Coupling of bioaugmentation and phytoremediation to improve PCBs removal from a transformer oil-contaminated soil

This study was carried out to assess the dissipation of 17 selected polychlorinated biphenyl (PCBi) congeners in a transformer oil-contaminated soil using bioaugmentation with 2 PCB-degrading bacterial strains, i.e., Pseudomonas spp. S5 and Alcaligenes faecalis, assisted or not by the maize (Zea mays L.) plantation. After 5 and 10 weeks of treatment, the remaining concentrations of the target PCBi, congeners in the soil were extracted and measured using GC-MS. Results showed that the bacterial augmentation treatments with Pseudomonas spp. 55 and A. faecalis led to 21.4% and 20.4% reduction in the total concentration of the target PCBs (Sigma PCBi), respectively, compared to non-bioaugmented unplanted control soil. The Sigma PCBi, decreased by 35.8% in the non-bioaugmented planted soil compared with the control. The greatest degradation of the PCB congeners was observed over a 10-week period in the soil inoculated with Pseudomonas spp. S5 and cultivated with maize. Under this treatment, the Sigma PCBi, decreased from 357 to 119 ng g(-1) (66.7% lower) and from 1091 to 520 ng g(-1) (52.3% lower). Overall, the results suggested that the combined application of phytoremediation and bioaugmentation was an effective technique to remove PCBs and remediate transformer oil-contaminated soils.