Remediation of soil heavily polluted with polychlorinated biphenyls using a low-temperature plasma technique

Polychlorinated biphenyls (PCBs) were removed by low-temperature plasma technique (dielectric barrier discharge) from heavily polluted soil and their intermediate products were analyzed. The removal rate ranged from 40.1 to 84.6% by different treatments, and they were also influenced significantly (P < 0.01) by soil particle-size, electric power, gas flow rate and reaction time. The optimal reaction conditions of PCB removal from the soil were obtained experimentally when soil particle-size, electrical power, flow rate and reaction time were 5-10 mm, 21 w, 120 mL.min(-1) and 90 min, respectively. However, decreasing electrical power, flow rate and reaction time to 18 w, 60 mL.min(-1) and 60 min respectively were also acceptable in view of the cost of remediation. This technique was characterized by the additional advantage of thorough oxidation of PCBs in the soil, with no formation of intermediate products after reaction. The technique therefore shows some promise for application in the remediation of soils contaminated with persistent organic pollutants in brown field sites in urban areas.