Biohydrogen Production from Buckwheat Residue Using Anaerobic Mixed Bacteria

In the world, wastes/residues from agricultural activities are rapidly increasing, causing environmental problems. These wastes/residues can be used for the production of biohydrogen as a raw material. In this context, buckwheat crop residue, which has not been found in any study on biohydrogen production potential in the literature research, was investigated for biological hydrogen production via the dark fermentation method. This study was conducted in anaerobic batch bioreactors containing buckwheat or buckwheat extract + pretreated anaerobic mixed bacteria + nutrients, in a darkroom, at 37 ± 1 °C. Gas analyses, organic acid analyses and taxonomic content analyses were performed in bioreactors under different operating conditions (initial pH and organic loading rate). Biological hydrogen production was determined in all bioreactors. In addition, hydrogen production was found to be higher in bioreactors where biomass was used directly. The maximum biohydrogen production was determined to be 11,749.10−4 mL at 1.20 g. buckwheat/L and 446.10−4 mL at 1.20 g. buckwheat extract/L at pH 4.5. According to the taxonomic content species’ level ratios, (i) in bioreactors where biomass was used directly, Hathewaya histolytica and Clostridium butyricum were detected at pH values of 4.5 and 4.0, respectively; and (ii) in bioreactors where biomass extract liquid was used, Clostridium butyricum and Clostridium tertium were determined as the most dominant bacteria at pH values of 4.5 and 4.0, respectively.