Bioremediation of diethylhexyl phthalate contaminated soil: a feasibility study in slurry- and solid-phase reactors

The aim of the research was to verify the possibility of applying bioremediation as a treatment strategy on a poly(vinyl chloride) (PVC) manufacturing site in the north of Italy contaminated by diethylhexyl phthalate (DEHP) at a concentration of 5.51 mg/g of dry soil. Biodegradation kinetic experiments with DEHP contaminated soil samples were performed in both slurry- and solid-phase systems. The slurry-phase results showed that the cultural conditions, such as N and P concentrations and the addition of a selected DEHP degrading strain, increased the natural DEHP degradation rate. On the basis of these data, experiments to simulate bioventing on contaminated soil columns were performed. The DEHP concentration reached 0.63 mg/g of dry soil in 76 days (89% of degradation). A kinetic equation was developed to fit the experimental data and to predict the concentration of contaminant after treatment. The data obtained are encouraging for a future in situ application of the bioventing technology.