Effect of polarity-reversal on electrokinetic enhanced bioremediation of Pyrene contaminated soil

Polycyclic aromatic hydrocarbons (PAHs) contaminated soil was studied under electrokinetic enhanced biodegradation with polarity-reversal. The effects of polarity reversal were investigated on electric current, pH, microbial counts and the spatial distribution of pyrene biodegradation rate during the application of electro-bioremediation. Three types of treatment were conducted: PYR-degrading microbial treatment only (Bio), electro-bioremediation without polarity-reversal (EK-Bio), electro-bioremediation with polarity-reversal at an interval of 2 hours (EK-Bio-PR). After 42 days, EK-Bio-PR maintained a neutral soil pH (7.20) and relatively stable electric current. After running for 17 days, the electric current stabilized around 10 mA in EK-Bio-PR, and which was 5 times than that in KE-Bio. Polarity-reversal enhanced microbial counts, and improved the PYR degradation. The bacterial counts reached up to 4.8 × 1011 cfu/g and the best PYR degradation efficiency was 55.9% in EK-Bio-PR at the end of experiment. Thus, the application of electrokinetics with periodic polarity-reversal enabled better microbial growth and biodegradation, which further improved the overall removal of PAHs pollutant.