물리화학적 처리를 이용한 군부대 사격장 내 중금속 오염 토양의 정화

Abstract

This study evaluated the feasibility of combined use of physical separation and soil washing to remediate heavy metals (Pband Cu) contaminated soil in a military shooting range. The soils were classified into two types based on the level ofheavy metal concentrations: a higher contaminated soil (HCS) with Pb and Cu concentrations of 6,243 mg/kg and 407 mg/kg, respectively, and a lower contaminated soil (LCS) with their concentrations of 1,658 mg/kg and 232 mg/kg. Pb level inboth soils exceeded the regulatory limit (700 mg/kg), and its concentration generally increased with decreasing soilparticle size. However, in some cases, Pb concentrations increased with increasing soil particle size, presumably due to thepresence of residues of bullets in the soil matrix. As a pretreatment step, a shaking table was used for physical separationof soil to remove bullet residues while fractionating the contaminated soils into different sizes. The most effectiveseparation and fractionation were achieved at vibration velocity of 296 rpm/min, the table slope of 7.0°, and the separatingwater flow rate of 23 L/min. The efficiency of ensuing soil washing process for LCS was maximized by using 0.5% HClwith the soil:washing solution mixing ratio of 1:3 for 1 hr treatment. On the contrary, HCS was most effectively remediatedby using 1.0% HCl with the same soil:solution mixing ratio for 3 hr. This work demonstrated that the combined use ofphysical separation and soil washing could be a viable option to remediate soils highly contaminated with heavy metals.