Different micronutrients are essential for bacterial fermentative metabolism. In particular, some metallic ions, like iron, are able to affect the biological H₂production. In this study, batch tests were carried out in stirred reactors to investigate the effects of Fe²⁺ concentration on fermentative H₂production from two different organic fractions of waste: source-separated organic waste (OW) from a composting plant including organic fraction of municipal solid waste and food waste (FW) from a refectory. Iron supplementation at 1000 mg/L caused twofold increment in the cumulative H₂production from OW (922 mL) compared with the control (without iron doping). The highest H₂production (1736 mL) from FW occurred when Fe²⁺ concentration was equal to 50 mg/L. In addition, the process production from OW was modelled through the modified Gompertz equation. For FW, a translated Gompertz equation was used by the authors, because the initial lag-time for H₂production from FW was almost negligible.
Keywords: anaerobic digestion; biohydrogen; iron; organic waste; waste treatment.