Description of work done by Rebecca Thompson and Narayana Pappu
Nara and Rebecca completed the majority of the work in the second half of the semester together. Therefore, it seems appropriate to write this page together as well. Rebecca and Nara developed the testing procedure for the turbidity profile tests and performed these tests. The data that was collected is very interesting and this experimental procedure will provide a nice metric to compare future flocculator set-ups. This testing method will allow the new team to distinguish the performance of the flocculator from the performance of the sedimentation tank, which will be operating in tandem. It also allows the user to understand in which part of the flocculator the majority of flocculation is happening, which will be useful for futher fine-tuning of the set-up.
A lot of time this semester was spent fully understanding the set-up, especially mastering the use of the process controller, and learning and developing the procedure to find the optimal alum dose. Additionally, many experiments were not successful. Reasons for failed experiments ranged from changing environmental conditions, in which alum dose rate determined during the alum increment test was not useful at the time of the flocculation profile test, to turbidimeter lines clogging and reporting false readings.
To see the results from the grab sample test, performed by Rebecca, go to the "Grab Sample" section under "Testing Setup Modifications" of this page.
To see the experimental procedure and results from the flocculator profile testing, performed by Nara and Rebecca, go to the "Developing Turbidity Profiles along the Flocculator" and "Results from Profile Testing of Tapered Flocculator Set-up Spring '08" sections of this page.
We hope that the "Future Work" section also found on this page will be useful to the new students who work on this project. In addition, written notes were taken during the experiments, and these notes will also be left at the water treatment plant for the use of future students
This semester, I have learned a lot about the pilot plant and its role in the AguaClara project. In the beginning of the semester, I worked with the team to make several modifications to the plant. These included enlarging the holes between baffle sections, cleaning the tank, and designing a support mechanism so that the tube settlers can be submerged in the water.
One of the concerns that we had with the data from previous semesters is that the tube settlers might not be a good approximation of AguaClara's standard sedimentation tanks. In order to verify the data from the tube settlers, I designed a grab sample procedure. The calculations for this procedure can be found here. The data from this procedure will be compared to the data from the turbidimeters to verify the validity of our testing procedures.
Also, I looked into data analysis techniques that I will use to analyze the data from the plant. The information on these programs and how I intend to use them can be found here. Unfortunately, due to the many changes that we made in plant set-up, we have not yet collected data. Most recently, overflow from the automatic flow control device has prevented data collection. I am excited to analyze data starting the week after Spring Break to observe the effects of the improvements we have made to the flocculator.
During the rest of the semester, I anticipate that I will be busy with building the sedimentation tank and analyzing data from the floc and sed tanks. Hopefully, we will be able to make a preliminary conclusion about wether a upflow clarifier-type sedimentation tank could help the AguaClara plants reach their goal of effluent water that is consistently less than 1NTU.