Enhanced bioremediation of benzo [a]pyrene-polluted soil using high-efficiency soil microbial fuel cells with artificial solute transport

Abstract

The degradation ability of benzo [a]pyrene (BaP) was investigated by constructing a solute transport-soil microbial fuel cell (STSMFC) device with artificial water flow to promote solute transport, and the role of sulfur reduction in degradation was also examined. Four comparison devices were set up: STSMFC, SMFC, STSMFC-Open circle (STSMFC-O), and SMFC-O, were set up. The results showed that the voltages of STSMFC and SMFC on day 90 were 687 mV and 601 mV, respectively, and the corresponding potentials of STSMFC-O and SMFC-O were 845 mV and 742 mV, respectively. Solute transport improved the performance of electricity generation and the open-circuit potentials. At the sampling point with the highest water flux near the anode, the BaP removal rates of STSMFC, SMFC, STSMFC-O, and SMFC-O were 77.62 %, 64.53 %, 54.9 %, and 42.73 %, respectively. The combination of solute transport and microbial electrochemical degradation significantly enhanced BaP degradation efficiency. The degradation effect of BaP was positive correlation with sulfate reduction, organic matter consumption, and negative correlation with distance from the anode. Solute transport driven by water flow facilitated the sulfur conversion and organic matter metabolism and changed the community characteristics of sulfate-reducing bacteria (SRB) and degrading bacteria, thus enhancing the degradation of BaP. This study provides a theoretical foundtion for the application of SMFC in the degradation of soil pollutants and sulfur cycling by groundwater.