Biohydrogen from food waste in a discontinuous process: Effect of HRT and microbial community analysis

• The highest H2 production rate was obtained at an HRT of 24 h.
• Low diversity and low evenness were obtained independently of the HRT.
• The genus Megasphaera was found to be the dominant genus in the microbial community.

There are several parameters that affect the hydrogen (H2) production when using organic solid waste in a discontinuous process, such as the hydraulic retention time (HRT). To optimize the process, it is necessary to determine the HRT such that the H2 production is maximized. The objective of this study is to evaluate the effect of different HRTs on the hydrogen production in an anaerobic sequencing batch reactor (ASBR) using food waste as the substrate. The microbial community was analyzed and correlated with the reactor performance. The results showed that the highest percentage of H2 in biogas, maximum volumetric H2 production, and maximum H2 production rate was obtained with an HRT of 24 h. The percentage of H2 in biogas varied from 22 to 53%, which depended on the HRT. Acetic acid was the main volatile fatty acid obtained. The highest propionic acid production was observed with an HRT of 6 h, which was related to a decrease in H2 generation, where a low diversity and low evenness were obtained compared with those of the reactor samples obtained from different HRTs. The genus Megasphaera was found to be the dominant genus in the microbial community.