Foam generation behavior in a rectangular bubble column was experimentally examined. A partitioning plate was vertically inserted in the column and a blockading plate was horizontally placed on the liquid surface. The location of these plates was changed, and the flow characteristics and foam generation behavior (foam layer height) were measured. These plates promoted the foam growth. The foam layer height was strongly governed by the gas velocity and gas holdup in the riser and the disturbance of liquid surface. The foam layer was generated on the liquid surface of downcomer due to the liquid circulation flow, and the water content in foam was very low like that of a mousse. In the treatment of wastewater containing a surfactant, both the removal and concentration ratio were higher in the proposed column than in the conventional one.