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The same experimental setup is used for each experiment described below. The system consists of four major processes: rapid mix, flocculation, floc blanket formation, and sedimentation. The turbidity of the raw water influent is monitored by a turbidimeter. From the raw water bucket, the influent travels to a coil that rapidly mixes the raw water and alum dosage. Next, the flow travels to the tube flocculator. The use of a tube flocculator allows for a more controlled flocculation environment as compared to flocculation with baffles. The flocculation design parameters are based on creating optimal conditions for floc blanket formation (please refer to Fall 2008 for tube flocculator parameters). From the flocculator, the water flows up through a 10 cm diameter column. A cone in the bottom of the column facilitates flow dispersion to create turbulent flow. It is here, in the column, that a floc blanket is formed. The height of the floc blanket is controlled by an effluent tube, located at the lowest desired floc blanket height (in our system 55 cm), which is opened or closed by a solenoid valve. From the top of the column, water is pulled through the sedimentation tubes and a final turbidimeter by a peristaltic pump. This system is fully automated by a program called Process Controller. Figure 1 below offers a schematic to illustrate the system described above.
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