Effect of zero-valent iron nanoparticles on taxonomic composition and hydrogen production from kitchen waste

This study investigated the effects of varying zero-valent iron (ZVI) (0 to 5,000 mg/L) on fermentative hydrogen (H₂) production, metabolic pattern, and taxonomic profile by using kitchen waste as substrate. The study demonstrated that the supplementation of 500 mg ZVI/L resulted in the highest H₂ yield (219.68 ± 11.19 mL H₂/g-volatile solids (VS)_added), which was 19% higher than the control. The metabolic pattern analysis showed that acetic and butyric acid production primarily drove the H₂ production. The taxonomic analysis further revealed that Firmicutes (relative abundance (RA): 80-96%) and Clostridium sensu stricto 1 (RA: 68-88%) were the dominant phyla and genera, respectively, during the exponential gas production phase, supporting the observation of accumulation of acetic and butyric acids. These findings suggest that supplementation of ZVI can enhance H₂ production from organic waste and significantly influence the metabolic pattern and taxonomic profile, including the metalloenzymes.