Macro approach analysis of dark biohydrogen production in the presence of zero valent powered Fe°

Recent studies suggest that the supplementation of powdered Fe generates a positive effect on anaerobic fermentation processes but the exact relationship between metals with biological systems has not been fully elucidated. Experimental tests on dark fermentation (DF) were carried out at different Fe concentrations. The anaerobic corrosion (AC) of Fe and the production of H2 through DF of Organic Waste Market (OWM) were tested separately, and subsequently DF tests with Fe at 1 g/L and 2 g/L were carried out. A macroscopic dynamic study was conducted, using R€oels approach based on relaxation times (tR) to establish whether interactions between AC and DF phenomena exist. Experimental bioH2 production and Fe AC were fit by Gompertz and saturative models, respectively to estimate tR. The results of the macro-analysis suggest that both phenomena are concurrent, with tR of the same order of agnitude, generating a positive symbiotic effect. The experimental tests of hydrogen production via DF in presence of 2 g/L of Fe showed an increase of 46% compared with the control tests, of amount of gas and a greater H2/CO2 ratio. The results suggest an enhancement of key enzymes activity due to the action of iron increasing bioH2 production.