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h1. Spring 2009 Turbidity Profiles
h2. Methods
* h3. Hot-swapping Baffle Configurations
Two adjustable baffle configurations were built this semester. Each consists of two 6' rows of baffles, one row for each of the first two channels of the flocculator. While one configuration (2 rows) is in the flocculator and being tested, the other configuration (which is not in use) can have its baffle spacing altered. Because that is possible, instead of needing to wait between experiments while baffle spacing is readjusted, the new baffle spacing can be ready on the second baffle configuration and the two configurations can be simply swapped. Then, while the next experiment is running, the first baffle configuration can have its spacing altered to be ready for the subsequent experiment. Since each configuration also has different length spacers (and new spacer of other lengths can be readily fabricated), flocculator arrangements where one channel has a certain baffle spacing while the other channel has a different baffle spacing, echoing the current plant design, can be tested as well. In previous tests, many data samples needed to be collected in one sitting to avoid having large fluctuations in turbidity, which required experimenting and determining new alum dosages, and often resulted in data that could not be compared between days of testing. The new adjustable baffle system will do much to ameliorate this problem by allowing the pilot plant team to perform experiments faster, and thus perform more experiments in a day.
* h3. PAC dosing
Polyaluminum chloride (PAC) is the coagulant of choice of the Cornell Water Treatment Plant as well as many other plants across the United States. According to plant workers PAC is much more forgiving than alum in terms of dosing and forms flocs better in colder water, which is important when testing in Ithaca. [Dosing with PAC|PAC Design] was set up at the Pilot Plant. Our goal was to collect turbidity profiles of the tank based upon energy dissipation (the spacing of the baffles). To facilitate this goal and remove a large source of potential error, we eliminated alum dosing in favor of dosing the same proportion of PAC that the treatment plant is dosing (the plant doses PAC in ppm of the total flow). This should make the profiles more comparable and the effects of baffle spacing more clear, since temperature and non-optimal dosing effects have been greatly reduced by adopting PAC.
h2. Calculations
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h6. Equation for energy dissipation:
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h6. Equation for flocculator residence time:
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Length of flocculator channel = 1.8288 m
K ~baffle~ = 4
Π ~cell~ = 4
w = .305 m
h = .764 m
| | *Q ~50~ = 50 L/min* | | | *Q ~100~ = 100 L/min* | | |
| *b (m)* | *ε (mW/kg)* | *N (#baffles/channel)* | *θ ~channel~ (residence time/channel) (sec)* | *ε (mW/kg)* | *N (#baffles/channel)* | *θ ~channel~ (residence time/channel) (sec)* |
| .051 | 1.507 | 34 | 484.9 | 12.06 | 34 | 242.4 |
| .076 | .306 | 23 | 488.8 | 2.445 | 23 |244.4 |
| .102 | .094 | 16 | 456.3 | .754 | 16 | 228.2 |
| .127 | .039 | 13 | 461.7 | .314 | 13 | 230.8 |
| .152 | .019 | 11 | 467.5 | 0.153 | 11 | 233.8 |
| .203 | .006 | 8 | 454.1 | 0.048 | 8 | 227.1 |
h2. Turbidity Profiles
| *Configuration* | *1st channel* | *2nd channel* | *θ ~flocculator~ (s) at Q ~50~*| *θ ~flocculator~ (s) at Q ~100~*|
| [1|PPF Spring 2009 Turbidity Profile Configuration 1] | .152 m | .152 m | 935.1 | 467.7 |
| [2|PPF Spring 2009 Turbidity Profile Configuration 2] | .076 m | .076 m | 977.6 | 488.8 |
| [3|PPF Spring 2009 Turbidity Profile Configuration 3] | .102 m | .102 m | 9127 | 456.3 |
| [4|PPF Spring 2009 Tubidity Profile Configuration 4] | .127 m | .127 m | 923.3 | 461.7 |
| 5 | .203 m | .203 m | 908.2 | 454.1 |
| [6|PPF Spring 2009 Turbidity Profile Configuration 6] | .051 m | .051 m | 969.7 | 484.9 |
| [7|PPF Spring 2009 Turbidity Profile Configuration 7] | .051 m | .076 m| 973.7 | 486.9 |
| [8|PPF Spring 2009 Turbidity Profile Configuration 8] | .051 m| .102 m | 941.2 | 470.6 |
| [9|PPF Spring 2009 Turbidity Profile Configuration 9] | .051 m | .152 m | 952.4 | 476.2 |
| [10|PPF Spring 2009 Turbidity Profile Configuration 10] | .051 m | .203 m | 939.0 | 469.5 |
| 11 | .076 m | .102 m | 945.1 | 472.6 |
| [12|PPF Spring 2009 Turbidity Profile Configuration 12] | .102 m | .152 m | 923.9 | 461.94 |
h2. Methods
With each different baffle configuration, spacers were placed on the PVC pipes to adjust baffle spacings. Spacers were changed to have different spacings between the baffles. While one experiment was running in the floccuator, an spare set of baffle system was being spaced apart to avoid wasting time. Two different flow rates, 50L/min and 100L/min, were used with each baffle configuration.
Tube settlers were placed along four different places of the flocculater to measure the turbidity. They were evenly spaced out from beginning to end in the flocculator. Tube settlers had to be filled with water before being placed in the water to avoid having air go into the pumps. The tube settlers would bring the water into the tubidimeters.The [turbidimeters were cleaned|Turbidimeter Maintenance] with each change in baffle configuration with distilled water and wipes. Turbidity would be recorded into the computer every 5 seconds. With the data that was recorded into the computer we were able to plot graphs finding out how the turbidity dropped throughout the floccuator with each baffle configuration.
h2. Results and Findings |
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