Ximena's Individual Contribution Page

During the fall semester 2009, I am working with the Alkalinity Control Team. My team has an interesting goal related with a current issue into the drinkable water treatment plants in Honduras. The water conditions at the entrance of the inlet tank are not constant, that force the operators to change Alum dosage to run in a successful way the flocculation process. While Alum dose is changing, the water pH is subject to variations, even a small extra dose of Alum could ride the pH to the acid range. My team have assumed the challenge of create a lime dozer which will provide an easy and cost effective way to control pH variations within the water in AguaClara plants.

Fall 2009 Contributions

My tasks on the team include participate on all discussions about the ensembles and the planning of next steps, participate on the ensemble, configuration of the process controller and take periodical measures of the variables. Other activities include the filling of weekly minutes, Google calendar and team tasks every week. My current priory activity is to make the first version of the report and the teach in presentation.

Developed Activities

1. Attending informative and training sessions and practicing the contents with the project. During the first weeks I had an overview about AguaClara technology, I knew the facilities and I was familiarized with the lab, some apparatus, the way to work with the process controller and about the way to present my team advances.
2. Reviewing results from former groups, as starting point of the current experiment and I discussed with my team, with Professor Monroe and the teacher assistants about my doubts.
3. With the floating floc apparatus, the first challenge was to make it work, because it was not being used. This activity included process controller configuration, checking sensors, valves, pumps and all connections. With my team we carried on different trials until we got the system running successfully to prepare for the coordinated experiment with Plate Settler Spacing team. We needed to coordinate with them because the water was flowing from our apparatus to their one.
4. Once we were ready to start, we had a meeting with Professor Monroe, about the possibility to change our focus. I attended the meeting and I support the idea of the change. For me it is important to know that all effort in the project has a strong reason. With the change we are able to work and find a solution for an actual problem, the alkalinity stabilization.
5. In order to face the new goal, I found literature about lime and lime feeders. That information helped me to understand the differences among commercial designs and the new version of a lime feeder that we have to design. We have some constraints including avoid electricity use, looking for cheap materials, easy to find in Honduras, some design easy to construct and operate. The reviewed literature included the report of one team that assumed our same challenge in 2005; that document would be found on Research 2005/2006.
6. In a meeting with my team, I purposed to change the design for something similar to a clock mechanism to add solid lime instead of lime in suspension. We were discussing about the limited time that we have and we decided to exploit the knowledge that we received from the precious team. In conclusion, we opted for start on their last trial.
7. We wanted to know the actual conditions of Honduras water, so I read and summarized the information reported for Hoduras AguaClara team. The information was written in Spanish and I send the summary in English for my team mates. The summary can be found in ANC midterm report.
8. One of my team mates set the calculations from the former team in MathCad, we discussed his analysis and we brought some questions to Matt. Matt taught to us the way to improve our calculus file.
9. After deciding change the inverted cone design for the fluidized lime bed suspended in a tall column, as Professor Monroe's suggestion. I participated of the apparatus ensemble, the process controller programming and the calculations analysis.
10. Together with one of my team mates I run the first experiment consisting just in determine a good velocity to maintain a suspension lime. We tried different flow rates, and the best one was 85 ml/min where it was a good lime suspension without so much lime going out with the effluent. The analysis was visual, because at that moment we didn't have the pH probe, so we couldn't determine if that flow rate was also good to maintain the desired pH constant for one day. The results of the experiment can be found in ANC-Initial Experiment Spreadsheet.
11. Once we had the pH probe, we run other trials. I participated on the ensemble of the apparatus, the setting of the sensors and taking measures of the pH during the time the experiment was running. Results of the experiments are on ANC-Second Experiment Spreadsheet.
12. The next experiment consists in a diagonal column attached at the top of the vertical column, as Professor Monroe suggestion. I participated on the discussions about the ensemble, and attending the requirements for it (source of distilled water, cutting of tubes on the workshop, discussion of calculations).
13. Other activities include the filling of weekly minutes, Google calendar and team tasks every week. My current priory activity is to make the first version of the report and the teach in presentation.