Design and applicability of a water recycling system to treat wastewater generated from real uranium-contaminated soil

This study investigated, from practical and engineering perspectives, a systematic design and its ability to remediate real U-contaminated soil, with the aim of assessing the performance of a zero liquid discharge system for treating wastewater from a soil-washing process. Specifically, we carried out a purification process for U-contaminated soil and its wastewater; the proposed method consisted of U(VI) precipitation, solid–liquid separation with a filter-press, and distillation of the filtrate on the basis of U(VI) concentration. Experimental results indicated complete separation of uranium from the contaminated soil. Self-disposal of the treated soil was possible because it contained uranium at a concentration less than 1.0 Bq·g⁻¹, which the International Atomic Energy Agency has suggested as the clearance level for radionuclides. In terms of the zero liquid discharge system, the distillation process enabled not only water reuse of the filtrate after solid–liquid separation but also self-disposal of high-purity Na₂SO₄ in the residues of the distilled filtrate. According to a comparison of the economic analysis between direct disposal and the application of a remediation process to treat U-contaminated soil, the proposed comprehensive zero liquid discharge system for the treatment of U-contaminated soil is a practical and feasible option. We anticipate that the valuable experimental results and implications in this study will play a significant role in both academia and industry given the demonstration of design and applicability of the proposed zero liquid discharge system to treat wastewater generated from real U-contaminated soil.