Abstract
Behaviors of colloidal flocs are largely dependent on the formation of flocs. In other words, it is the floc that is usually the unit of motion in a natural water environment, water and waste water treatment plants and industrial process. So far, the geometrical model of fractal structure derived from the concept of cluster-cluster addition is the most accepted and useful method for describing floc structure. Rate of sedimentation and rheological properties can be described with the help of fractal dimension (D), which is the function of the number of contacts between clusters (Nc). It is pointed out that the determination of D in relation to various flocculation conditions is the most important subject to be analyzed. The permeable properties of floc structure remains to be worked out in the future.
