Effect of Intermittent Addition on Turbidity Removal by Polymer Flocculant: Computer Simulation of Simplified Flocculation Model

Abstract

Since there are many factors which in uence the process of occulation by polymer occulant, the scienti c understanding of the occulation mechanism is still under discussion. We have proposed a simple bridging model which expresses occulation under various additive manners of the occulant and enables the understanding of qualitative trends of the occulation system. In the present study, from the simulated results based on the model and experimental data, we obtained the following knowledge: 1) the intermittent addition of polymer occulant gives better and reproducible turbidity removal; 2) the optimum dosage, which results in maximum turbidity removal in a given manner of addition, increases as the number of doses under the intermittent addition increases; 3) at a given amount of primary particles, the reproducibility at the optimum dosage of the 1-time dose is the worst among all results, irrespective of the additive manner. It could, therefore, be concluded that all these ndings are originating from the di erence of probability of bridging formation among particles under various additive manners.