Bench-scale soil washing experiments were conducted to remove fluoride from contaminated soils. Five washing solutions including hydrochloric acid (HCl), nitric acid (HNO3), sodium hydroxide (NaOH), sulfuric acid (H2SO4) and tartaric acid (C4H6O6) were tested. The concentration of the washing solutions used ranged from 0.1 to 3 M with a liquid to solid ratio of 10. The soil washing results showed that the most effective washing solution for the removal of fluoride from contaminated soils was HCl. The highest fluoride removal results of approximately 97 % from the contaminated soil were obtained using 3 M HCl. The fluoride removal efficiency of the washing solution increases in the following order: C4H6O6 < NaOH < H2SO4 < HNO3 < HCl.

Bench-scale soil washing experiments were conducted to remove both heavy metals (Pb, Cu, Zn) and petroleum from contaminated soils. Diverse washing solutions including hydrochloric acid (HCl), nitric acid (HNO3), sulfuric acid (H2SO4), tartaric acid (C4H6O6) and ethylenediaminetetraacetic acid (C10H16N2O8, EDTA) were used. The concentration of the washing solutions used in this study ranged from 0.1 M to 3 M with a liquid to solid ratio of 10. The soil washing results showed that hydrochloric acid (HCl) was the best washing solution at 3M for heavy metals removal. Other washing solutions also showed a significant removal of heavy metals, except for sulfuric acid (H2SO4). Sulfuric acid (H2SO4) had the worst performance of all the washing solutions with respect to removing Pb. 1M HCl and HNO3 were sufficient for effective Pb and Cu removal and all of the tested washing solutions at a concentration of 0.1 M were able to pass the Korean warning standard for Zn removal. In the case of TPH removal, tartaric acid (C4H6O6) was the best washing solution for the removal of TPH from contaminated soil. Overall, tartaric acid (C4H6O6) could be a viable washing solution for the removal of both heavy metals (Pb, Cu, Zn) and TPH from contaminated soils.