PILOT SCALE TEST FOR THE STABILIZATION PROCESS BY USING LIMESTONE AND STEEL MAKING SLAG IN ZN, PB AND CU CONTAMINATED FARMLAND SOIL IN KOREA

Field experiment of the stabilization process using limestone and steel making slag was performed for Cu, Zn and Pb contaminated farmland soil around abandoned mine, Korea. For the pilot scale test, total 4 testing grounds (each of 2 m x 2 m x 0.5 m) were installed in the site. As the amendment, limestone 1 %, limestone 2 % + steel making slag 1 %, limestone 3 % + steel making slag 2 % were added into the soil of the testing ground, respectively. For each testing ground, two PVC pipes (1cm in diameter) were installed in 30 cm and 50 cm deep and the periodic monitoring was carried out to measure heavy metal concentration for 3 months. After 2 weeks of stabilization, young rice plants were planted at each testing ground and the influence of the amendments on heavy metal transfer to the rice plant was investigated by measuring heavy metal concentrations of plants. From results of monitoring, the heavy metal leaching from soils in testing grounds decreased with the amendment. The background testing ground (without amendment) maintained 10 mg/L of Zn concentration in leached solution from 30 cm deep pipe and 20 mg/L from 50 cm deep pipe. However, by adding amendments into the testing ground, Zn concentration continuously decreased to less than 1 mg/L. Rice plants were sampled from the testing ground and were divided into roots, leaves (including stem) and grains and their heavy metal concentrations were analysed. Heavy metal transfer from the soil to roots was the highest and the lowest to rice grains. At all of plant samples, Cu, Pb and Zn transfer to the plant decreased by 48 ~ 82 % when the amendment was added. In particular, the greatest drop of heavy metal transfer to rice plants in the testing ground occurred by adding limestone 3 % and steel making slag 2 %. Results of this study indicated that the use of mixed limestone and steel making slag decrease not only leaching of Cu, Pb and Zn from soil but also transfer to plant.