Enhanced anaerobic degradation of organic pollutants in a soil microbial fuel cell

The anaerobic degradation of organic pollutants is generally slower than under aerobic conditions. With the aim of in situ remediation of anoxic soils contaminated with organic pollutants, an insertion-type soil microbial fuel cell (MFC) was constructed and inserted into waterlogged soil to enhance the biodegradation of phenol and simultaneously electricity generation. The highest power density reached 29.45 mW/m2, and an internal resistance of approximately 140 Ω was obtained under an external loading of 100 Ω. Under closed-circuit conditions, 90.1% of the phenol was removed after the soil MFC had operated for 10 days, but the degradation rates were only 27.6% and 12.3% under open-circuit and non-MFC conditions, respectively. The phenol degradation rate constant (k) under closed-circuit conditions was 0.390/day, which was approximately 23 times higher than under non-MFC conditions. The degradation of phenol was also positively correlated with the removal of soluble COD and particulate COD, indicating that the removal of organic pollutants and COD in waterlogged soils could be enhanced by a soil MFC system coupled with electricity generation. This method has important implications for soil remediation because it may accelerate the transformation or degradation of some toxic organic pollutants under anoxic conditions.

• An insertion-type soil microbial fuel cell was constructed and applied for in situ soil remediation.
• The degradation of phenol in waterlogged soil under closed-circuit conditions was higher than under non-MFC conditions.
• The degradation of phenol was positively correlated with the removal of soluble COD and particulate COD.
• The removal of organic pollutants and COD in waterlogged soils could be enhanced by simple insertion of the soil MFC.