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The table below shows actual measures of pH and alkalinity in AguaClara treatment plants in Honduras. To have high accuracy in the lime feeder design, the conditions of raw water in the laboratory will be simulated. The results in the table demonstrate a decrease of pH during the treatment process which is strongly visible on Cuatro Comunidades and Tamara plants.
Table 1: Water Quality in Honduras
Source: Honduras water reports, 2009
(What conditions are you going to design the lime feeder for (i.e. worse conditions)?)
PROPERTIES OF LIME
The pH of calcium Hydroxide or lime decreases with an increase in pH. (see figure 1 below) The temperature at the Honduran plants is generally in the range of 19-21 degrees C but during summers it can go up to about 27 degree C. This temperature change can change the pH of lime and thereby affect the working of the lime feeder and needs to be taken into consideration while designing the lime feeder.
Table 2: Changes in pH of lime with respect to Temperature changes
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