Gas injection and recycling apparatus and methods

A method for injection of oxygen gas or oxygen-rich gas into a body of liquid or wastewater using a floating oxygenator, the floating oxygenator including:

• a rotary hollow shaft vertically passing through a float, partially immersed in the liquid;
• an impeller attached to a lower end of the rotary hollow shaft, drivable by the rotary hollow shaft and immersed in the liquid, the impeller having a gas injection hole fluidly connected to a hollow of the rotary hollow shaft;
• a columnar structure, surrounding the rotary hollow shaft, mounted on a bottom side of the float and vertically extending into the liquid;
• a gas diffusion induction chamber formed by the columnar structure, the float and the liquid surface under the float;
• and a gas inlet passing through the float surrounded by the columnar structure for delivering an oxygen containing gas, the method comprising the steps of:
• disposing the floating oxygenator on a surface of the liquid (i) to form a gas diffusion induction chamber enclosed by the columnar structure, the float and the liquid surface under the float and (ii) to immerse the impeller into a body of the liquid;
• delivering the oxygen gas into the gas diffusion induction chamber from the gas inlet;
• and
• driving the impeller to rotate and generate a vacuum in the body of the liquid around the impeller, wherein the oxygen gas in the gas diffusion induction chamber is sucked into the body of the liquid through the hollow of the rotary hollow shaft and the gas injection hole of the impeller, where the oxygen gas is mixed and reacted with the liquid and undissolved oxygen gas rises up and is collected in the gas diffusion induction chamber for reuse.