Please note that the average effluent value from the 15.1 mm tubes at the high floc blanket at the lowest critical velocity is questionable...this value is not included in the results section Figure 1 (the graph) below and we should consider doing that trial again. where is do we have the data for the 12 mm tubes?
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The wider tube settlers, as expected, provided slightly more sensitive data. That is, the effluent turbidity was directly measurably impacted by changes in flow rate, floc blanket height, and tube diameter. The table and graph below illustrate the average effluent turbidity for the three diameters described in the methods section above.
Table 2. Results
Figure 1. Results
As the results show, the second lowest capture velocity for each diameter tube resulted in the optimum settling efficiency at the low floc blanket heightheights. The results also show a general trend of increasing effluent turbidity once the capture velocity exceeds 11.0 m/day. This indicates that the current capture velocity design to in the current plants is appropriate.
However, as the graph clearly illustrates, there are no well-defined trends between diameters and floc blanket height at the capture velocities where effluent turbidities are under ~.5 NTU. Perhaps this is because the effluent turbidity is exceptionally sensitive to disturbances when it is at such a low level.
what are the newest small tube data? this data could probably be reworked to fit better.
_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.
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