Aeration experiments are conducted in the laboratory wide basin (10m×10m×1m). Compressed are is injected into the oxygen deficit water through the diffuser pipe at the bottom. The oxygen solution rate and the induced flow by the air bubbling are measured. The following points are made clear.
1. The induced vertical circulation flow is influenced by both the air supply rate and the orifice diameter. The maximum horizontal surface current in the basin can be estimated by the Kobus' equation. In the water area surrounded by diffuser pipes, vertical mixing is promoted well.
2. The oxygen solution is increased in rate owing to both the increase of the air injection rate and the decrease of the orifice diameter. KLa (overall oxygen transfer coefficient) in the basin can be predicted by the Eckenfelder's equation as well as in the aeration tank. Oxygen absorption efficiency (absorption/supply ratio) becomes lower, as the air supply increased in rate and as the DO concentration becomes higher.