Page History

...

There are two important graphs that give the best overview of the experiment: the gamma PDF graph and the residual turbidity graph. The gamma PDF graph shows the probability of reaching a certain floc size for each run of experiment with varying alum dosage. The y-axis represents the probability and the x-axis represents the floc size. The residual turbidity graph is the gamma PDF graph focused at a certain range of sedimentation velocity. We chose this range based on our knowledge on capture velocity. Capture velocity is the minimum speed flocs must be in for them to settle in the sedimentation tank; any particle with a smaller velocity than this will not sink. Given that the capture velocity is 0.12 mm/sec, the residual turbidity graph focuses on the flocs that fail to reach this velocity. The turbidity from these particles shows the resulting turbidity produced after flocculation.

On November 12, 2009, an experiment was conducted with the turbidity set around 5 NTU, flocculator length of 2796 cm, flow rate of 5 mL/s, and alum dosage ranged from 10 to 50 mg/L.

The data processor was unable to fit the sedimentation velocity vs. turbidity curve into a gamma pdf graph (Figure _A), because the trend of our mean turbidities was not following a gamma distribution (Figure _B). We suspect that it could not fit because of a low influent turbidity of 5 NTU, and how our lowest mean effluent turbidity was less than ideal at 1.978 NTU.

On November 11, 2009, an experiment was conducted with the turbidity set around 25 NTU, flocculator length 2796 cm, flow rate of 5 mL/s, and alum dosage ranged from 10 to 50 mg/L.

...