Microbubbles

Microbubbles
(click to play)
Windows Media Player file, 7.5 MB

The video shows a pressure cell with clear windows that allow viewing the inside of the cell. (The cell is made from 4” PVC flanges and other fittings.)

The cell is filled with water. With clear windows on the front and the back, it is possible to see all the way through the cell.

On the left of the cell is a pressure gauge calibrated in both pounds per square inch (psi) and feet of water.

At the beginning of the demonstration, the water is saturated with air (largely oxygen and nitrogen) and is at a pressure of 60 feet of water (26 psi), the same pressure that water would experience at 60 feet below groundwater surface. The water is clear, and it is possible to see all the way through the cell, even though the water contains dissolved oxygen (and nitrogen, argon, and other constituents of air) at over-saturation levels. The water is being stirred by a small jet of water from above; the resultant bubbles can be seen in the upper left quadrant of the window.

During the demonstration, the pressure is reduced, as can be observed on the pressure gauge. This reduction in pressure mimics the reduction in pressure in the treatment zone of a FreeOx™ well: the groundwater experiences a similar (though slower) decrease in pressure as it rises through the aquifer toward the inlet screen of the well near the water table. In the demonstration, as the pressure decreases the dissolved oxygen and other constituents of air come out of the water as micro bubbles. The water becomes cloudy, due to the micro bubbles, and it is no longer possible to see through the cell. The bubbles then rise, and the cell eventually clears.

In a FreeOx™ system, the water leaves the well at the deep screen, perfectly clear, yet containing over-saturation levels of oxygen. As the water rises toward the top of the aquifer, it releases the excess dissolved oxygen that was forced into the water by the high pressure at the bottom of the well. However, even at the groundwater surface, having released the excess dissolved oxygen, the water is still fully saturated to 1-atmosphere dissolved oxygen levels (approximately 10.5 mg/L, depending on atmospheric pressure and groundwater temperature); it is just no longer over-saturated.

The great advantages of FreeOx™ are:

1. The ability to force over-saturation levels of oxygen into the water with a low-pressure, low-energy process that involves no aboveground equipment.
2. The use of a recirculating well to over-saturate the water with oxygen several times.
3. The use of a recirculating well to push the oxygen-laden water to great distances from the wells, oxygenating all of the water in the circulation zone of the well.