Synchronously accelerated petroleum hydrocarbon removal in soil and leachate by the bioelectrochemical systems for over 1200 days

Bioelectrochemical system has developed to remediate petroleum contamination in soil and groundwater. However, little is known about the remediation performance under a long-term operation. Here, we constructed a soil-leaching system that operated uninterruptedly for 1280 days to remove petroleum hydrocarbons from soil and simulated groundwater. A 65% increment for degradation with the iron redox was observed compared to the natural degradation (9081 mg/kg of removal relative to original soil). Notably, the recalcitrant organics was decomposed by the biocurrent stimulation on the microbial metabolism, supporting by 128% lower of humification degree and 35% higher of microbial metabolism. Consequently, contents of humic acid- and fulvic acid-like compounds increased by 100% and 55% respectively, and the carbohydrate enhanced by 108% with more than 55% proportion of compounds containing CHO only in dissolved organic matter. While, the aromatics decreased by 33% under the biocurrent stimulation based on fourier transform ion cyclotron resonance mass spectrometry. Network analysis revealed that biocurrent can facilitate the connectivity of functional microorganisms due to the biocurrent directed selection enriching Fe-reducing bacteria Geobacter, Thiobacillius and Clostridium_sensus and enhancing the cooperation between the functional genes (Fro2, FOB, MtrC, and alkB) and the species. Overall, this study provides insights into the long-term in-situ bioelectrochemical degradation of petroleum pollution in soil and groundwater.