Effect of Gas-Liquid Two-Phase Flow in a Venturi Tube on Atomization and Transportation of Coagulant

Abstract

Compulsive sedimentation of soil particles using coagulant is one of the countermeasures for long-term turbid water in a dam reservoir. We used allophane as a coagulant, since it is considering that allophane obtained from nature has low environmental impact when it is added into the dam reservoir. The objective of the present study is to propose an atomization and transportation technique for allophane with a Venturi tube and to elucidate their mechanisms. We successfully visualized atomization behavior of allophane in detail and considered the atomization mechanisms. In addition, we confirmed that the turbidity of the water is improved by adding atomized allophane. In transportation experiment of allophane, it is found that allophane transportation is promoted in the condition of microbubble generation. Furthermore, visualization of allophane adhering to microbubble and following water flow is achieved, and it is suggested that allophane is transported by microbubble. Finally, we measured zeta potential of particles that is important factor in allophane transportation, and tried to elucidate the transportation mechanisms with evaluating the relationship with Sauter mean diameter of allophane.