ALCOHOL FLUSHING FOR ENHANCED REMOVAL OF COAL-TAR FROM CONTAMINATED SOILS

Alcohol flushing for enhancing the removal of coal tar from contaminat ed soils and reducing coal tar concentrations in the aqueous-phase lea chate was investigated. Four soil columns were packed with relatively undisturbed coal tar contaminated soils collected from a former coal g asification site. These columns were leached with water and then flush ed with isopropyl alcohol (IPA) solutions. Initially, total coal tar c oncentrations in water leachate ranged from similar to 0.1 to 150 mg/L for the four columns. Coal tar concentrations in the column effluent generally increased three to five orders of magnitude during the initi al IPA flush. Each column was flushed with 1-3 pore volumes of an IPA solution. Reduction of coal tar concentrations in water leachate, attr ibuted to the alcohol flushing, was noted in three of the four columns . The total coal tar removed from the soil columns during the IPA flus hes constituted from 54 to 97% of the total coal tar removed during bo th water leaching (240-800 pore volumes) and alcohol flushing(1-3 pore volumes). The alcohol hushing removed from 3 to 19% of the total coal tar in the various soil columns. Results indicate that alcohol flushi ng can enhance the removal of coal tar from contaminated soils and can reduce the aqueous-phase coal tar concentrations in leachate.