Alternating current enhanced bioremediation of petroleum hydrocarbon-contaminated soils

In this work, bioremediation was applied with sinusoidal alternating current (AC) electric fields to remove petroleum hydrocarbon (TPH) for soil remediation. Applying AC electric field with bioremediation (AC+BIO) could efficiently remove 31.6% of the TPH in 21 days, much faster than that in the BIO only system (13.7%) and AC only system (5.5%). When the operation time extended to 119 days, the AC+BIO system could remove 73.3% of the TPH. Applying AC electric field (20-200 V/m) could maintain the soil pH at neutral, superior to the direct current electric field. The maximum difference between soil temperature and the room temperature was 1.9 degrees C in the AC (50 V/m) +BIO system. The effects of AC voltage gradient (20-200 V/m) on the microorganisms and TPH degradation efficiency by AC+BIO were investigated, and the optimized AC voltage gradient was assessed as 50 V/m for lab-scale experiments. The microbial community structures in the BIO and AC+BIO systems were compared. Although Pseudomonas was the dominant species, Firmicutes became more abundant in the AC+BIO system than the BIO system, indicating their adaptive capacity to the stress of the AC electric field. Real petroleum-contaminated soil was used as a reaction matrix to evaluate the performance of AC+BIO in the field. The initial current density was about 0.2 mA/cm(2), voltage gradient was about 20 V/m, and the average TPH degradation rate was 8.1 mu g/g(dry soil) per day. This study provided insights and fundamental supports for the applications of AC+BIO to treat petroleum-polluted soils.

Automated summary

This study investigated the application of bioremediation with sinusoidal alternating current electric fields for soil remediation, showing that the AC+BIO system was more efficient in removing petroleum hydrocarbons compared to BIO or AC alone. The study also found that the appropriate AC voltage gradient had an impact on microbial communities and TPH degradation efficiency. Further research and practical applications are warranted based on the insights provided by this study.