Macroalgae, commonly known as seaweed, are rich in carbohydrates which makes them a potential feedstock for biohydrogen production via dark fermentation. In this study, the green macroalgal biomass Ulva sp. was subjected to mild acid-thermal combined pretreatment for the effective release of fermentable sugars. Among the H2SO4 acid concentrations tested, 4% H2SO4 and 121 °C for 40 min attained the highest hydrolysis efficiency with a reducing sugar yield of 0.21 g RS/g biomass. The concentration of fermentation inhibitors furfural and 5-hydroxymethyl furfural were below 1 g/L. Using an initial reducing sugar concentration of 12 g/L and pH 5.5, Clostridium butyricum CGS5 achieved the highest cumulative hydrogen production (2340 mL/L), maximum hydrogen productivity (208.3 mL/L/h), and hydrogen yield (1.53 mol H2/mole RS). In continuous fermentation with 6 h hydraulic retention time, maximum hydrogen productivity increased to 782.45 mL/L/h with a hydrogen yield of 1.52 mol H2/mol hexose. To the best of our knowledge, we report for the first time, biohydrogen production via dark fermentation from green macroalgal biomass Ulva sp. with better yield and productivity.
All Science Journal Classification (ASJC) codes
- Building and Construction
- Mechanical Engineering
- Management, Monitoring, Policy and Law