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TABLE 1: Shows the Lowest turbidity reached by specific alum dosage ranging 30 mg/L~55 mg/L during an influent turbidity of approximately 100 NTU.
(The table of data doesn't mean anything yet. First, graph data rather than creating tables of numbers. Second, the residual turbidity must have been observed at some time. That time corresponds to a settling velocity. So report the turbidity at a particular capture velocity! It appears that you didn't do actual data analysis, but that you somehow read numbers (perhaps from a graph) and then copied them down. That leads to subjective analysis. Use data analysis in MathCAD and create a graph and then show that in the wiki. This data is hardly any real justification for the alum dose of 45 mg/L. Why not use 40 mg/L?)

For the second experiment, the alum dose range was set to be from 40 mg/L to 110 mg/L varying with an increment of 5 mg/L (always leave a space between a number and the unit) and the influent On Oct 27, 2009, another experiment was conducted with the turbidity set around 500 NTU. Repeating the process implemented for the first experiment, this , flocculator length 2796 cm, flow rate of 5 mL/s, and alum dosage ranging from 10 to 90 mg/L. The data was run through Mathcad for an overview. However, unlike the previous experiment, looking at the gamma PDF graph (Figure 2) from Mathcad, the mean particle sizes did not vary significantly. With increasing alum doses, the floc size should have also differed. Yet comparing the size distribution for the lowest alum dose (40 mg/L) and the highest (110 mg/L), there was no comparable difference. In addition, reviewing the datalog, the approximate lowest NTU range also seemed to be similar (Table 2). From this analysis, we decided that either the accuracy of the result presented by this experiment was arguable or the alum dose of 40 mg/L was enough for effective flocculation. Since the dose of 40 mg/L seemed to have a similar effect as the higher alum doses, we decided to repeat this experiment with an expanded alum dose range to test even lower doses. An expansion of the range of alum dosages, from 10 mg/L to 100mg/L, was made to find the least alum dosage that will give effective flocculationto get a simplified graphic overview of the result.

In both graphs, the alum dosage 10 mg/L gave a comparably different result from the rest; it produced a significantly higher settling turbidity and a large amount of smaller flocs. The overall mean turbidity for this dosage was almost twice the following dosages. After the alum dose 50 mg/L, the mean turbidity seemed to be settling down to a constant value around 2.5 NTU.

FIGURE 3: The graph plots normalized turbidity vs. sedimentation velocity for each Alum dose ranging 40 mg/L~110 mg/L

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