Measurement of biodegradation rate constants of a water extract from petroleum-contaminated soil

The study of biodegradation rate constants of petroleum products in water extract from contaminated soil presents an important component in the evaluation of bioremediation process. In this study, soil samples were gathered from an industrial site which was used for maintenance and storage of heavy equipment used in the oil and gas exploration and production industry. The petroleum contaminants were extracted from the soil using distilled water. This water extract was used as the substrate to acclimate a microbial community and also for the biological kinetic studies. Kinetic studies were carried out in batch reactors, and the biodegradation rates were monitored by a computer-controlled respirometer. The BOD data were analyzed by using the Monod equation. Experimental results give the average value of the maximum rate constant as 0.038 mg BOD/(mg VSS hr) and the average value of the substrate concentration of half rate as 746 mg BOD/λ. A GC/MS analysis on the samples of the test solutions before and after 5 days of biological oxidation indicates that the hydrocarbons initially present in the solution were degraded.