Hydrogen is recognized as an ideal future energy carrier for the replacement of fossil fuels. Among hydrogen production processes, mixed culture dark fermentation has been viewed as the most promising and environmental friendly. If waste/wastewaters can be used as raw materials for the production of hydrogen in such process, its overall sustainability can be even augmented. For this purpose, it is of utmost importance to select, e.g. by means of environmental pressure, the seed sludge used to start-up. The aim is to obtain a reliable method for the development of microbial anaerobic mixed comm ...