Organic solvents improve hydrocarbon desorption and biodegradation in highly contaminated weathered soils

Abstract

Slurry phase laboratory microcosms were used to investigate the effect of selected solvents (hexane, benzene, toluene, n-butanol, acetone, and methanol) on desorption and the resulting microbial biodegradation of hydrocarbons in highly contaminated weathered soils. For nonpolar solvents, solubility and desorption of hydrocarbons increased linearly as polarity increased. In desorption and biodegradation assays, toluene significantly increased hydrocarbon consumption by twice as much, in comparison to the control without solvent. After 30 culture days, the initial hydrocarbon concentration in soil (Soxhlet method), 237.2 g kg –1 of dry soil, diminished 21% when toluene was initially added. Saturated and aromatic fractions became degraded to a greater extent in the presence of toluene, 11% and 50%, respectively. The results in this research indicated that the use of solvents is effective in improving both hydrocarbons desorption and biodegradation in highly polluted weathered soils. Key words: slurry phase, overall hydrocarbon biodegradation, solvents, hydrocarbon fractions, biodegradation.