Abstract: Chemical waste salt contains substantial insoluble substances (SS) and trace impurities such as calcium, magnesium, silicon, and TOC, which hinder its reutilization. In order to remove these impurities, this study investigated the removal efficiency of inorganic impurities through stepwise and synchronous removal methods, as well as the effectiveness of activated carbon adsorprion, resin adsorprion, heterogeneous ozone oxidation, and homogeneous ozone oxidation in TOC removal. Results demonstrate that synchronous impurity removal delivers superior inorganic impurity elimination. Under optimized conditions (pH 10.5, MgCl₂/SiO₂ molar ratio of 1.5, Na₂CO₃ excess dosage of 300 mg/L), effluent concentrations of SS, calcium, magnesium, and silicon can be reduced to 32, 0, 0.39, and 1.9 mg/L, respectively, with SS exhibiting synergistic removal effects on calcium, magnesium, and silicon. Compared to activated carbon adsorprion, resin adsorprion, and heterogeneous ozone oxidation processes, homogeneous ozone oxidation achieves a lower effluent TOC of 5.2 mg/L. The integrated "synchronous chemical precipitation + homogeneous ozone oxidation" process enables deep purification of micro-pollutants in chemical waste salt.

Key words: chemical waste salt, synchronous removal of impurities, calcium ion, magnesium ion, silicon dioxide, magnesium chloride, homogeneous ozone oxidation