Intermittent low-strength ultrasonication enhances methane production by stimulating direct interspecies electron transfer in microbial electrolysis cell-anaerobic digestion systems

초록

This study investigated the effects of intermittent low-strength ultrasonication (LS-ultrasonication) on the performance of a microbial electrolysis cell-anaerobic digestion (MEC-AD) system. However, the effect of ultrasonication interval in MEC-AD systems remains unclear. Ultrasonication was intermittently applied at 0.005 W mL- 1 with pulse intervals of 30, 60, and 120 s. Methane production in the ultrasonication-assisted MEC systems increased by 16.9-40.9% compared with the control MEC. The highest methane yield was obtained under the shortest interval condition (1 s per 30 s), reaching 304.8 +/- 41.0 mL g- 1 VS_added. Hydrogen sulfide emissions increased by 17.4-35.3% relative to the control. Microbial community analysis revealed increased relative abundances of exoelectrogenic, syntrophic, and sulfate-reducing bacteria under LS-ultrasonication conditions. In addition, the archaeal community was dominated by Methanothrix, a representative microorganism associated with direct interspecies electron transfer (DIET). These results suggest that intermittent LSultrasonication stimulated DIET-associated microbial activity, thereby enhancing methane production in the MEC-AD system.

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