Remediation of Diesel Contaminated Soils Using Surfactants: Coulumn Study

Abstract

This study presents the experimental remediation studies of diesel contaminated soil with Sodium Deducible Sulfate (SDS) as surfactants using column tests. Sandy selected soil had the grain size distribution of # 40 meshes to the # 200 mesh range. The soil columns were contaminated with adequate diesel amount to achieve the concentration of 10000 and 20000 ppm in soil. 0.1, 0.2, 0.3, 0.4 percent of surfactants and pH values of 4, 7, 9 and 11, were examined. After 72 h, washing began and all tests were continued up to 10 pore volume and the trend of remediation and permeability of soil during the test was investigated. pH and TPH of outlet solution measured during 2, 4, 6 and 10 pore volumes. Times were recorded during 0.67, 1, 1.33, 2, 3.33, 4, 5.67, 6, 7.33, 8, 8.67, 9.33 and 10 pore volumes, in order to calculate permeability values.Results showed that in all states the quantity of remediation for acidic states was very low and efficiency of remediation when using only water was about (1:3) of maximum amount. For soil with initial contaminant concentration of 10000 ppm the maximum efficiency is for surfactant in the concentration of 0.3 and pH = 11 and for soil with initial contamination amount of 20000 ppm the maximum efficiency is for surfactant in the concentration of 0.1 and pH = 11. By increasing the amount of surfactant concentration, the permeability of soil decreased and in pH = 11 the amount of permeability is maximum. With increasing initial contamination quantity rate of increasing of remediation and permeability decreased. Consequently in the low level of contamination the effect of washing solution pH value in soil remediation and permeability is more in comparing with high level of contamination. For initial contamination of 10000 ppm optimum removal efficiency obtained 35% for surfactant of 0.3% and pH = 11. For initial contamination of 20000 ppm, optimum removal efficiency is obtained as 45% for 0.1% of surfactant and pH = 11. Using of higher soil column, sampling from different elevation for investigating remediation trend in height and surveying temperature effect on diesel contaminated soil remediation can help to modification procedure and improvement of efficiency.