Mobilization and Co-Transport of Pyrene in the Presence of Pseudomonas aeruginosa UG2 Biosurfactants in Sandy Soil Columns |
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| Authors: | Pierre Lafrance Mireille Lapointe |
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| Institution: | Pierre Lafrance is a professor at INRS-Eau (National Institute for Scientific Research, Water Research Center), Universitédu Québec (2800 rue Einstein, C.P. 7500, Sainte-Foy, Québec, Canada, G1V 4C7;phone: 654-2543;fax: 654-2600). His research interests are in the biogeochemkal processes that control organic contaminant fate in soil and ground water. Recent works have included studies to assess the mechanisms responsible for the facilitated transport of organics in soils as well as contributions to the development of soil transport models to evaluate the fate of contaminants. Lafrance holds a Doctorat d'État degree in chemical engineering from Limoges University (France), an M.Sc. degree in environmental engineering from Elcole Polytechnique (Montreal, Quebec) and a B.Sc. degree in chemistry from the Universite du Quebec it Montreal.;Mireille Lapointe is a junior engineer and project manager with Symbiose Consultants (Quebec city), which is involved in the characterization and the treatment of contaminated soils. She received her M.Sc. degree in water sciences from INRS-Eau (Quebec city) in 1996 and her B.Sc.A. degree in geological engineering from UniversitéLaval (Quebec city). Her master's research was relatedio the work described in this paper. |
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| Abstract: | Washing technologies are currently applied for the remediation of contaminated soils. The efficiency of biosurfactants produced by Pseudomonas aeruginosa strains to mobilize some hydrocarbons sorbed on soils has already been demonstrated. However, few studies have been made to define optimal procedures for the injection of these rhamnolipids in soil. This study examines (1) the efficiency of the biosurfactants produced by P. aeruginosa UG2 to mobilize pyrene from a contaminated sandy loam as compared to that of sodium dodecyl sulfate (SDS); (2) the injection procedures (surfactant concentration, pore water velocity, continuous or interrupted flow) that might affect the efficiency of pyrene mobilization using UG2 biosurfactants; and (3) the co-transport of UG2 biosurfactants and pyrene. The UG2 biosurfactants were more efficient for pyrene mobilization than SDS and had much less impact on soil. The mobilization of pyrene was approximately proportional to the mass of UG2 biosurfactants injected for both the 0.25% and the 0.50% (w/v) concentrations used. Pyrene mobilization was not greatly dependent on either the pore water velocity—about 5.9 and 10.2 inch/h (15 and 26 cm/h)—or the duration of flow interruption (5 or 15 h), suggesting that mobilization was not rate limited under these conditions. The rhamnolipids appeared to be weakly retained in the soil. Based on the experimental results, it would be advantageous to use a high UG2 biosurfactant concentration, a high pore water velocity, and possibly a flow interruption of more than 15 h in order to reduce the injected volume and the duration of the treatment required. The 0.25% UG2 biosurfactant concentration greatly enhanced pyrene transport and could facilitate contaminant recovery. |
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