REMEDIATION OF A FORMER TANKS AREA THROUGH THE BIOPILE TECHNIQUE

摘要

In the context of a project to requalify dismissed industrial sites in the Venice area, an extensive site assessment was carried out in 1998 on an 11-hectare area formerly occupied by an oil tank farm. The characterization of the area included a detailed assessment of hydrogeological, chemical-physical, and microbiological characteristics of soil and groundwater. Together with field activities, a laboratory study was conducted to verify the possibility of utilizing bioremediation techniques to restore hydrocarbon-contaminated soils. Due to the peculiar geology of the site, and the encouraging results of the biodegradation simulation tests, the selected technique was the use of biopiles for on-site treatment of contaminated soils. Design and management of a pilot-scale biopile completed the data required for the design of the full-scale remediation of the area. In the future, a total of 54,000 tons of soil with Total Petroleum Hydrocarbons (TPH) concentrations as high as 12,000 mg/kg (average TPH concentration 3,000 mg/kg) will be biotreated in batches of four biopiles for a total of nine, having the capacity of 6,000 tons each and dimensions of 110 m x 20 m. The enhancement of microbial degradation is obtained by oxygenating the soil, previously pretreated and mixed with perlite and nutrients. The process is monitored over time by evaluating different chemical and physical parameters such as temperature, oxygen and water content, nutrient consumption, contaminant degradation, and microbial flora. Up to now, the soil present in the first batch of four biopiles has been completely treated. Of particular interest is the degradation trend of the PAH fraction together with the disappearance of different heavy and light hydrocarbon fractions, according to the Italian regulatory standards.