A flocculator is a device for water or effluent treatment, designed to slowly stir the contents of a tank of liquid (in a continuous flow-through process) to cause treated particles to agglomerate and form “flocs”. These loosely bound groups will settle far more rapidly than the smaller individual particles of which they are composed.
Flocculation usually takes place in a process between two treatment stages :
1) Pre-Treatment in which chemical additives are used to condition the process liquid, usually via a rapid mixing stage and then flocculation addition.
2) Separation in which the agglomerated solids are settled in a gravity system (eg conventional circular scraped settlement tank or a Lamella system)
Of considerable importance is the power input to the water, for the whole flocculation process hinges on this. Modern practices tend to quote G-Values. G is a measure of mixing intensity and is measured in units of sec-1, the higher the G-Value, the higher the intensity. Viscosity of the water/water effluent is a function of the formula to determine the G-Value, and viscosity changes with water temperature therefore it is important to determine the intended temperature range of the application.
Typical G-Values for flocculation duty range from 20 to 80 and a 3 stage flocculation process can be summarised as follows assuming a viscosity of 1.00cP (20oC water temperature) :
Stage 1 Flocculation G-Value : 70 sec-1
Stage 2 Flocculation G-Value : 60 sec-1
-Value : 45 sec-1
Note : G
-Values above 70 are not recommended as disintegration of the “flocs” could occur. *Download Data Sheet