초록
Hydrogen gas production from cheese whey powder (CWP) solution by thermophilic dark fermentation was investigated at 55 <SUP>o</SUP>C. Experiments were performed at different initial total sugar concentrations varying between 5.2 and 28.5 g L<SUP>-1</SUP> with a constant initial bacteria concentration of 1 g L<SUP>-1</SUP>. The highest cumulative hydrogen evolution (257 mL) was obtained with 20 g L<SUP>-1</SUP> total sugar (substrate) concentration within 360 h while the highest H<SUB>2</SUB> formation rate (2.55 mL h<SUP>-1</SUP>) and yield (1.03 mol H<SUB>2</SUB> mol<SUP>-1</SUP> glucose) were obtained at 5.2 and 9.5 g L<SUP>-1</SUP> substrate concentrations, respectively. The specific H<SUB>2</SUB> production rate (SHPR = 4.5 mL h<SUP>-1</SUP> g<SUP>-1</SUP>cells) reached the highest level at 20 g L<SUP>-1</SUP> total sugar concentration. Total volatile fatty acid (TVFA) concentration increased with increasing initial total sugar content and reached the highest level (14.15 g L<SUP>-1</SUP>) at 28.5 g L<SUP>-1</SUP> initial substrate concentration. The experimental data was correlated with the Gompertz equation and the constants were determined. The optimum initial total sugar concentration was 20 g L<SUP>-1</SUP> above which substrate and product (VFA) inhibitions were observed.