Team Members
Sara Schwetschenau
T. David McEvoy Gantt Chart - Dave
Kevin Borden Gantt Chart - Kevin
Rebecca ThompsonGantt Chart - Rebecca
Leah Buerman [Automated Flow Control Info]
Meeting: Mondays and Thursdays at 1:30pm and other times TBA
Motivation & Objective
The main objective for this semester is to create a reliable testing set-up that allows us to draw a conclusion about the efficiency of tapered flocculation in dynamic environments. The second main objective is to build and test a sedimentation tank in series with the floc tank. This will allow us to isolate what process needs to be improved. Does our flocculation model need to be improved or does our sedimentation design need alteration.
Semester Research Goals
As the semester has progressed research for the pilot plant has sort of split into three separate sections, data analysis, tank testing, and sedimentation tank design and construction. Goals have been split-up into these sections.
Tank Testing Procedures
There are several priorities that we have for this semester. Before initiating testing of the model, we have some preliminary goals to improve the laboratory setup.
It was determined that the openings between the sections of the flocculator were too small. We would like to make these openings larger by Friday, February 9.
In addition to these initial improvements and testing of the set-up, we also have research goals related to the tapered flocculation model. Our biggest goal is to establish a reliable experimental testing procedure. This method should include being able to visually analyze and classify, via a standardized reference, the flocculation in the tank.
Currently, sampling takes place in three adjustable locations within the tank. Before analysis in the turbidity meter, the water enters a long glass tube which is meant to act as a "miniature sedimentation tank". However, previous testing has indicated that a significant amount of floc reached the turbidimeters. We would like to improve the method of sedimentation before the water gets to the turbidimeter. In the old set up, only half of the tube settlers were submerged in the water. We belive the warm air was causing temperature gradients in the tube settlers, which could have been the reason that some of the flocs were getting into the turbidity meter before they had a chance to settle out. We would like to refit the tube settlers so that they will be fully submerged in the water. We want the tube settlers installed by the time the plant is running, which will hopefully be the week of March 10.
In order to double check the validity of data from the tube settler and turbidimeter combination, we have developed an alternate testing procedure in which grab samples are taken near the inlet points of the tube settler and allowed to settle for a short period of time. Data using this procedure will be compared to data from the turbidimeters as a validity check.
We would also like to implement better lighting in the plant, and develop more detailed procedure for quantifying floc size in various parts of the sedimentation tank. The light will also be put in place the week of March 10.
A main goal of the testing is to develop a profile of floc formation along the length of the large-scale tapered flocculator.
If necessary, we may augment the turbidity level of the incoming water to simulate the higher turbidity levels found in Honduras.
We would also like to test a set-up that includes obstacles between the baffles. The idea behind this modification would be to make the velocity gradients more even throughout the sections. Previous AguaClara research has indicated that velocity gradients were much higher around the turns than along the length of the baffles.
Data Analysis
Data analysis techniques build off of work done by Carol Serna in previous semesters. Data will be analyzed using MathCADD, and in some simple cases using Excel.
Comparative data of before and after tank improvements (cauking the tank, enlarging holes, and submerged tube settlers) is expected to be available.
Sedimentation Tank
One of out main goals for the semester is to install an AguaClara style sedimentation tank in line with the pilot plant flocculator. We would like to utilize a sludge blanket in the sedimentation tank to hopefully get us closer to the 1 NTU goal. This will be particularly difficult because we have a limited amount of energy head to deal with along with limited space available to us at the water treatment plant. We plan to have siginifigant design work done by March 14th so that we can begin construction sometime this semester. We are also looking into the potential to add a second sedimentation tank with lamella instead of a sludge blanket to get a comparative look at the benefit of the sludge blanket. We will need to design a connection system between the flocculator and the sedimentation tank that has sufficiently low shear values so as to not break up the flocs formed in the floc tank.
The design will be reviewed the week after Spring Break and if the design is deemed plausible construction will begin the following week.
Gantt Chart
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Past Research
In the Spring '07 semester, the pilot plant was designed and constructed.
in the Summer of '07, adjustments were made to the set-up and testing of the uniformly-spaced baffle design was done.
In the Fall '07 semester, a tapered-baffle set-up was designed, constructed, and installed.
History of past research and details of current research can be found on wiki page entitled Pilot Plant Construction and Past Research.
A summary of all of this past research and the current research going on with the pilot plant and the sedimentation tank can be found on the wiki Pilot Plant Construction and Research.