The influence of iron concentration on biohydrogen production from organic waste via anaerobic fermentation

Different micronutrients are essential for bacterial fermentative metabolism. In particular, some metallic ions, like iron, are able to affect the biological H2 production. In this study, batch tests were carried out in stirred reactors to investigate the effects of Fe2+ concentration on fermentative H2 production 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 H2 production from OW (922 mL) compared with the control (without iron doping). The highest H2 production (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 H2 production from FW was almost negligible.