Biohydrogen production using macroalgal biomass of Laminaria japonica pretreated by gamma irradiation as substrate

Efficient pretreatment methods fervors the availability of substrates for the dark fermentative hydrogen production. Macroalgae Laminaria japonica was pretreated by gamma irradiation to disintegrate the biomass of macroalgae Laminaria japonica for improving hydrogen production by dark fermentation. The experimental results showed that hydrogen production was increased by about 71.4% at 20 kGy radiation. Gamma irradiation at 10–30 kGy can effectively destroy the structure of macroalgae and increase the concentrations of soluble organic compounds, such as soluble chemical oxygen demand (SCOD), protein and polysaccharides, thus provided more available organic compounds for hydrogen production. However, higher dose of irradiation (30 kGy) could decrease the hydrogen production due to the degradation of biodegradable organic compounds and induce the change of microbial structure which can be inferred from the accumulation of lactic acid. The accumulation of lactic acid has negative effect on hydrogen production. In general, gamma irradiation could be used as an efficient method for destroying the biomass structure of macroalgae and enhancing the fermentative hydrogen production but suitable dose should be optimized.