Document Type : Research Article
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Abstract
The contamination of ecosystem components with petroleum and its derivatives is considered as one of the most crucial environmental threat in Iran, particularly in southern areas. Bioremediation has frequently been regarded as an appropriate and more practical alternative to clean-up petroleum hydrocarbons in the contaminated environments. Bioremediation optimizes conditions for microbial hydrocarbon degradation and uses the microorganisms and plants potential to metabolize contaminants resulting in their removal or attenuation in situ. This study aims at remedying an aged petroleum-contaminated soil using bioaugmentation and phytoremediation techniques. A consortium has been prepared using oil-degrading bacteria; 10% oil-contaminated soil was then inoculated with the consortium. Additionally, oat and/or barley were planted in certain treatments to separately evaluate the effects of plant-bacteria interaction on Total Petroleum Hydrocarbon (TPH) degradation and inoculum's efficiency. TPH degradation value under unplanted and uninoculated conditions was only 2.4% in the studied petroleum -contaminated soil after 4 months. However, the presence of the two plants elevated TPH degradation up to 30%, and bacterial inoculation resulted in only 20% TPH degradation. The significance of the plants in enhancing TPH degradation could be probably explained by promoting microbial populations, growth and activities. The highest amount of TPH degradation recorded was 44% and was observed with inoculated plants. The presence of plants in petroleum-contaminated soils promoted microbial populations and activities with increased microbial respiration and biomass well developed petroleum-degrading microbial population and decreased microbial metabolic quotient (qCO2), hence, increased biodegrading of hydrocarbons.
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