Page History

...

The data was analyzed using the same methods as in Experiment 1.

However, since the optimal alum dosage for 100 NTU water has been well characterized by previous experiments and our the interval our data identified (see Results and Discussion) generally agreed with the known value of 45 mg/L, we did not continue with the second test at 100 NTU to narrow the optimal dose range and instead tested 500 NTU water. For the 500 NTU water, we maintained the same flow rate of 5 mL/s and flocculator length of 2796 cm. However, this time we varied the alum dose from 40 mg/L to 120 mg/L in increments of 10 mg/L. We then analyzed the data using the same methods as before.
We plan to continue our investigation of alum dose by performing a second experiment with 500 NTU water to find optimal dose based upon the best interval from our previous experiment. We will then repeat the process of varying alum dose over large intervals, and then narrowing to an optimal dose for 5, 25, 50, 100, and 500 NTU waterwater at extended flocculator lengths of 5592 cm and 8388 cm, or double and triple the length of the current flocculator.

The following Process Controller Files were used for the 100 NTU and 500 NTU tests.
100 NTU Test
500 NTU Test

Results and Discussion

To find the ideal alum dosage for a certain influent turbidity, there are several qualities that must be considered. First, the resulting floc size should be large enough so that by the time it reaches the sedimentation tank, it will weigh enough to sink and settle out. Second, the resulting NTU must be small indicating an efficient flocculation/sedimentation process and clean water, and third, the alum dosage should preferably be low to save cost.

...