Environmental remediation: Selection of a biosurfactant for a new method of treatment for soils and waters impacted by Polycyclic Aromatic Hydrocarbons

Abstract : Objectives: Former industrial sites contaminated with Polycyclic Aromatic Hydrocarbons (PAHs) are an environmental and human health concern in Europe. These sites, often former gasworks and coke factories, are close to or are nowadays part of urban areas and are persistent sources of pollution for the underground water that have to be cleaned. PAHs are also a problem for the petroleum industry. The refining of crude oil, the transport, and the petrochemical industry can release PAHs in the environment, leading to health and environment risks. Bioremediation of PAHs in pore water and soils is possible and had already been done but is limited by the low solubility of such molecules, which reduces their bioavailability. Surfactants can enhance the apparent solubility of hydrophobic compounds, like PAHs, entrapping them by the formation of micelles. Chemically-produced surfactants, widely used in soil remediation (i.e. soil washing techniques, etc.) are impaired by their low biocompatibility. Using biosurfactants, produced by bacteria, can improve this biocompatibility and then enhance PAHs bioavailability. The objective of this project is to treat an industrial soil and the groundwater sheet associated, impacted by PAHs with biosurfactant washing and biodegradation at the same time. The present work is part of the Bioxyval project that gathers multiple actors, from public and private sectors, of the soil remediation area. The objective of the project is to develop and implement innovative soil treatment methods, on a former industrial site, with multiple pollutions, including PAHs (former coke factory). Innovative nature of the proposed topic: The aim of the project is to develop an innovative solution for the remediation of the PAHs impacted soil by coupling a soil washing phase with biosurfactants and a stimulated biodegradation phase of the PAHs solubilized in the water. Experimental approach: From the soil samples of the contaminated site, several bacterial cultures had been extracted and isolated. One of them shown abilities to produce biosurfactants and had been selected for further experiments and the optimization of the biosurfactants production. For the optimization of the biosurfactant production, several series of analysis were made, to select the best carbon source, to find the most appropriate culture medium and nutrient balance and to see the influence of others parameters like temperature or the presence of others bacteria isolates. For the PAHs degradation assays, tests were made with soil and water samples from the contaminated site. Injections of the concentrated bacterial strain, of nutrients, or directly biosurfactant were tested. The biosurfactant action was compared with some commercial surfactants and biosurfactants. Results: The biosurfactant production tests show that the isolated bacterial culture was able to produce biosurfactant from an insoluble or a soluble carbon source. The medium with glucose as the carbon source was the one with the fastest production and was selected for further experiment. The presence of both nitrogen and phosphorus nutrient in the culture medium seems to be mandatory for the biosurfactant production for this bacterial isolate, an optimal balance between nitrogen, phosphorus and glucose was found to optimize the speed of the reaction. The bacterial isolate seems able to produce biosurfactant in the presence of other bacteria. Biodegradation trials have already proved the high potential of bacteria for their ability to produce biosurfactant, which pushes the PAHs up to micellar state. On the water samples, evidences of the use of the produced biosurfactant for the PAHs degradation had been found. The second phase of the project is to test both the biosurfactant production, the PAHs solubilization and the PAHs biodegradation in soil column to see the influence of the physical parameters of the soil on the remediation process. During the final step of this work, those lab trials will be extended to an in situ pilot treatment on an industrial site.
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Contributor : Florian Cazals <>
Submitted on : Wednesday, July 3, 2019 - 11:21:45 AM
Last modification on : Friday, August 23, 2019 - 12:32:02 PM

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Florian Cazals, David Huguenot, Stéfan Colombano, Stéphanie Betelu, Nathalie Galopin, et al.. Environmental remediation: Selection of a biosurfactant for a new method of treatment for soils and waters impacted by Polycyclic Aromatic Hydrocarbons. GeoEnergy Days, Pole Avenia, Jul 2018, Pau, France. ⟨hal-02171848⟩

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