| abstract |
System, method and apparatus for diffusing gas bubbles into a body of water such as a pond, lagoon or basin (26). A small amount of water is continuously removed from the bottom of the body of water by one or more counterflow gas lift diffusers (20). This small amount of water is flowed down underground, has gas bubbles introduced into it, and is then returned to the body of water. The quantity of water removed and treated in this way is a small fraction of the total body of water in the pond, lagoon or basin. The ratio of (1) the volume of the body of water to (2) the total volume of the channels through which the water flows downward, and then back up into the body of water, is at all times at least about 10:1. In the broadest form of the invention, a gas diffuser (54) introduces gas bubbles into the water in the return channel (36) at a level at least about 2 feet below the bottom of the body of water. Improved results are obtained if this distance is at least about 3 feet, and it is preferred that it be at least about 5 feet. |