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

Abstract

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.