Electro-stimulation modulates the synergistic interaction of microbe and electrode for sulfur recovery in the co-conversion of benzene and sulfur dioxide

Water treatment containing benzene and sulfur dioxide disposal are two important environmental issues. Simultaneous achievement of these two goals is extremely attractive. Here, a series of laboratory scale bioelectrochemical reactors were constructed to investigate the co-conversion of benzene and sulfur dioxide. The results showed that benzene and sulfur dioxide exhibited synergistic conversion, and the auxiliary voltage enhanced the conversion process. The maximum conversion rate of benzene was observed in the bioreactor with 1.6 V voltage, attaining 42.93 mg·L -1 ·d -1 , which is 1.28 times the value of the bioreactor without applied voltage. Elemental sulfur recovery was achieved during the co-conversion which improved the resource value of the treatment process. The genes of ubiX , ubiD , hbaA , and ppsABC , which have been reported to activate the benzene ring under anaerobic conditions, were detected. Aerobic benzene oxidizing genes of dmpBCD and tmoCF were significantly enriched in the bioreactor with 1.6 V. Pseudomonas sp., Stenotrophomona s sp. and Aquamicrobium sp. are dominant microbial genera. Based on microbial metabolic conservation, transformation products and metagenomic evidence, the potential synergistic pathway is proposed that benzene is activated by Pseudomonas sp. through hydroxyl addition fermentation to produce simple organic compounds, which are further used by Aquamicrobium sp. and Stenotrophomona s sp. for sulfur reduction. In the bioreactor with 1.6 V voltage, trace oxygen plays an important role, which promotes the aerobic oxidation of benzene and sulfur recovery. This study provides scientific insights into the synergistic control of benzene and sulfur, and contributes to the establishment of sustainable environment relationship.