Improvement of hydrogen production by biological route using repeated batch cycles

Hydrogen is considered a very clean energy source, since its combustion releases mainly water as a reaction product. Besides, it has the advantage of having the highest energy density when compared to any other fuel. This work studied the hydrogen production applying dark fermentation by a heat shock pre-treated microbial consortium. A repeated batch cycle operation was evaluated by adding glucose or lactose in an isolated, alternated or simultaneous ways, in order to keep the production of hydrogen for a longer time. Fermentations with simultaneous addition of glucose and lactose promoted maximum productivity of 168.27 mmol H2 L−1 day−1. Nevertheless, the alternation of two carbon source (glucose and lactose) allowed keeping the culture active with potential to hydrogen production for a period of time higher than 900 h. At the end of fermentation, the main products were lactic acid and butyric acid, followed by acetic acid, ethanol and propionic acid.