Background & Objective: Aromatic hydrocarbons are produced by incomplete combustion of fossil fuels and pollute the soil following the emission into the atmosphere by precipitation. Numerous studies suggest that microbial inoculation has contributed to biodegradation of aromatic hydrocarbons. However, other studies have not confirmed the efficacy of this procedure in biodegradation. Regarding the contradictory findings, this study was conducted to evaluate capability of microorganisms isolated from oil-polluted soils in biodegrading aromatic hydrocarbons through separate or mix culture in Zanjan in 2004.
Materials & Methods: In this experimental study naphthalene, toluene and ethyl benzene were used as aromatic hydrocarbons indexes. These substance, as the sole source of carbon were added to the soils which had been inoculated with microbial colonies isolated from polluted areas and four months later microbial count was performed as microbial activity index. The extent of biological and non-biological removal of substances was assessed through gas chromatography procedure and the results were analysed by Mann-Whitney test.
Results: Mean colony counts in which toluene, ethyl benzene and naphthalene had been used as the sole carbon source were 19.7×106, 69.4× 105 and 41.2×106 colony/gr. soil respectively. In the culture containing a mixture of three hydrocarbons the number of colonies was 34×106 in one gram soil. The percentages of biodegradation for three studied hydrocarbons which had been exposed to microorganisms separately were 51, 45 and 69 for toluene, ethyl benzene and naphthalene respectively and when the mixture of the substances was added to the media culture the percentages of removal were 80.1, 65.7 and 63.6 for naphthalene, ethyl benzene and toluene respectively.
Conclusion: Aromatic hydrocarbons are biodegradable by isolating microbial population from oil-polluted soils and preparation of inoculation liquid. Since evaporation is an appropriate method in removal of hydrocarbons, soil rehabilitation through aeration together with microbial inoculation seems a proper method for removal of soil aromatic hydrocarbons.

Background and Objective: Polychlorinated biphenyls (PCBs) are toxic, persistent, bio-accumulate and pose a risk of causing adverse effects on human health and to the environment. PCB compounds exert varios impacts on human depending upon age, route of entry, intensity and frequency of exposure. This study was conducted to determine the effect of UV-C, hydrogen peroxide and solvent on the photodegradation of PCBs. Materials and Methods: The photochemical reactor was of annular geometry (500 ml volume) with a cylindrical low-pressure mercury lamp emitting at 254 nm. The power emitted by the lamp was 6 W. The whole lamp was immersed into a reactor with temperature of 32 ± 2 C. The PCBs were analyzed by GC/ECD equipment. Results: The degradation of total PCBs in terms of one, two and three lamps was 77.5%, 82.9% and 85.2% respectively. The degradation of total PCBs in terms of not using of H2O2 and using 10% and 20% of H2O2 were 74.5%, 79% and 94.5% respectively. Conclusion: The results of this experiments showed that UVC-photolysis of H2O2 leads to a degradation efficiency of PCBs only in the presence of ethanol.

Background and Objective: Oil pollutions are one of the most important environmental problems worldwide that researchers have tried different methods for its degradation. In this regards biological methods attracted the attention of the researchers more than other methods. The main objective of this study was to find microorganisms that could degrade aromatic components in the floating crude oil. Materials and Methods: In order to find such microorganisms, some samples were taken from areas contaminated by petroleum compounds. Microorganisms that could live with crude oil as sole carbon source were isolated. From these samples 14 microorganisms isolated which all were bacteria. The variations of aromatic compounds concentration were measured by gas chromatography method. Results: Among 14 microorganisms two microorganisms that called A-3 and A-14 had more ability and degraded the aromatic components 89% and 86% respectively. By microbiological techniques it was found that A-14 is pseudomonas aerogenusa. Conclusion: The results of this study showed that biodegradation of aromatic compounds that are one of the must toxic materials in crude oil are possible. Also indicated that some oil-degrading microorganisms exist in the nature that do not need to adaptation for biodegradation of oily compounds.