TURBIDITY REMOVAL BY POLYMERIC FLOCCULANT - ANALYSIS THROUGH A SIMPLE BRIDGING MODEL

The turbidity removal by polymeric flocculant is simulated by a simple model. This model is based on a concept that both the polymer molecule and suspended particle have only two active sites through which they can be attached to each other, that is, the particles are joined together by bridging of polymer molecules resulting in floc formation. From the results of simulation, turbidity removal by polymeric flocculant has been found to be closely related to the manner of contact between flocculants and particles. In instantaneous contact between particles and flocculants, turbidity removal increases linearly to a maximum value and then decreases with increase of flocculant dosage. In the stepwise contact method, on the other hand, it is deduced that turbidity removal increases to a maximum value with increase of flocculant dosage and that this maximum value remains constant with further increase of flocculant dosage. Turbidity removal with respect to these two contact methods is studied experimentally using kaolin-nonionic polyacrylamide system, and a good correspondence between simulated and experimental results is obtained. Consequently, the stepwise contact operation is shown to be more effective for turbidity removal than the instantaneous contact operation. © 1980, Society of Chemical Engineers, Japan. All Rights Reserved.