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

Abstract

The purpose of this study was to remove suspended soil, Sr 2 + , 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 SO 3 and CaO, and were confirmed to have thenardite (Na 2 SO 4 ), calcium carbonate (CaCO 3 ), and tychite (Na 6 Mg 2 (CO 3 ) 4 (SO 4 )) crystals. When 10 g/L of J-AF was injected into the turbid solution containing unstably suspended soil particles of < 45 μ m , 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. Sr 2 + 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, Sr 2 + , and Cs + from a radioactive soil suspension. • J-AF successfully flocculated and precipitated suspended soil. • Suspended soil precipitated favorably at pH 2, 3, and 5. • Sr 2+ was adsorbed by soil and J-AF, and was partially co-precipitated. • Cs + precipitated while adsorbed onto the soil and separated from the aqueous phase.