Effect of ozonation on polychlorinated biphenyl degradation and on soil physico-chemical properties

The objectives of this study were to investigate the effectiveness of ozone treatment on degradation of polychlorinated biphenyl (PCB) contaminated soils and to observe the subsequent changes in soil physico-chemical properties. Furthermore, the ability of plants to grow on the ozone-treated soils was evaluated. Soils with different physico-chemical characteristics spiked with seven PCB congeners in two different time periods were chosen. Ozonation was more efficient for PCB degradation in freshly spiked soils and the removal efficiency increased with increasing ozonation time. The highest decrease was found in the soil with a lower soil organic matter (SOM) content and a coarser soil structure indicating the substantial effect of soil characteristics on the efficiency of ozonation. The composition of individual PCB congeners changed in all treatments in terms of higher accumulation rate of highly chlorinated biphenyls with a higher ozonation time. Increased mobility of several elements, changes in SOM content and in soil pH were detected after ozonation. Vulnerability of plants to these modifications was documented on rape seedlings. No inhibition in growth during any treatment and predominantly higher concentration of PCB in non-ozonated treatments were observed. Results suggest that this method can present a promising environmental friendly remediation technology for PCB contaminated soils.