Characteristics of Coagulants Dispersion in Full-Scale Pump Diffusion Mixers

Abstract

Recently, pump diffusion mixer has been introduced for the rapid and complete dispersion of a coagulant within a second before the metal hydroxide precipitate has formed. Pump diffusion mixer is an effective device for the quick dispersion of hydrolyzing metal salts. This research was conducted to investigate the coagulant dispersion distribution in the selected full-scale pump diffusion mixers (PDMs), and to evaluate their performance through a wet test experimentally. The wet test was to measure the fractional zeta-potential all over the cross section at a distance of 4.5D (D = 1,200 mm) from deflector in the selected PDMs on various conditions of the pressurized/main water inlet flow-rate ratios (pumping rates). From the wet tests, when the pressurized/main water inlet flow-rate ratio (pumping rate) was less than 2%, the injected coagulant was distributed unevenly and dispersed locally. On the other hand, in the case of 4%, the coagulant dispersion distribution was relatively even. Also, in the case of...