Evaluation of uranium-removal characteristics from soil-washed wastewater using precipitation methods

Maengkyo Oh^1*, Jun-Young Jung¹, Byung-Moon Jun³, Keunyoung Lee², Hee-Chul Eun¹

¹Radwaste Management Center, Korea Atomic Energy Research Institute (KAERI), 111 Daedeok-daero 989beon-gil, Yuseong-gu, Daejeon 34057, Republic of Korea
²Decommissioning Technology Division, Korea Atomic Energy Research Institute (KAERI), 111 Daedeok-daero 989beon-gil, Yuseong-gu, Daejeon 34057, Republic of Korea
³Department of Environmental Science and Engineering, Kyung Hee University, 1732 Deogyeong-Daero, Giheung-gu, Yongin-si, Gyeonggi-do 17104, Republic of Korea

Received 2025-01-24 ; Revised 2025-03-04 ; Approved 2025-03-17

Abstract

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–OHx) co-precipitation, uranium peroxide (UO₄) precipitation, and uranium phosphate (KUO2PO4) precipitation. The M–OHx 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–OHx and KUPO₄ 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–OHx 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.

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