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We expect to see failure in the lower diameter tubes with the high Vc values because the flocs have a smaller area over which they can settle. The smaller diameters are expected to with flocs more quickly, and are less likely to have flocs waste out of the tube as the flow state is running.
Results
Priminary Preliminary experiments have been conducted for the purpose of determining the appropriate time interval for the flow and increment states, as well as determining which Vc and floc blanket combination cause failure. Based on these preliminary findings we are modifying the experiment to produce quality results in an efficient manner.
The plot below displays the effluent turbidity vs. critical velocity graphed on a semi-log plot. Each flow state was run for 6 hours, however, the floc blanket was at the high setting of 60 cm, as opposed to the desired low setting, due to air blocking the flow through the solenoid valve. There were also error in both the initial calculations of the flow rate and the tubing size. Instead of testing at a Vc range of 5 to 20 m/day a much higher Vc range of around 39 to 131 m/day. The results are display in the graph below.
Graph 1 The average effluent turbidity of the 9.5 mm tubes at a high floc blanket, with very high Vc values.
The graph clearly indicates that at the first Vc, the 9.5 mm tubes performed very well, with effluent turbidities around 0.5 NTU. The next three Vc settings result in very high effluent turbidities, over 100 NTU over the influent. This high values are most likely cause by a combination of extremely high Vc and the tubes position in the floc blanket at the upper height of 60 cm.
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