Lateral mixing of shallow liquid pools by air bubbling

The lateral mixing of water in a shallow rectangular tank (length 225 cm, w idth 56.5 cm, depth 13 cm) under the action of bottom-stir plugs has been s tudied. The process has been measured and video-recorded, using an acid-bas e reaction with indicator to show the flow patterns. It is concluded that i n spite of the very low depth/width ratio in the tank, lateral mixing can b e. achieved quite efficiently using certain configurations of plugs which p romote lateral circulation. With the best configuration, a mixing time of a bout 3.5 min could be achieved using either 4 or 6 plugs. The specific powe r dissipation rate was very low (0.0044 W/kg). The mixing time was essentia lly the same with 4 or 6 plugs provided the total gas flow to the plugs was the same in the two cases. Tests with intermittent blowing of the plugs di d not show any improvements over steady operation.