Biodegradation of Polycyclic Aromatic Hydrocarbons (PAHs) in Petroleum Contaminated Soils

Polycyclic aromatic hydrocarbons are a class of potentially hazardous chemicals of environmental and health concern. PAHs are one of the most prevalent groups of contaminants found in soil. Biodegradation of complex hydrocarbon usually requires the cooperation of more than single specie. In this research biotreatment of PAH (phenanthrene) was studied in a solid-phase reactor using indigenous bacteria isolated from two petroleum contaminated sites in Iran, (i.e., Tehran refinery site with clayey-sand soil composition and Bushehr oil zone with silty-sand soil composotion). Phenanthrene (C۱۴H۱۰) was made in three rates (۱۰۰, ۵۰۰, and ۱۰۰۰ mg/kg of soil) synthetically and was conducted with two bacterial mixed cultures for a period of ۲۰ weeks. Highest removal (more than ۸۵ %) of phenanthrene with rates of ۱۰۰, ۵۰۰ and ۱۰۰۰ mg/kg in clayey-sand soil with BMTRS (Bacterial Mix of Tehran Refinery Site) consortium was achieved within ۳, ۵ and ۱۴ weeks, respectively as for silty-sand soil composition with BMBOZ (Bacterial Mix of Bushehr Oil Zone) consortium was achieved within ۱۰, ۱۷, and ۱۹ weeks, respectively. Results for phenanthrene biotreatment in solid phase reactor revealed a significance relationship between concentration and type of microbial consortium with the removal efficiency of phenanthrene over the time (P value<۰.۰۰۱). Furthermore, there was a significant relationship between soil type with removal efficiency of phenanthrene over the time (P value=۰.۰۲۲). That means the bioremediation of the lower concentrations of phenanthrene needs shorter time compared with the higher concentrations.  Microbial analysis using confirmative series tests and analytical profile index (API) kit tests showed the Pseudomonas fluorescence, Serratia liquefaciens, Bacillus and Micrococcus strains as dominant bacteria in the mixed cultures.

کلیدواژه ها:

Polycyclic Aromatic Hydrocarbons (PAHs) ، Bioremediation ، PAH-degrading microorganisms ، PAH contaminated soils