Abstract
The world must find a way of producing fuel from renewable energy sources to replace the fossil fuels. The sustained production of hydrogen by Chlorella sp., a unicellular green alga, can be achieved in sulfur-deprived culture conditions, besides integrating dark and light bio-hydrogen production strategy. Moreover, dark fermentation carried out by bacterial consortium in anaerobic systems provides organic acids such as acetic, lactic, propionic, butyric. These compounds may be used by the algae as a carbon source to enhance the hydrogen production. In addition, acetate and citrate can be used by Chlorella sp. to increase the cell respiration rates due to inhibition of O2 production during photosynthesis, and consequently, improving H2 synthesis. This work evaluated the effect of the sulfur-deprived medium (WC) containing yeast extract and milk whey permeate, besides sugarcane molasses combined with milk whey permeate to bio-hydrogen production by Chlorella sp. Furthermore, it was evaluated the influence of a hybrid system in which a conditioned medium obtained from dark fermentation by bacterial consortium was used as substrate by algae on the hydrogen productivity and substrate conversion efficiency by green algae. The results showed that the hybrid systems and the use of complex carbon source can improved the biohydrogen production.
