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This experiment explored the impact of influent water saturated with air supersaturated with respect to atmospheric pressure on floc blanket formation and effluent turbidityperformance. This experiment involved collaboration with the Floating Floc Research Team, who supplied the saturated water that served as the influent water to the process.
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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 cloudiness of the liquid exiting the sedimentation tank effluentthrough the tube settler. It is possible that these air bubbles caused some of the flocs to break up. The observed cloudiness of the water in the tube settler could indicate the presence of small water bubbles, which could break up flocs. In addition, it is likely that these air bubbles disrupted the velocity gradient in the tube settler, which is assumed to be a convex velocity gradient whose peak is closest to the tube settler escape (What do you mean by tube settler escape? Also, how are these air bubbles disrupting the velocity gradient? I think more careful thought is needed here about what large air bubbles could be doing in the tube settler.) . This gradient broke up larger flocs resulting in smaller floc particles than expected. The velocity gradient controls the transport of flocs that enter the tube settler to the effluent for turbidity measurement. Floc roll-up is characterized based on a force balance. Due to the fact that smaller floc particles are entering the velocity gradient in the tube settler, the foce balance reveals that these particles are more likely to escape into the effluent, increasing effluent turbidity.
Quantitatively, data collected over twenty four hours showed an increase in effluent turbidity when comparing the experimental run with saturated air to the control experiment. We ran this experiment on both high and low floc blanket levels. In the high floc blanket formation state the floc blanket level is above the plate settlers. In the low floc blanket formation the floc blanket formation level is below the plate settlers. The presence of air bubbles could break up some floc particles and force floc particles up into the clarified effluent. Floc particles attached to air bubbles could potentially travel through the tube settler when they would normally settle out causing worsened performance.
Experiment 1 & 2: Low & High Floc Blanket Formations
Conclusion and Future Considerations
It was expected that these bubbles would disturb floc blanket stability (Again note the ways that these bubbles disturb floc blanket stability. Perhaps, you should also define what you mean by stability here.), permitting more floc particles to leave with the sedimentation column effluentthe release of saturated air as bubbles in the sedementation column would prevent effective floc blanket formation. The bubbles were expected to break up larger flocs and, create smaller, lighter flocs that would leave through the plate settler (due to a force balance velocity gradient analysis) and increase overall effluent turbidity. An increase in effluent turbidity and the appearance of bubbles in the apparatus supported this hypothesis in the experiment on low floc blanket formation. However, for the experiment on high floc blanket formation, the data was not consistent with this prediction. If AguaClara is considering designing additional plants undergoing elevation drops, results from this experiment should be considered.
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