Pilot tests for the optimization of the bioremediation strategy of a multi-layered aquifer at a multi-focus site impacted with chlorinated ethenes
A multi-layered aquifer in an industrial area in the north of the Iberian Peninsula is severely contaminated with the chlorinated ethenes (CEs) tetrachloroethylene, trichloroethylene, <em>cis</em>-1,2-dichloroethylene, and vinyl chloride. Both shallow and deep aquifers are polluted, with...
| Autores: | , , , , , |
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| Tipo de recurso: | artículo |
| Estado: | Versión aceptada para publicación |
| Fecha de publicación: | 2024 |
| País: | España |
| Institución: | Varias* (Consorci de Biblioteques Universitáries de Catalunya, Centre de Serveis Científics i Acadèmics de Catalunya) |
| Repositorio: | Recercat. Dipósit de la Recerca de Catalunya |
| OAI Identifier: | oai:recercat.cat:2445/215728 |
| Acceso en línea: | https://hdl.handle.net/2445/215728 |
| Access Level: | acceso embargado |
| Palabra clave: | Contaminació de l'aigua Bioremediació Aqüífers Hidrogeologia Water pollution Bioremediation Aquifers Hydrogeology |
| Sumario: | A multi-layered aquifer in an industrial area in the north of the Iberian Peninsula is severely contaminated with the chlorinated ethenes (CEs) tetrachloroethylene, trichloroethylene, <em>cis</em>-1,2-dichloroethylene, and vinyl chloride. Both shallow and deep aquifers are polluted, with two differentiated north and south CEs plumes. Hydrogeochemical and isotopic data (<em>δ</em><sup>13</sup>C of CEs) evidenced natural attenuation of CEs. To select the optimal remediation strategy to clean-up the contamination plumes, laboratory treatability studies were performed, which confirmed the intrinsic biodegradation potential of the north and south shallow aquifers to fully dechlorinate CEs to ethene after injection of lactate, but also the combination of lactate and sulfidized mZVI as an alternative treatment for the north deep aquifer. In the lactate-amended microcosms, full dechlorination of CEs was accompanied by an increase in 16S rRNA gene copies of <em>Dehalococcoides</em> and <em>Dehalogenimonas</em>, and the <em>tceA</em>, <em>vcrA</em> and <em>bvcA</em> reductive dehalogenases. Three <em>in situ</em> pilot tests were implemented, which consisted in injections of lactate in the north and south shallow aquifers, and injections of lactate and sulfidized mZVI in the north deep aquifer. The hydrogeochemical, isotopic and molecular analyses used to monitor the pilot tests evidenced that results obtained mimicked the laboratory observations, albeit at different dechlorination rates. It is likely that the efficiency of the injections was affected by the amendment distribution. In addition, monitoring of the pilot tests in the shallow aquifers showed the release of CEs due to back diffusion from secondary sources, which limited the use of isotopic data for assessing treatment efficiency. In the pilot test that combined the injection of lactate and sulfidized mZVI, both biotic and abiotic pathways contributed to the production of ethene. This study demonstrates the usefulness of integrating different chemical, isotopic and biomolecular approaches for a more robust selection and implementation of optimal remediation strategies in CEs polluted sites. |
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