Fig. 2
Foam reduction efficiency of foam-control system during rhamnolipids batch fermentation. Vf, the volume of the overflowing foam which streamed through the outtake in 1 min; Vb, the volume of residual foam streamed through micropore of circular ring in 1 min; Vtlf, left the foam sample stilly and recorded the liquid volume when all foam liquefies into liquid; Vilf, when foam passed through the foam breaker, most bubbles would collapse into liquid and record this liquid volume immediately