A Comparative Study on the Effects of Biostimulation and Bioaugmentation on the Remediation of Contaminated Sediments with Crude Oil in the Persian Gulf

Introduction: Crude oil pollution in the Persian Gulf is a major problem in this important marine environment. Today, the use of biological degradation methods to remove these pollutants is considered. The purpose of the present study is to compare the two methods of biological stimulation and biological enhancement for the degradation of sediments contaminated with crude oil in the Persian Gulf. Materials and Methods: In this research, six types of microcosms were designed to understand the effectiveness of biostimulation and bioaugmentation on the microbial population of Khark Island sediments. Indicators such as the quantity of degrader, heterotrophs, and the rate of crude oil degradation were investigated at different times and finally, the degradation over time was measured by the Gas Chromatography method. Results: The results of this study showed that the combined microcosm of biostimulation and bio-augmentation (SB) with the amount of heterotrophic bacteria (equal to 3.9 x 106) and degrader (equal to 1 x 106) had the highest quantity. Population dynamics in microcosms were also studied and the lowest quantity of heterotrophic bacteria with a numerical value of 1x104 was related to natural sediments. The statistical results of this research proved that there is a significant relationship between the type of method chosen for biodegradation with the sampling time and the quantity of the dynamic population, and finally, with the increase of incubation time, the biodegradation of oil in all microcosms increased significantly (95%), but the best biodegradation of oil was related to the integrated microcosm of biostimulation and bio-augmentation. Discussion and Conclusion: By using the type of biological remediation method according to the nature of the contaminated sediments, oil-contaminated sediments can be rehabilitated with the help of biological methods and contribute to the stability of marine ecosystems.