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THEORY AND INTRODUCTION
Tube settlers are settlers are designed to provide a low capture velocity to facilitate the removal of small flocs and hence lower the turbidity of flocculated suspensions. They are integral to the overall effectiveness and performance of the AguaClara water treatment plants, as they are involved in the final particulate settling mechanism and thus the final effluent turbidity. The experimental apparatus contains a controlled clay stock that is added to raw water and mixed to a turbidity of 100 NTU. This raw water is sent through rapid mixing with a fixed dosage of alum, which then enters a flocculator (where the floc is actually created). From this stage, the water enters a settling column where it forms a floc blanket. The tube settlers draw water from this column.
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