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The mass of lime added was 17.89 gm. With this amount of lime, the upflow velocity chosen was 10.71cm/min, because the lime remained suspended and it was assumed the apparatus would run for a longer time according to the results observed in Experiment 1.
Figure - 1 Apparatus for experiment 2, using a pH probe
The initial pH reading was 12 and stayed that way for 2 hours. It gradually decreased to 8.85 (close to the pH of a solution that is fully saturated calcium bicarbonate) by the 24th hour.
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- With an upflow velocity of 10.71cm/min, the pH dropped from 12 to 11 after about 3.5 hours.
- After increasing the upflow velocity of 16cm/min (in order to enhance the lime mixing) and keeping all other parameters constant, no significant changes were noted.
Figure 2 shows the pH measures during the experiment.The results of the experiment are on an attached excel file. Excel Spreadsheet
Figure 2. Time vs pHCONCLUSIONS
Several problems were diagnosed from the above experimental results. They are as follows:
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