Optimization of petroleum hydrocarbon biodegradation by indigenous and non indigenous microorganisms

Obtaining oil per day in Iran often caused its distribution and emission to the environment in various stages of operation and transportation. Efficient methods to clean up soil pollution, but environmentally friendly and suitable is inevitable. The aim of this study was optimization of total petroleum hydrocarbons (TPH) biodegradation by indigenous and non indigenous microorganisms in different applied remediation methods. Then, the best performance and trend of hydrocarbon contamination decomposition in time series were determined. Hence Ray's refinery contaminated soil with 38% TPH was used and thirteen treatments including fertilizers, animal manure, sawdust and inoculation of bacteria's (Bacillus subtilis, Bacillusmegaterium, Pseudomonasputida) were applied in soil thirteen times (every 2 weeks). The results showed that, treatments of bacteria + sawdust and bacteria had the greatest impact respectively with 35% and 34% decrease, of oil pollution of this soil and treatment of dry soil (without any additives except aeration) with a 20% reduction, had less effective in the amount of oil, than other treatments. The results indicated that, by active indigenous microorganisms and improving environmental conditions including aeration, additional nutrients and moisture, decomposition rate of petroleum can be increased. If native microorganism activity has low level, mixing sawdust, animal manure with inoculated non-native microorganisms including oil-eating active bacteria, will increase the process of reducing petroleum pollution.