Simultaneous removal of suspended fine soil particles, strontium and cesium from soil washing effluent using inorganic flocculants

The purpose of this study was to remove suspended soil, Sr2+, and Cs+ that may exist in soil-washing effluents using an inorganic coagulant (J-AF). The major chemical constituents of the flocculant J-AF were SO3 and CaO, and were confirmed to have thenardite (Na2SO4), calcium carbonate (CaCO3), and tychite (Na6Mg2(CO3)4(SO4)) crystals. When 10 g/L of J-AF was injected into the turbid solution containing unstably suspended soil particles of <45μm, the suspended soil could be completely precipitated. The agglomerates of suspended soil formed using J-AF had a maximum size of more than 1 mm, due to which sedimentation was effective. The precipitation of suspended soil by J-AF was more favorable under acidic conditions, such as pH 2, 3, and 5. Sr2+ was mainly removed from the supernatant by adsorption using J-AF, and Cs+ was precipitated by J-AF while adsorbed on suspended soil and subsequently eliminated from the supernatant. These results provide that J-AF can be used for the simultaneous removal of suspended soil, Sr2+, and Cs+ from a radioactive soil suspension.