Abstract
The use of plants to remove Poly-aromatic-hydrocarbons (PAHs) from soil (phytoremediation) is emerging as a cost-effective method. Phytoremediation of contaminated soils can be promoted by the use of adding microorganisms with the potential of pollution biodegradation (bioaugmentation). In the present work, the effect of bacterial consortium was studied on the capability of Sorghum and Onobrychis sativa for the phytoremediation of soils contaminated with phenanthrene and pyrene. 1.5 kg of the contaminated soil in the ratio of 100 and 300 mg phenanthrene and/or pyrene per kg of dry soil was then transferred into each pot (nine modes). The removal efficiency of natural, phytoremediation and bioaugmentation, separately and combined, were evaluated. The samples were kept under field conditions, and the remaining concentrations of pyrene and phenanthrene were determined after 120 days. The rhizosphere as well as the microbial population of the soil was also determined. Results indicated that both plants were able to significantly remove pyrene and phenanthrene from the contaminated soil samples. Phytoremediation alone had the removal efficiency of about 63% and 74.5% for pyrene and phenanthrene respectively. In the combined mode, the removal efficiency dramatically increased, leading to pyrene and phenanthrene removal efficiencies of 74.1% and 85.02% for Onobrychis sativa and 73.84% and 85.2% for sorghum, respectively. According to the results from the present work, it can be concluded that Onobrychis sativa and sorghum are both efficient in removing pyrene and phenanthrene from contamination and bioaugmentation can significantly enhance the phytoremediation of soils contaminated with pyrene and phenanthrene by 22% and 16% respectively.
Highlights
Polycyclic Aromatic Hydrocarbons (PAHs) are a group of persistent organic pollutants with two or more benzene rings
The collected soil samples did not have prior contamination, a rather significant level of degradation was achieved in the natural treatment for both pyrene and phenanthrene
The results from the present work suggested that the application of Onobrychis sativa and Sorghum can enhance the removal of phenanthrene and pyrene from the soil
Summary
Polycyclic Aromatic Hydrocarbons (PAHs) are a group of persistent organic pollutants with two or more benzene rings. These compounds are mainly produced via incomplete combustion or pyrolysis of organic compounds [1]. PAHs are hydrophobic compounds that are quickly adsorbed by particulate materials. They are abundant in soil [2]. A number of PAHs are known to have mutagenic, carcinogenic, and teratogenic effects [3]. A broad range of physical, chemical, and biological methods have been applied for the remediation of water and soil contaminated with these hydrophobic organic compounds [4,5,6]
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