Before simulation, you need to do a straightforward chemical engineering analysis of mass transfer in your setup. What are the key factors (e.g. Henry's law constant, bubble transit time, bubble fraction)? Maybe find the relevant dimensionless groups ... This analysis will give you insight into the problem. The simulation of combined flotation (of the cells) + two phase separation (of the methanol) is going to be hard to make realistic & I wonder if it will help solve your problem. Have you tried removing the algae by centrifugation or filtration?

HI Alan,

Thank you very much for this. Yes, I have done the separation through centrifugation but I am looking at something different from the usual- kind of over ambitious, maybe. I agree with you on the complexity of the situation which is why I resulted to using this forum to seek help, and I believe  you have provided just that by confirming my fears. On the other hand, I want to do a methanol balance to start with and that seem to be a little tricky with Hysys, any help on that, please? I mean how do I quantify the amount of methanol that would escape with the air that leaves the top of the column, ignoring surfactants and algae and just concentrating on Water, Methanol, and Air. I must say that I am not that familiar with the software but would like to use it to support or query my results. Thanks a lot!