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

Abstract

In this work, it is studied the effect of the electric fields (within the range 0.0-1.5 V cm(-1)) on the performance of electrobioremediation with polarity reversal, using a bench scale plant with diesel-spiked kaolinite with 14-d long tests. Results obtained show that the periodic changes in the polarity of the electric field results in a more efficient treatment as compared with the single electro-bioremediation process, and it does not require the addition of a buffer to keep the pH within a suitable range. The soil heating was not very important and it did not cause a change in the temperature of the soil up to values incompatible with the life of microorganisms. Low values of water transported by the electro-osmosis process were attained with this strategy. After only 14 d of treatment, by using the highest electric field studied in this work (1.5 V cm(-1)), up to 35.40% of the diesel added at the beginning of the test was removed, value much higher than the 10.5% obtained by the single bioremediation technology in the same period.

Innovative methods of ground improvement for railway embankment peat fens foundation soil

“…A constant voltage gradient of 0.4 V/cm was maintained throughout the tests as recommended in the literature in order to prevent potential harm to the bacteria (Mizuno and Hori, 1988;Hassan et al, 2016). For the same reasons, periodic polarity reversal was applied every 24 h recommended for a better uniformity hence effectiveness of the treatment but also to prevent high pH gradients that could also be harmful to the bacteria (Mena et al, 2016). To ensure that both voltage and pH did not considerably change during treatment, measurements of these quantities were performed at 0 mm, 50 mm and 100 mm away from the electrodes locations of the sample throughout the treatment; pH of the solutions was also monitored inside both electrolyte chambers during the treatment.…”

Removal of chlorsulfuron and 2,4-D from spiked soil using reversible electrokinetic adsorption barriers

“…For this reason, advantages of reversible changes in the polarity were also pointed out in the literature [38]. A comprehensive example was shown with the removal of diesel pollution from soils [39,40], in which the periodic reversion in the polarity did not only improve the efficiency but it also helped to regulate the pH (preventing extreme pH even near to the electrode wells) and to avoid the depletion of ionic species in the soil.…”

“…Each day the polarity of electrodes was reverted. This arbitrary period was chosen taking into account previous experience of our group in the REKAB technology [44,45]. In this work, not only results of the REKAB technology but also a comparison with EKSF is going to be carried out.…”

Implementation of biocementation for a partially saturated problematic soil of the UK railway network

“…A constant voltage gradient of 0.4 V/cm was maintained throughout the tests as recommended in the literature in order to prevent potential harm to the bacteria [18][19]. Periodic polarity reversal was applied every 24 h, which is recommended for a better uniformity of the treatment but also to prevent high pH gradients that could be harmful to the bacteria [20]. To ensure that both voltage and pH did not change considerably during treatment, measurements of these quantities were performed at 0 mm, 50 mm and 100 mm away from the electrodes locations of the sample throughout the treatment; pH of the solutions was also monitored inside both electrolyte chambers during the treatment.…”