Biogenic hydrogen production from household food waste via lactate-driven dark fermentation: A comparative study of single-stage and two-stage configurations

Abstract

Lactate-driven dark fermentation (LD-DF) is a novel approach that integrates lactate production with its con- version to biohydrogen (H2), offering a solution to the inhibition of hydrogen-producing bacteria by lactic acid bacteria while enhancing process stability. This study investigates the efficacy of LD-DF for continuous H2 production by comparing the performance of a two-stage system (lactate fermentation followed by LD-DF) with a single-stage configuration. Household food waste (FW) was used as the substrate, and the impact of varying the hydraulic retention time (HRT; 12, 8, and 6 h) was assessed in both configurations. In the two-stage system, a progressive reduction in HRT resulted in the highest volumetric H2 production rate (HPR) of 4.4 ± 0.4 L-H2/L- d and a hydrogen yield (HY) of 22.9 ± 2.1 mL-H2/g-VSadded. In contrast, the single-stage configuration exhibited a decline in HPR from 3.8 ± 0.6–1.4 ± 0.3 L H2/L-d when the HRT decreased from 12 h to 6 h, although it achieved the highest HY of 39.5 ± 6.0 mL-H2/g-VSadded. Principal component analysis identified a positive correlation between HPR and butyrate concentrations, a trend predominantly observed in the two-stage configuration. Conversely, the HPR negatively correlated with high levels of lactate, acetate, and propionate, which were more prevalent in the single-stage system. Interestingly, Veillonella and Bacteroides were identified as the main H2 producers during LD-DF in both configurations. These findings demonstrate that lactic acid pre- fermentation enhances H2 productivity in FW LD-DF systems and facilitates operation at lower HRTs compared to single-stage configurations