Capacity of Phytoremediation, Bioremediation and Their Combined Application to Remove Petroleum Pollution from Soil

Petroleum hydrocarbons have become a global problem for the environment. These compounds are highly resistant to the environment and are harmful to human health. The purpose of this experiment was to Comparison of phytoremediation, bioremediation and bioaugmented phytoremediation efficiency to remove crude oil from soil. For this purpose, a factorial experiment was conducted in a completely randomized design with three replications. The treatments consisted of 3 levels of soil pollution to oil (0, 4 and 8% oil), 4 treatments of plant (no plant, bermudagrass, sorghum and barely) and 3 treatments of bacteria (no bacteria, Psudomonas putida and Azosprillum brasilense). Soils were polluted with different amounts of crude oil and after 6 weeks, soils were inoculated with Pseudomonas putida and Azospirillium brasilense bacteria, then three gramineae species were planted. Ninty days after planting, plants were harvested.The results showed that removal percentage of crude oil by phytoremediation alone, bioremediation alone and combined application of plant and bacteria significantly increased compared to control. Plants were more effective than bacteria in removal oil pollution and plant increased bacteria function significantly so that, there were significant difference among treatments of plant, bacteria and plant+ bacteria. The highest removal percentage was observed in combined application of plant and bacteria [1]. At all treatments of soil inoculation with bacteria, with increasing levels of oil pollution, dry weight of plants decreased but, at each level of crude oil pollution, inoculation of soil with bacteria, the dry weight of shoot increased. Incubated soil with bacteria improved dry weight of shoot through removal of oil pollution in soil [2]. With increasing level of crude oil pollution, activities of arylsulfatase and dehydrogenase in soil increased compared to control significantly. However at the highest level of crude oil (8%), activities of these enzymes in soil decreased compare to 4% crude oil. Activity of these enzymes in soil were significantly increased by incubation of soil with bacteria alone, plant cultivation alone and combined application of plant and bacteria compared to control [3]. The highest activity of enzymes in the treatment of 4% crude oil pollution and inoculation with Pseudomonas putida and planting sorghum were measured. Establishment of plant with microorganisms can be considered as a key component of the strategy to remove hydrocarbons. Consequently, these bacterial and plant species can be used for the biodegradation of soils contaminated with crude oil.