
111Modes of Operation
Nonetheless, Shah and Lemlich (1970) showed that for a very deep bubbly
liquid (concentration was measured over a height of 1.73 m) that a solution
of crystal violet dye was approximately well-mixed just after bubbling com-
menced, but signicant segregation occurred on the time scale of about one
hour, when the concentration at the top of the column was four times the
concentration towards the bottom. Thus it is apparent that, if a deep bubbly
liquid is employed, the well-mixed approximation is not necessarily accurate,
and its deciency increases over time within a batch process. However, it is
likely that, in a conti