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- Because the smallest particles dissolve fastest and are most prone to being carried out with the effluent due to their low settling velocities, they do not persist in the reactor even though it appears to be filled with solids. Since they have the highest surface area to volume ratio, the small particles are the ones that dissolve most effectively, whereas the larger particles, which may remain for a very long time, do not dissolve well enough to saturate the effluent within the residence time of the reactor. See hypotheses.
- Preferential flow paths form over time in the densely-packed reactor, so that eventually clean water is allowed to pass through with very little contact time with solid lime.
- Although the results from experiment 2 suggest otherwise, chemical/physical interference by calcium carbonate precipitate may still be part of the problem. See hypotheses.
Fig Fig 1. Experiment 3
This experiment used only the large reactor to test overloading the apparatus with lime, adding 200 grams of lime initially and whenever the pH dropped.