*** This version of Confluence is for testing only and contains a copy of content from June 29th 2026. No changes will be preserved. ***
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- Demo plant
- Cole-Parmer MasterFlex L/S peristaltic pump (x3)
- HF Scientific MicroTol inline turbidity meter
- Fischer Scientific magnetic stirrer
- Dayton AC/DC motor driven stirrer
- 1 L bottle
- 14 L bucket
- Connecting tubes, valves and fittings
Figure 1. Photograph of experimental setup.
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Figure 2. Flow chart showing experimental setup.
Procedure
Process Controller, a software based on LabView and written by Dr. Monroe Weber-Shirk, is used to automate the experiment and record the data. The automation routine, written by James Leung, controls the power to the stirrers and the speed of the pumps, calculated from the plant flow and residence time parameters. All other parameters, such as alum dose and pump tubing sizes, are fixed and preset in the routine. Process Controller also records turbidity data at 5 s intervals to a tab-delimited text file.
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The graph below shows the effluent turbidities for various plant flows, plotted against dimensionless time, which is real time divided by the residence time of the plant at that plant flow. This is done for ease of comparison between different experimental flow rates. The effluent turbidities plotted are the average effluent turbidity values obtained through several experimental trials.
Figure 3. Average effluent turbidity versus dimensionless time (number of residence times elapsed).
Most of the plots show a large spike in effluent turbidity near the beginning of each experiment. This is due to the experimental procedure and can be ignored. Between each experiment, the water in the turbidimeter was not cleaned out, temporarily resulting in an artificially raised turbidity at the beginning of each experiment. Thus, these spikes can be neglected in our analysis of the results.
The graphs show that as plant flow rate decreases, the effluent turbidity also decreases, until we reach 50 ml/min. At 25 ml/min, we found that the effluent turbidity is unstable but seems to be greater than that of 50 ml/min. From this, we conclude that the optimal flow rate of this flocculator and sedimentation tank is approximately 50ml/min.