Revista de peligros ambientales

Applied Growth Kinetic Models for Crude Oil Spill Bioremediation in a Batch Scale Bioreactor

Abstract

Munna Bhattacharya, Dipa Biswas and Sugata Guchhait

Hydrocarbon pollution occurs mainly by accidental oil spills, deliberate discharge of ballast waters from oil tankers and bilge waste discharges; causing site pollution and serious adverse effects on the environment. As compared to physical and chemical methods, such as booms, skimmers, adsorbents, chemical surfactants, oxidants, etc., bioremediation is a sustainable technique for restoration of oil-polluted sites, in which highly hazardous oily materials can be easily mineralized to harmless end products at very low cost using indigenous microorganisms. In this study, bioremediation experiments of artificially crude oil contaminated water was carried out in a batch scale bioreactor using the mixed culture of Ochrobactrum pseudintermedium sp. C1 and Bacillus cereus sp. K1. The effect of initial crude oil concentrations (1 to 10% v/v) on the growth and biodegradation rate were studied. The initial rate of growth and biodegradation increased with initial crude oil concentration up to 4% (v/v), but further increase in oil concentration resulted in a gradual decrease in the rate of biodegradation due to substrate inhibition. Both Monod and Haldane kinetic models were applied to evaluate the growth kinetic parameters (µmax, Ks, Ki, Smax, Yx/s). It was found that the Monod model was unable to present the growth parameters over the defined concentration range. However, Haldane model perfectly fitted with the experimental data and the following kinetic parameters were obtained: µmax=0.085 hr-1; Ks=32722.83 mg/dm3; Ki=53205.64 mg/dm3; Smax=41725.76 mg/dm3. These results showed that the mixed culture was able to utilize a considerably high concentration of crude oil and could be very effective in crude oil biodegradation for restoration of highly oil contaminated sites.