Effect of static magnetic field on hydrogen and n-caproic acid production by dark fermentation with no pretreatment excess sludge as inoculum

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. External SMF by adding magnets on both sides of the reactor could accelerate the enrichment of Ethanoligenens and improve the activity of reduced coenzyme I so that the maximum hydrogen yield could reach 6.4 mol H2/mol glu. Moreover, the n-caproic acid production could be increased based on the enrichment of carbon chain extension microorganisms. The decline of hydrogen production was mainly due to hydrogenotrophic methanogenesis and acetic acid accumulation. This study provides a new direction for better understanding the interaction mechanism between magnetic field and microorganisms and improving the value of biological hydrogen production process.