Phytoremediation is the use of plants and their associated microorganisms for the in situ (or on-site) treatment of contaminated soils. Based on a review of relevant literature, we have concluded that phytoremediation is a steadily emerging technology with the potential to facilitate the cleanup of petroleum hydrocarbons at oil-contaminated sites. Initial indications are that phytoremediation is effective at degrading and containing
petroleum hydrocarbons in soil as well as transferring these compounds from soil to the atmosphere. The literature suggests that the degradation of petroleum hydrocarbons by microorganisms in the rhizosphere of plants is the primary loss mechanism for these compounds.
The three major alternatives to phytoremediation are natural attenuation, engineering, and bioremediation. Limited information suggests that phytoremediation is slightly less expensive than bioremediation and can be orders of magnitude less expensive than some of the more costly engineering techniques. It is faster than natural attenuation, but typically slower than engineering and bioremediation. Because phytoremediation is an in situ technique, it is less disruptive compared to the excavation efforts required in ex situ engineering and bioremediation. Phytoremediation is most likely to have the greatest effectiveness with shallow contamination, which is co-incidental with the greatest root density.