Bioventing of hydrocarbon ‐ contaminated soil and biofiltration of the off ‐ gas: Results of a field scaleinvestigation

Abstract

Bioremediation through venting, biodegradation and biofiltration was considered to be a feasible approach to remediate a hydrocarbon‐contaminated soil from a site underneath a paint factory. Before the field‐scale treatment process was designed, a microbial enumeration study was performed to estabilish the existence of an indigenous population of microorganisms capable of degrading naphtha in the impacted soil. A significant remediation of a limited area contaminated with approximately 100 Kg of naphtha, toluene and xylenes was achieved in a 2 month treatment in which the soil was remediated to conform with local soil quality regulations. The bulk of soil removal of contaminants was achieved by vapour extraction (about 70 kg). Biodegradation also provided a significant contaminant removal (about 18 Kg). The hydrocarbons removed from the vent system were successfully biofiltered and outlet gas stream concentrations were acceptable under Italian national law. The biodegradative capacity of a mixed culture of microorganisms selectively isolated from the soil was tested in vial culture experiments. After 1 day of incubation, four of the seven most important naphtha components were completely degraded; the remaining constituents were slowly degraded.