Some Investigation on Bioremediation of PahsContaminated Soil in Iran Tar Refinery

The main purpose of this research is studying the possibility of bioremediation of polycyclic aromatic hydrocarbons (PAHs) contaminated soils in Iran’s tar refinery area located in Isfahan. For many years a great quantity of tar produced by neighboring metallurgical plant has been stored in lagoons as natural reservoirs, causing the contamination of soil in this area. Microorganisms capable of transforming PAHs, such as anthracene and phenanthrene, are commonly found in soil, especially soil previously contaminated with PAHs and microorganisms capable of transforming PAH compounds have been used to decontaminate soil. In the first phase of our study, we focused on isolation and purification of PAHs utilizing microorganisms from soil. The results of site characterization and biofeasibility testing have shown the presence of a viable native population of community of specific contaminant-degrading microbes already in the site. Therefore, biostimulation becomes an available option. It is the essence of this option that the native (indigenous) microbial community is found to be capable of degrading the target site contaminants (PAHs) if managed properly. In this research for the first time in Iran we have studied, the possibility of bioremediation of PAHS contaminated sites by indigenous microorganisms. Microbiological analysis of soil chronically exposed to coal tar of an industrialized area near the city of Isfahan, resulted in the isolation of some bacteria which degraded, each of, naphthalene, phenanthrene, and, anthracene in an aqueous solution, when grown for two weeks in pure culture with organic nutrients. The initial PAH concentration was at the water solubility level and degradation proceeded to no detectable level, in some cases. They grew well at 25°C to 30°C. The use of these microorganisms may be an attractive alternative to existing physiochemical method for the remediation of PAH in the environment.