Remediation of actual U(VI)-contaminated soil for self-disposal via recycling processes of low concentrated acidic wastewater

This study presents a comprehensive remediation strategy for U(VI)-contaminated soil that facilitates self-disposal by recycling of mild acidic wastewater, specifically H₂SO₄ concentrations ranging from 0.05 to 0.1 M. The primary objective is to evaluate the impact of recycling acidic wastewater up to four times on achieving the desired clearance levels. The results indicated that decontamination efficiency was largely proportional to H₂SO₄ concentration, demonstrating that milder soil-washing conditions with multiple washing steps effectively remediated U(VI)-contaminated soil. Additionally, pH monitoring showed that pH trends could serve as a critical indicator for determining the completion of soil washing, reflecting the dissolution of oxides in soil through reactions between oxide surfaces and H⁺ ions. In summary, wastewater recycling resulted in a 63% reduction in the use of concentrated H₂SO₄ compared to non-recycling processes, providing substantial evidence for the efficacy of wastewater recycling. An economic analysis comparison suggests that the proposed total system is a practical solution for remediation of U(VI)-contaminated soil due to the recovery of high-purity U precipitate, which enhances overall cost efficiency from an economic perspective.