Recycling of gas in confined plunging liquid jet reactor

A method of recycling unused gases in a water aeration process, the method comprising:

• providing a confined plunging liquid jet reactor system comprising:
• a fluid reservoir containing water;
• a first outlet line in communication with a bottom of the fluid reservoir;
• a pump in communication with the first outlet line;
• a first inlet line in communication with the pump;
• a nozzle located at a top portion of the fluid reservoir and in communication with the first inlet line;
• a hood located beneath the nozzle, wherein lower ends of the hood are located at a surface layer of the water;
• producing a water jet at an outlet of the nozzle by recirculating the water from the first outlet line through the first inlet to the nozzle via the pump;
• entraining air in the water jet as the water jet flows from the outlet of the nozzle to obtain an entrained air water jet;
• entraining oxygen in a first portion of the entrained air water jet to obtain an entrained oxygen air water jet;
• flowing the entrained oxygen air water jet into the water in the fluid reservoir thereby forming small water bubbles as the entrained oxygen air water jet penetrates into the water;
• forming large water bubbles as the small water bubbles ascend toward the surface layer of the water;
• and
• recycling unused gases under the hood by flowing the unused gases toward the outlet of the nozzle, thereby entraining the unused gases in the entrained air water jet.