In this study, the removal of 17 selected PCB i congeners was assessed in a transformer oil contaminated soil using bioaugmentation with two PCB-degrading bacterial strains, i.e. Pseudomonas sp. S5 and Alcaligenes faecalis , assisted or not by maize ( Zea mays L.) and Alternanthra ( Alternanthra sessilis ) plantation. Also bentonite powder was applied to the soil at different rates. Treatments were arranged in a factorial manner in a completely randomized design with three replicates. Plants were harvested after 35 and 70 days for maize, 90 and 180 days for alternanthra. Bioaugmentaion by Pseudomonas sp. S5 and Alcaligenes faecalis was positive and significant effect on PCBs degradation. Moreover, addition of bentonite significantly (P 0.05) enhanced the plant growth and dissipation of the residual soil PCBs congeners under planting maize and alternanthra. Simultaneous application of phytoremediation, bioaugmentation and bentonite addition on PCBs significantly increased the PCBs removal from the contaminated soil. Analysis of the aerial part of the maize and alternanthra plants showed no detectable PCBs congeners, hence the vital role of the plants in PCB removal from the soil was mainly due to rhizostimulation, not phtoextraction. The result suggested that coupling of phytoremediation and bentonite addition is an effective technique to remove PCBs and remediate transformer oil- contaminated soils. Key words: polychlorinated biphenyls; hydrocarbo soil contamination; bioremediation
