Bioaugmentation of in-situ degradation of petroleum hydrocarbon from soil by indigenous microbial consortium

Removals of petroleum contaminants from soil is an environmental necessity due to the negative impacts on human and other living organisms. In environmental and economic aspects, biodegradation is the best treating methods for in-situ removal of hydrocarbons from contaminated soil. In this method, application of indigenous microorganisms could minimize perturbation of the soil ecosystem, and thus the treated soil could maintain biological activities for agriculture prepuces after the treatment. In this study, the potential of removal of crude oil contamination from soil by biodegradation process was evaluated in mud pit zones in Naft Shahr resource. In order to evaluate biostimulation, two treatments were applied; plowing alone and plowing together with 0.1 kg/m2 of urea as a source of nitrogen. In order to evaluate bioagumentation, in addition to plowing and adding urea, a suspension of native microbial consortium (consisting of Bacillus thuringiensis, Arthrobacter citreus, and Candida catenulata (a biosurfactant producer yeast)) was added to the soil in an amount of 100 mL/m2. The results indicated that the total petroleum hydrocarbon (TPH) removal was increased from 10.73% to 53.83% after 120 days by the biostimulation treatment. Also, bioagumentation could remove up to 74% of TPH at the same conditions. In this study, removals of main heavy hydrocarbons (> C12) and higher biodegradation rate were the advantages of bioagumentation process by the microbial consortium.