Rob
Forum Moderator

OK, thanks. I need to tread carefully as I'm not supposed to stray into giving engineering advice.... 

Thinking about the mechanism. Oil droplets are present in the water, with a given volume fraction, and are probably small. Small gas bubbles are pushed in from the bottom from sparger bars.  The oil & gas stick & the whole lot goes out the top. In theory anyway! If we leave the scalar to one side. Are the oil droplets small enough to be considered as a species in the liquid?Â