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Abstract
Our team ran an experiment to investigate the affects of saturated air on floc blanket formation. To do this, our team paired with the Floating Floc research team, who supplied water saturated with air to the process. This experiment is meant to model the effects of having a pressurized system and the affects that change in pressure could have on floc blanket formation due to gas escaping from the influent water as bubbles. The idea for this experiment is derived from the need to model the affects of altitude change on an actual AguaClara treatment plant. For example, if a pipe were to pass into an area of decreased altitude pressure in the closed tube would increase Elevation changes can cause pressure changes in pipe. If air bubbles existed within the tube, this air would get absorbed into the water in the system. As , and as pressure increases, the concentration of dissolved gas water can hold increases. It is suspected that at higher pressures, there is more dissolved gas in the water. When the pressure is normalized to atmospheric pressure, these dissolved gasses can come out of solution in the form of air bubbles. As the pipes pass through an increase in altitude, pressure is alleviated and bubbles should escape.
Procedures/Overview of Methods
In order to deliver influent saturated air to the process, the Floating Floc team created a system which pressurized the influent water to a pressure greater than atmospheric pressure. At this double atmospheric pressure, the amount of air absorbed dissolved into the water is approximately twice the amount of air absorbed dissolved in the water at atmospheric pressure. This supersaturated water saturated with air was fed to the apparatus as influent water, where it immediately experienced a pressure drop to atmospheric pressure. While a pressure drop should result in the immediate formation of escaping air bubbles in the liquid, these did not form immediately. This is due to the activation energy required for the bubble to form, which is dependent on the surface tension of the bubble. In order to test bubble formation we observed the experiment qualitatively, looking for bubbles throughout the apparatus. We also monitored effluent turbidity, a value that would reflect the effect of the bubbles on tube settler performance floc blanket formation and particle settling.
Results
The hypothesis that absorbed air would be released in the apparatus was qualitatively observed by bubble formation. The adverse effects of bubble formation on floc blanket formation and effluent turbidity were supported qualitatively by the appearance of floc particles in the sedimentation tank effluent. (Were the floc particles attached to air bubbles? Unclear what you mean here) Also, large particles were sparse in the sedimentation column. (Could this be because flocs were being broken up?)
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