Phytoremediation of Contaminated Soils to Sludge of Oil Reservoirs using Prosopis juliflora (Sw.) DC.

Oil contaminated soil is a vital threat to the environment. The aim of the present research was to investigate the total petroleum hydrocarbon (TPH), and heavy metals of nickel and vanadium reduction using Prosopis juliflora, under different treatments of biochar and compost in pots. One-year-old P. juliflora seedlings were planted in pots containing oil sludge. The pots included 1 and 2% of compost and biochar. Furthermore, two control treatments including with and without P. juliflora were used for the study. This study was conducted in the complete randomized plot sampling with three replications. After six months, soil samples were taken from the pots and transferred to the laboratory. Then, the concentration of TPH, nickel, and vanadium was determined. The results indicated that the least TPH belonged to the compost 2% treatment (10.63 ppm), which was significantly different compared with other studied treatments. The highest value belonged to the control treatment without P. juliflora (22.57 ppm). The highest value of vanadium belonged to the control treatment (69.50 mg/kg). Compost 2% had the least values of vanadium (47.66 mg/kg). Comparison between treatments showed no significant differences among compost 1% (117.17 mg/kg), compost 2% (118.00 mg/kg), and biochar 2% (116.67 mg/kg). The highest reduction of nickel was observed within the mentioned treatments. Therefore, using biochar and compost can improve the phytoremediation capacity of P. juliflora.