Combination of bioremediation and electrokinetics for the in-situ treatment of diesel polluted soil: A comparison of strategies

• Published in: The Science of the total environment 2015-11, Vol.533, p.307-316
• Main Authors: Ramírez, Esperanza Mena, Camacho, José Villaseñor, Rodrigo, Manuel A., Cañizares, Pablo
• Format: Article
• Language: English
• Subjects: Biodegradation, Environmental; Diesel polluted soil; Electricity; Electrobioremediation; Electrokinetic soil flushing; Environmental Restoration and Remediation - methods; Gasoline - analysis; Permeable reactive barrier; Petroleum Pollution; Polarity reversal; Soil; Soil Pollutants - analysis
• ISSN: 0048-9697; 1879-1026
• DOI: 10.1016/j.scitotenv.2015.06.127

The aim of this work is to compare different strategies based on electrokinetic soil flushing and bioremediation for the remediation of diesel-polluted soil. Four options were tested at the laboratory scale: single bioremediation (Bio), performed as a control test; a direct combination of electrokinetic soil flushing and biological technologies (EKSF-Bio); EKSF-Bio with daily polarity reversal of the electric field (PR-EKSF-Bio); and a combination of electrokinetic soil flushing and a permeable reactive biological barrier (EKSF-BioPRB). Four batch experiments of 14days duration were carried out for comparing technologies at room temperature with an electric field of 1.0Vcm−1 (in EKSF). A diesel degrading microbial consortium was used. The experimental procedure and some specific details, such as the flushing fluids used, varied depending on the strategy. When using the EKSF-Bio option, a high buffer concentration was required to control the pH, causing soil heating, which negatively affected the biological growth and thus the diesel removal. The PR-EKSF-Bio and the EKSF-BioPRB options attained suitable operating conditions and improved the transport processes for biological growth. Polarity reversal was an efficient option for pH, moisture and temperature control. Homogeneous microbial growth was observed, and approximately 20% of the diesel was removed. The BioPRB option was not as efficient as PR-EKSF-Bio in controlling the operating conditions, but the central biobarrier protected the biological activity. Microbial growth was observed not only in the biobarrier but also in a large portion of the soil, and 29% of the diesel was removed in the short remediation test. [Display omitted] •Good strategy required to reach an efficient combination of EKSF and bioremediation•Direct combination of EKSF and bioremediation lead to infeasible biological cultures•Reversal polarity is a good control strategy in EKSF-bioremediation processes•Combination of EKSF and a biological PRB is the best strategy for removal of diesel