Development, assessment and evaluation of a biopile for hydrocarbons soil remediation

• The biopile under study proved effective for hydrocarbons removal.
• The commercial inoculant used did not colonize the long time polluted soil.
• The inoculant was effective on a recently polluted soil.
• Microbial diversity appears to be low in polluted soil as shown by Amplified ribosomal DNA restriction analysis (ARDRA).
• Microbial analysis indicated correlation between metabolic activity and bioremediation.

Soil at a site located in North-Eastern Italy has been impacted by a persistent, long term exposure to diesel fuel. The concentration of organic contaminants in soil exceeded the acceptable limits indicated by the present regulations concerning the specific use-destination of the sites and its reclamation. The contamination involved several thousands square meters of soil surface resulting in some thousand cubic meters of soil. Approximately 650 cubic meter of the most contaminated soil was moved to a nearby site where a biopile was assessed with the aim to enhance the activities of the soil community to reduce the oil concentration. In order to verify the correct operation of the system it was continuously monitored in terms of chemical concentration, biological activity and community structure. The main remediation occurred within the first 300 days of treatment allowing the soil to be back within the threshold defined by current laws for industrial and commercial activities. An additional 200 days treatment was needed to further reduce the oil content to the limits required for public parks and residential areas. Lab scale biopiles were also assessed to evaluate the role of commercial inoculants in the remediation process.