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

• EBR with polarity reversal is efficient in the removal of diesel from soil.
• Polarity reversal successes in keeping suitable pH for microbial life.
• By applying 1.5 V cm−1 the bioremediation rate increased by more than 330%.
• Rise in temperature caused by ohmic drops does not affect microbial life.

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.

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