SEDIMENTATION OF A POLYSTYRENE LATEX FLOC

An experimental study on the sedimentation of a permeable floc was conducted using a polystyrene latex floc having a consistent structure composed of uniform spherical particles. The combined measurements of a) the settling velocity (V(f)) of a single floc as a function of maximum distance between particles in the projected floc (D(max)) and b) D(max) as a function of the number of primary particles (i) were designed to evaluate the magnitude of permeability of a floc experienced during sedimentation. The measured values of log(V(f)) plotted against log(D(max)) indicated a linear relation over the entire range of measurements. The Debye-Brinkman equation as well as the proposed two-sphere collision model were applied to the analysis. The values of permeability obtained as a function of volume fraction defined in the ellipsoidal domain were found to be much higher, with values changing more rapidly than the value previously obtained for a swarm of spheres or fibres in a porous media which are considered to exhibit a homogeneous distribution of the solid throughout space.