Biohydrogen Production from Industrial Waste: The Role of Pretreatment Methods

This study aimed to investigate the effectiveness of dark fermentation in biohydrogen production from agro-industrial wastes, including apple pomace, brewer’s grains, molasses, and potato powder, subjected to different pretreatment methods. The experiments were conducted at a laboratory scale, using 1000 cm3 anaerobic reactors at a temperature of 35 ◦C and anaerobic sludge as the inoculum. The highest yield of hydrogen was obtained from pre-treated apple pomace (101 cm3/g VS). Molasses, a less complex substrate compared to the other raw materials, produced 25% more hydrogen yield following pretreatment. Methanogens are sensitive to high temperatures and low-pH conditions. Nevertheless, methane constituted 1–6% of the total biogas under these conditions. The key factor was appropriate treatment of the inoculum, to limit competition from methanogens. Increasing the inoculum dose from 150 cm3/dm3 to 250 cm3/dm3 had no further effect on biogas production. The physicochemical parameters and VFA data confirmed the stability and usefulness of activated sludge as a source of microbial cultures for H2 production via dark fermentation.