Journal of Nuclear Fuel Cycle and Waste Technology

Uranium-contaminated soil can be effectively decontaminated through acid leaching; however, this process process generates significant amounts of radioactive wastewater. Therefore, developing efficient methods to remove uranium from wastewater is essential to minimize radioactive waste generation. This study investigates the applicability of various precipitation methods for uranium removal from acidic wastewater produced during soil-washing processes. Three methods were evaluated: metal hydroxide (M–OH_x) co-precipitation, uranium peroxide (UO₄) precipitation, and uranium phosphate (KUO₂PO₄) precipitation. The M–OH_x precipitation method removes uranium by precipitating excess metal ions in wastewater by adjusting the pH. This method is easy to use and has a high removal efficiency. The UO₄ and KUO₂PO₄ precipitation methods involve adding reagents to precipitate uranium in the mineral phase. They enable selective uranium separation and further volume reduction. In the results, M–OH_x and KUO₂PO₄ precipitation methods remove uranium to less than 1 mg∙L⁻¹ within 2 h, demonstrating superior capabilities compared to UO₄ precipitation. The optimal method is different depended on the management strategy for the recovered uranium. The M–OH_x precipitation method was suitable for permanent disposal, whereas KUO₂PO₄ could be recycled. Based on these findings, guidelines for the effective treatment of wastewater containing uranium from the soil-washing process can be established.

Keywords

Soil washing, Wastewater treatment, Uranium precipitation, Studtite, Meta-ankoleite, Metal hydroxide co-precipitation