I am studying the effect of surface active agent concentration (1-50 ppm) on the hold-up and mixing time in an internal loop airlift bioreactors. the surface active agent used is "Sodium dodecyl sulfonate".
The problem is we have an overflow of foam even at lower concentrations of SDB.
you can use both mechanical foam breaker or alcoholic agents (if they do not affect on your results), decrease in temperature if possible. moreover, the source of foaming should be specified and then minimized. maybe your starting materials are vulnerable to form foam
Either use mechanical breakers or change surfactant if possible
You can use antifoam before you start your airlift fermentation or find the way to add it during the process. The best is to add during the process.
A few drops of high purity mineral oil (medical grade) may solve your problem. Only consider possible damage to the biota in use (adaptation / inhibition).
From your question it is not clear what your medium is. From actual fermentation, dead fermentation broth, pure medium, to pure water?
Assuming water, I have experience in an internal airlift using octanol. It is a surfactant, that hardly dissolves, in the past occasionally used as antifoam. It is very effective to use instead of your 'soap'. You may try any alcohol with a long chain, but I found octanol the best for the purpose.
When using a complex medium, antifoam in the form of oil like substances have to be added in a very controlled way. E.g. silicone oils or one of the modern commercial ones. But a major problem is the coalescence promoting effect within the liquid that may effect the aim of your research.
Mechanical foam breakup in citu is not easy to realise in an available airlift. One could consider an external one (via overflow).
Success
Dear Jai Ghosh, can you please elaborate on this method in the case of an internal airlift? Is the idea that the foam will be sucked in into the downcomer? Regards, Rob
Dear Ahmed, the concentration of octanol I used was 20 ppm, about the maximal solubility for octanol.
Dear Mr Ahmed,
Usually to knock down foams formed during fermentation process in internal loops air lift bioreactor, we use some drops of antifoam agent like organic silicone compound.
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