BIOREMEDIATION OF A POLYCYCLIC AROMATIC HYDROCARBON-CONTAMINATED SOILBY USING DIFFERENT AEROBIC BATCH BIOREACTOR SYSTEMS

The intrinsic depuration capability of a soil contaminated by polycycl ic aromatic hydrocarbons (PAHs) originating from a contaminated indust rial site was evaluated in this study by using different aerobic batch bioreactors: a slurry-phase bioreactor, a blade-agitated bioreactor, and a rotary vessel bioreactor. For each bioreactor, the disappearance of 14 target PAHs and of the total extractable organic matter was mon itored. The three treatments exhibited rapid and extensive removal of the PAHs, which disappeared at different degradation rates according t o their molecular weight and aromaticity degree. PAHs with two, three and four aromatic rings were degraded in sequence, with average rates that generally decreased as the number of molecule rings increased. A slight increase in the bacterial biomass concentration and significant CO2 production were also observed during the time course of the treat ments. Among the three treatments, the slurry-phase system provides th e most effective and fastest removal of the PAHs and the organic extra ctable matter. However, the semisolid-phase systems exhibited PAH depl etion capabilities higher than those reported in the literature for sa ils with similar particle size distribution in solid-phase conditions.