Biomass pretreatment, bioprocessing and reactor design for biohydrogen production: a review

The negative effects of the accelerating climate change due partly to fossil fuel consumption is calling for the rapid development of sustainable energies such as biohydrogen, which is produced using microorganisms. Here we review biohydrogen production from biomass, with focus on biomass pretreatment, fermentative production, factors affecting production, bioreactors, kinetics and modeling, and improved production with nanoparticles. Pretreatments include chemical, physical and biological methods. Hydrogen production is done by photo-fermentation or dark fermentation. Influencing factors comprise pH, temperature, hydraulic retention time, and the presence of fermentation inhibitors. Continuous stirred tank-, anaerobic fluidized bed-, anaerobic sequencing batch-, up-flow anaerobic sludge blanket- and dynamic membrane reactors are used. Additives include cobalt, nickel and iron nanoparticles. Compared to thermochemical, photochemical and electrochemical processes, biohydrogen production needs more time but is easy to operate, cost-effective and environmentally friendly.