Page History

...

Looking at the gamma PDF curve (Figure 2A) the alum dosage of 10 mg/L demonstrates an unusual behavior compared to the other doses; it has a very narrow distribution focused at a particular sedimentation velocity. It is suspected that the statistical functions we used to fit the data, did not fit the data right. Also, it could possibly be the case that this resulted from an unexpected presence of a large floc that might not have been representative of 10mg/L dosage but rather at the time the process controller recorded that reading a large floc happened to intersect. An option would be to either re-run the experiment or accept that we cannot fit it to the data. Otherwise 20 and 30 mg/L follow the trend well. From the residual turbidity graph (Figure 2B), there is also an unusual trend with the alum dose 40 mg/L; its turbidity unexpectedly peaks and results in an unusually high mean turbidity. (Can you speculate as to why this is the case?) In figure 2A, the alum doses 20 and 30 mg/L have wider distributions of floc sizes compared to those of other alum dosages. The wider distributions (Comment on why they have wider distributions. correspond to a wider variation in mean sedimentation velocities. (Can you comment on the average particle size? Are they higher or lower) Overall, there seems to be discrepancies between the data recorded in the two graphs. From the values of mean turbidity at settling state, from 10 to 45 mg/L the mean turbidity seemed to start at a value of .608 NTU then rise to about .725 at 25mg/L, then rises to .829 and then back down to .755 at 35 mg/L.

...