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Our team ran a typical experiment multiple times repeatedly to see how the effluent turbidity data fluctuated during the settling state in each experiments and to compare the data fluctuation between experiments. The experiment set up was an influent turbidity of 50 NTU, a flocculator length of 25 feet, and a G of 3.1 1/s. We repeated this experiment at least ten times in a row. We extrapolated the data from just the settling state (600 seconds), we found the average and standard deviation of the influent turbidity and the effluent turbidity separately at each second interval. We conducted this experiment for the typical position of the turbidimeter at the top of the settling column and at a new position of the turbidimeter at the bottom of the settling column.
Figure 1: Standard Deviations of the Influent and Effluent Settling Turbidities from 10 consecutive experiments using the same position of the settling column (top).
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These results definately show us some insights into our data. We see that the settling data in one experiment will not be the same as in the next experiment (when all variables of the experiment remain the same). From the data, it appears that there is no significant difference from having the turbidimeter position at the top or at the bottom of the column, except for the slight increase in the max standard deviation of the effluent settling turbidity.