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

Abstract

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 14 days duration were carried out for comparing technologies at room temperature with an electric field of 1.0 V cm(-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.

Effect of electric field on the performance of soil electro-bioremediation with a periodic polarity reversal strategy

“…The experimental setup used in the tests was described elsewhere (Ramírez et al, 2015). The soil used was kaolinite clay (provided by Manuel Riesgo Chemical Products, Madrid, Spain).…”

Electro-assisted groundwater bioremediation: Fundamentals, challenges and future perspectives

“…It was found that the rates of phenanthrene losses from creosote-contaminated soil were 10-times higher than those for the control systems without current, while no significant degradation of phenanthrene was observed in the abiotic control (Niqui-Arroyo et al, 2006). Significantly accelerated degradation of diesel hydrocarbon in a bio-PRB by electrochemical stimulation (29% versus 12% removal within two weeks) under an applied power density of 66 kW h/m 3 was also demonstrated (Ramírez et al, 2015a) (Table 1). In comparison, only 25% phenanthrene removal was attained in a sole electrokinetic system with an energy consumption of 500 kW h/m 3 after three months (López-Vizcaíno et al, 2014).…”

Integrating Electrokinetic and Bioremediation Process for Treating Oil Contaminated Low Permeability Soil

“…In addition, the surfactant may serve as a useful co-substrate for microorganisms. The microorganisms at the beginning of the study amounted to 8x10 6 CFU / ml and on average increased on the third day before finally decreasing until the seventh day. This decrease occurs due to changes in drastic environmental conditions such as decreased pH and moisture content.…”

“…Electrokinetic technology is known to be used as a alternative for treating contaminated soil using constant low voltage gradient [5], [6]. The electrochemical process is used to improve bioavailability and biomixing on contaminated soil so that improving the efficiency and effectiveness of the bioremediation process.…”