OVERVIEW
Drinking water needs to have a pH of about 7. During the process of water treatment, alum is added to remove organic particles and clay in the process of flocculation. Alum decreases the pH of water making it acidic below the safety limit. Moreover, the sensitivity of alum doage and neccessary alum dosage is very sensitive to pH changes dramatically if in the entering water has a low pHand vice versa. This is often the case in many of the Honduran plants. For this reason it is imperative to ensure that the pH of the water entering the flocculator is maintained near 7. Lime ( Calcium Hydroxide) is an alkaline substance popularly used to neautralize low pH water. By devising a system (lime feeder) which will continuously supply a dose of saturated lime into the entrance tank, we can make the target pH of the water as desired.
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The figure above shows the apparatus used for the first trial, it consists in a tube conected with a water source regulated by a pump. The lime was added manually at the top.
Figure - 1 
Trial 2 and 3:
In these trials, Process Controller was utilized to automate the experiment. In addition, the apparatus was equipped with a pH probe whose values could be logged into the computer via the Process Controller.
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For this trial, distilled water will be used instead of tap water. In the picture below (figure 4), the ANC Control team can be seen carrying the distilled water tank on to the platform where the experiment is to be set up.
Figure - 4 
FUTURE TASKS
- Is is required to develop several trials with the new enmseble. The team will determine the amount of lime required to maintain a pH of 12 for 24 hours. In addition the team will evaluate the performance of the new emsemble, if it is necessary, the length will be calculated again.
- Simulate Honuran water conditions. Once the team will have the design working well with distilled water, a new experiment will be required to analyze the performance with a lower pH concentration.
- The team is also working on the calculation of required changes according with the natural cariation of flow rate at the inlet tank in the plant.
