초록
The optimum concentration of volatile fatty acids that maximized the hydrogen production by photobacteria was determined using Box-Behnken and Central Composite designs. A photofermentative hydrogen-producing consortium, obtained from a bio-electrochemical system, was used as inoculum. Rhodopseudomonas palustris was identified in the consortium. Experiments were conducted in anaerobic batch reactors at 30-35 <SUP>o</SUP>C and illuminated by a constant radiation of 5000 lux. Hydrogen production decreased when propionic acid is higher than 715 mg L<SUP>-1</SUP>. Ammonia formation was responsible for the pH increase. A maximum hydrogen production rate of 6.1 mL d<SUP>-1</SUP> L<SUB>culture</SUB><SUP>-1</SUP> h<SUP>-1</SUP> and a maximal amount of hydrogen produced of 108.8 mmol L<SUB>culture</SUB><SUP>-1</SUP> were obtained. Optimal concentrations of acetic, propionic and butyric acids were 1200 mg L<SUP>-1</SUP>, 715 mg L<SUP>-1</SUP> and 1571 mg L<SUP>-1</SUP>, respectively.