Study of Floc Density in Micro-Cellulose-Aluminum Sulfate System

Abstract

The settling velocities of floc particles, which were made from dispersed microcellulose by using aluminum sulfate as a coagulant, were measured, and their buoyant densities were calculated by Stokes' equation. As a result, it was found that (1) the floc-density function, ρ_e=ad^-Kρ, proposed by Tambo et al., holds, (2) floc density increases with increase in agitation rate, (3) there exists a hysteresis phenomenon in the floc density with respect to the agitation rate, and (4) all the Kρ values observed in this system are nearly equal to 1. And it was shown that when the Kρ value is larger (smaller) than 1, the total projected area of flocs by light beam is increased (decreased) in the coagulation progress, and therefore, the Kρ value can be estimated by following the light-transmittance variation in the coagulation process.