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The second half of the experiment corresponds to a new addition of 100 grams of lime after 45 hours. Low readings are due to pH probe calibration. It can be observed that the increase in pH was dramatic and that both reactors remained above 12 for 19 hours (2.5cm tube settler) and 27.5 hours (5cm tube settler). Despite these promising results, the high fluctuation and the readings above 12.6 make them inaccurate and nullify the data. It is necessary to repeat the experiment when there is more certainty regarding the pH probe readings.
In order to ensure accurate pH readings, the pH probes were grounded to reduce the potential for high voltage fluctuations that damage the data acquisition system. In addition, when non experiments are running, pH probes are placed in a 4 pH solution to avoid lime clogging into the pH probe membranes.
Figure Figure 1A. Experiment 4 performance. First 40 hours. (pH vs time)
The purpose of this experiment was to decrease the upflow velocity in order to increase residence time. The mass of lime added was also decreased to 100 grams.
Figure
Figure 2A. Experiment 4 performance. Second 40 hours. (pH vs time)
The purpose of this experiment was to decrease the upflow velocity in order to increase residence time. The mass of lime added was also decreased to 100 grams.