Influence of iron and magnesium on kinetic and mechanism of biohydrogen production from high-strength wastewater

Abstract

In this study, iron/iron-magnesium (Fe/Fe-Mg) additives were prepared through the impregnation of granular activated carbon (GAC) with iron and iron-magnesium (GFM) to enhance biohydrogen production. The microscope observation and chemical analysis revealed that the GAC matrixes were well infused with Fe/Fe-Mg, while the X-ray diffraction analysis revealed the species of metal formed on the GAC as Fe³⁺ and MgH₂. The synergistic effect of Fe and Mg in GFM allowed it for a shorter delay time and higher hydrogen production rate than other additives, indicating their possible use in stimulating the fast release of hydrogen in anaerobic digestion. The co-metabolites analysis revealed that additives ensured biohydrogen production through the different pathways. The plausible mechanisms were through hydrogenases ensured by Fe³⁺ and hydrolysis by MgH₂. GFM gave the best organic matter and nutrient removal efficiency to outperform other additives, suggesting its ability for biohydrogen synthesis and simultaneous wastewater treatment.

Keywords: Biohydrogen; Fe additive; Fe-Mg additive; Wastewater treatment.