Abstract: A method of carrying out air oxidation comprises substantially continuously feeding liquid and air to an oxidizing tank (A) via a bubble forming device (D) which is fixed at the bottom of the tank, feeding a part of the liquid out of the tank via a lower port to a gas-liquid separating device (B) and then returning the liquid free from gas from the separating device to the oxidizing tank via the bubble forming device. Air separated from the liquid in the separating device is returned to the oxidizing tank and the finished solution is overflowed out from an upper portion of the oxidizing tank. The bubble forming device operates by feeding air into the lower chamber thereof via a nozzle which is aligned with and directed toward an orifice in a partition which divides the bubble forming device into two chambers. The liquid is fed into the lower chamber and the liquid and air are fed as a mixture through the orifice to impinge an upper wall of the upper chamber of the bubble forming device to more fully mix same.

Abstract: A bubble-forming device for gas-liquid contact which can be advantageously used for air oxidation in a liquid phase comprising a housing divided into upper and lower chambers by a partition having an orifice, a liquid inlet in the lower chamber, a gas inlet in the lower chamber having a nozzle directed upward toward the orifice, and having orifices in the side wall of the upper chamber such that gas-liquid mixture will be directed upward through the orifice in the partition toward the ceiling of the upper chamber and directed out the orifices in the side wall. A process for carrying out air oxidation in a liquid phase using said device by creating a large number of fine air bubbles in the liquid.