Feasibility of biohydrogen production from Gelidium amansii

The feasibility of hydrogen production from red algae was investigated. Galactose, the main sugar monomer of red algae, was readily converted to hydrogen by dark fermentation. The maximum hydrogen production rate and yield of galactose were 2.46 L H2/g VSS/d and 2.03 mol H2/mol galactoseadded, respectively, which were higher than those for glucose (0.914 L H2/g VSS/d and 1.48 mol H2/mol galactoseadded). The distribution of soluble byproducts showed that H2 production was the main pathway of galactose uptake. 5-HMF, the main byproduct of acid hydrolysis of red algae causes noncompetitive inhibition of H2 fermentation. 1.37 g/L of 5-HMF decreased hydrogen production rate by 50% compared to the control. When red algae was hydrolyzed at 150 °C for 15 min and detoxified by activated carbon, 53.5 mL of H2 was produced from 1 g of dry algae with a hydrogen production rate of 0.518 L H2/g VSS/d. Red algae, cultivable on vast tracts of sea by sunlight without any nitrogen-based fertilizer, could be a suitable substrate for biohydrogen production.