Enhanced Removal of Hydrocarbons from Crude Oil Sludge through Phytoremediation with Biosurfactant-producing Rhizobacteria

Abstract

Discharge of crude oil (or its products) during the extracting, refining, and transporting into the environment have caused serious environmental distress due to their highly hydrophobic resistance, and persistence in nature and very difficult to be remediated from the environment. Therefore, an environmentally conscious approach to enhance the bioavailability (or solubility) of petroleum hydrocarbon pollutants in soil involves the utilization of biosurfactants. Biosurfactants play a crucial role in enhancing the desorption and solubilization of petroleum hydrocarbons, facilitating their assimilation by microorganisms. This research investigated the application of biosurfactant supplementation derived and purified from rhizobacteria of Scirpus grossus, which are capable of producing biosurfactants and degrading hydrocarbons, in the context of phytoremediation. The crude oil sludge used in this study was obtained from an industrial area containing 56,600±3;900 mg/kg of total petroleum hydrocarbon (TPH). The crude oil sludge was inoculated with biosurfactant, sodium dodecyl sulfate (SDS) as commercial surfactant and only with the presence of S. grossus in the vegetated tanks and monitored for 90 days in a greenhouse. The results indicated that the growth of S. grossus with the addition of biosurfactant was improved and new saplings were produced. After a 90-day exposure period, the removal efficiency of TPH from the soil demonstrated significant increases, reaching 90.3%, 84.1%, and 73.7% when treated with biosurfactant+S. grossus, SDS+S. grossus, and S. grossus only respectively. These percentages were notably higher compared to the non-planted control crates (CC) where the removal efficiency was only 17.9%. These results provide evidence that the introduction of biosurfactant through inoculation can elevate the bioavailability of organic pollutants, consequently augmenting their microbial degradation in the soil.