Floe blanket clarification

It has long been known (see Ives ) that this is an insufficient criterion to cover all cases of flocculation, particularly those of floe blanket clarification, and that integration of equation 4.45 yields a dimensionless group GtC, where C is the floe volume concentration. Consequently, the very low G values (typically < 5 s ) in floe blanket clarifiers, are compensated by much higher C values (typically 0.1-0.2). It appears that the optimum GtC value lies between 100 and 500. This would agree with the value of Gt= 10 multiplied by C= 10 (GfC = 10 ) for paddle-type flow-through flocculators. 

Floe blanket clarification uses the floes themselves to form the fluidized bed, to enhance flocculation. In laboratory models a particulate suspension (such as polymer spherical beads) may be used to form the fluidized bed. In any case, the upflow rate is limited by the settling velocity of the fluidized suspension. This is affected linearly by the density of the suspension particles, and greater upflows (therefore more production per unit plan area of tank) can be passed through more dense particle suspensions. 

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