The synergistic effect of oil-degrading bacteria Bacillus megaterium and Bacillus subtilis on phytoremediation of oil-contaminated soils by Agropyron cristatum and Achillea millefolium, Case study: Soils around Ray refinery in Tehran

The objective of the present research is to assess the application of petroleum-degrading bacteria and the phytoremediation of petroleum-contaminated soils in a greenhouse experiment. For this purpose, rangeland species Agropyron cristatum and Achillea millefolium in treatments with and without inoculation with petroleum-degrading bacteria Bacillus megaterium and Bacillus subtilis for petroleum contaminated soil surrounding Tehran refinery with pollution ۵.۳ and ۷ wt% were used. Another objective of this research is to monitor the TPH changes in the greenhouse condition with and without inoculation of bacteria for Agropyron cristatum and Achillea millefolium. The results indicated the best TPHs removal efficiency for Agropyron cristatum at the end of the growth period in the presence of Bacillus megaterium and Bacillus subtilis treatment which in ۵.۳ wt% contamination level, it was ۷۲.۱۸ and ۶۴.۰۸% respectively and as for Achillea millefolium it was ۶۰.۵۹ and ۵۸.۱۲% respectively. Also, the percentage of EC reduction in Agropyron cristatum at the end of the growth period in the presence of Bacillus megaterium and Bacillus subtilis treatment at ۵.۳ wt% contamination level was ۴۲.۳۷% and ۳۹.۲۷% respectively and as for Achillea millefolium it was ۳۳.۴۱ and ۳۱.۴۸% respectively. In the presence of bacteria, the highest pH reductions were recorded in Bacillus subtilis treatment for Agropyron cristatum with about ۷.۲۵%. Finally, it can be noted that Agropyron cristatum and Achillea millefolium cultivated in TPH-contaminated soil are resistant to oil contamination and reduce some oil contamination, however, Agropyron cristatum was superior in removing petroleum contaminants.

کلیدواژه ها:

petroleum-degrading bacteria ، rangeland species ، Tehran oil refinery ، TPH