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The sedimentation process, which is completed directly after the floc blanket, is the final separation process of water purification. By the time the water enters the tube settlers, the turbidity has been dramatically reduced by the floc blanket. As seen in the figure below, the apparatus allows for independent control of the flow rates through the floc blanket and the tube settlers because of the additional waste outlet just above the floc blanket. The water flows up through the six tube settlers and manifold, through a turbidity meter, and is wasted. This flow is controlled by the same pump circulating alum to the system. In order to maintain a steady flow, a buffer may be utilized.
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