Analysis of the performance and microbial community of continuous dark fermentation combined with steady static magnetic field

The effect of external static magnetic field on hydrogen production and its mechanism were studied by continuous dark fermentation with no pretreatment excess sludge as inoculum. The results showed that under conditions of 37 ± 1 ℃, HRT 8 h, OLR 15 g/(L· d) and no control of influent pH, 78 mT external static magnetic field by adding magnets on both sides of the reactor could accelerate the enrichment of Ethanoligenens and improve the activity of reduced coenzyme I (96%), ferredoxin oxidoreductase (29%) and pyruvate: ferredoxin oxidoreductase (7%) so that the maximum hydrogen productivity could reach 1.657 L H2/L, which was 5 times higher than that of non-magnetic group. Moreover, the n-caproic acid production could also increase due to the enrichment of carbon chain elongation microorganisms. The decline of hydrogen production was mainly due to hydrogenotrophic methanogenesis and acetic acid accumulation. This study was benefit to understand the interaction mechanism between magnetic field and microorganisms during the process of biological hydrogen production.