Enhanced dark fermentative hydrogen production under the effect of zero-valent iron shavings

Dark fermentative hydrogen production under the effect of zero-valent metal shavings (iron, aluminum and copper) was studied by using a sucrose medium and a mixed bacterial consortium. The iron shavings were found to be unique to promote the hydrogen production, the hydrogen yield obtained from an optimal dose of 8-16 g/L reached 4.2 mol/mol hexose, doubled compared with that obtained from the control without addition of the iron shavings. The effect was more obvious in low pH buffered medium than in higher buffered medium. The aluminum and copper shavings were either inert or toxic to the cultivation. It is evident that the addition of the zero-valent iron helped maintaining the pH to an optimal range for hydrogen production and drove more reducing equivalents to the production of hydrogen. A microbial corrosion system mediated by the hydrogen producing bacteria was proposed to be responsible for the improvement of hydrogen production.