Compulsive sedimentation of soil particles using coagulant is one of the solution for long-term turbid water in dams that has a bad effect on the environment of downstream rivers. We focus on allophane as a coagulant. The purpose of this study is to develop an atomization and transportation technique for allophane with a Venturi tube. We utilized the microbubble generator with a Venturi tube to atomize allophane. First, we visualized internal flow of the tube and measured diameter distribution of allophane after passing through the tube. As a result, allophane was atomized as small as that stirred for 10 minutes by ultrasonic, and it is suggested that allophane diameter hardly depends on liquid flow rate in the tube. Second, we throw allophane after passing through the tube into turbid water. As a result, the sedimentation of soil particles was promoted, and the turbidity of water was improved with the passage of time. The speed of sedimentation of soil particles is found to dependent on liquid and gas flow rate and presence of a Venturi tube. Third, we did transportation experiment of allophane. It is found that allophane is transported greatest under conditions of microbubble generation. Furthermore, we measured zeta potential of particles, and tried to reveal the mechanisms of turbid water treatment and transportation.