass transfer characterization of a flat-pa...
To my opinion, the only viable approach to upscaling of FP PBR which will allow to retain all the key parameters is modular approach. it means that you attain the target total volume by increasing the number of the modules all of which are of the ssame volume and geometry. The issue of aeration is really dependent on the design of the sparger and the vessel geometrу. To put it in a short way, what is good for 1-L vessel will not be as good for a 10-L vessel. An ideal sparger should give many small bubbles filling all the volume of the vessel. Make sure you have no stall regions. Good luck!
Multiplication of a module is indeed a good but often costly way to scale up. It is required that the basic module is optimal. Further, consider the economics: there is also an optimum in the number of modules and hence the size of the basic module.
Your system is a complex one with many subprocesses (mass transfer, heat transfer, flow, energy input (light, stirring (?)...) etc). When scaling, a regime change is possible and should be considered. You already choose a scale-up criterion, limiting you degrees of freedom. Consider to do a regime analysis.
https://www.researchgate.net/publication/276930620_Lecture_Notes_on_Scale_up_Scale_down?ev=prf_pub
Book Lecture Notes on Scale up / Scale down