CHARACTERISTICS OF THE SLUDGE PARTICLES IN REMOVAL PROCESS OF RADIOACTIVE CESIUM FROM OCEAN SLUDGE BY DECOMPOSITION SYSTEM WITH CIRCULATION TYPE USING MICRO BUBBLES AND ACTIVATING MICROORGANISMS

Abstract

The Fukushima nuclear accident of March 11, 2011, soil and water had been contaminated by
radioactive cesium. Moreover, radioactive cesium was found in the ocean sludge in Tokyo Bay flowing from
rivers. Cesium which is adsorbed to the sludge cannot be easily removed. One of the authors developed
decomposition and purification system, a circulation-type system by micro bubbles, that is, by creating
aerobic state, aerobic bacteria are activated resulting to decomposition and purification of ocean sludge.
Based on the hypothesis that radioactive cesium is adsorbed on the surface of the sludge deposition. It is
considered cesium can be eluted after decomposing the deposited sludge. Once the cesium is eluted in the
water, it can fix to a mineral such as zeolite. Now we need the properties of sludge in removal process by
decomposition system with circulation type. In this study, our objects is to check the characteristics of the
sludge particle in removal process of radioactive cesium from ocean sludge by decomposition system with
circulation type using micro bubbles and activating microorganisms. As the results of this experiments, we
had very good purification ratio on total nitrogen and had made 40 times of smaller size on diameter of the
particle of sludge.