Development of bubble column for foam separation

The foam separation of metal in model wastewater is performed by using two different bubble columns in a continuous operation mode. The equipment and operation conditions are changed, and the foam flow rate and metal concentr ation in foam flow are measured. The foam flow ratio (the ratio of foam flo w rate to the inlet one) increases with increasing gas velocity, with decre asing liquid velocity, with decreasing foam layer height and with decreasin g metal concentration in model wastewater. Metal enrichment (the ratio of m etal concentration in foam flow to that in inlet flow) shows the reverse te ndencies. When a draft tube is inserted in the bubbling layer, the foam flo w rate decreases. The enrichment is strongly governed by the foam flow rati o. Since the foam flow ratio is adjusted by means of the equipment and oper ation conditions, the metal concentration in foam flow is controlled to be a desired value.