Experimental investigations of sedimentation of flocs in suspensions of biological water treatment plants

This contribution deals with the movement of flocs in suspensions, as they appear in biological water treatment (BWT) plants. The first part of the work deals with the description of a model BWT plant, followed by the definition of a problem. The greatest attention is given to the geometrical and sedimentation characteristics of solid flocs, key parameters for developing a fast numerical procedure for simulation of flocs' movements. An extensive analysis is presented of floc size distribution and their shapes. Based on the results of experimental investigations, the main geometrical parameters of the flocs are defined and calculated. The second part of the work deals with calculating floc density, based on free settling sedimentation tests and known empirical correlations for drag coefficient.