Degradation of polycyclic aromatic hydrocarbons in soil: the Fenton reagent versus ozonation.

The ozonation and the Fenton treatment of soil spiked with a mixture of eleven polycyclic aromatic hydrocarbons (PAH) were studied. The efficiency of the treatment was strongly dependent on the matrix of soil (sand or peat). PAH adsorbed on sand undergo degradation more easily and require less oxidants (ozone, hydrogen peroxide) than PAH adsorbed on peat. Soil ozonation and the Fenton treatment were effective not only for the removal of 3-ring PAH, but could effectively degrade also 4-, 5- and more ring PAH. PAH removal from soil with the Fenton treatment in slurry was found to be dependent on the ratio of H2O2/soil/Fe2+, the manner of addition of hydrogen peroxide, and the treatment time. Three-phase ozonation of PAH contaminated soil resulted in a lower PAH removal and required higher ozone doses than two-phase ozonation. An improvement of the biodegradability during the chemical oxidation favours the implementation of combined chemical treatment and biodegradation for remediation of PAH contaminated soil.