TECHNOLOGY FOCUS - BIOLOGY - Preferred Components: The cellulolytic and/or hemicellulolytic enzymes are produced by a microorganism belonging to Trichoderma, Aspergillus, Penicillium or Schizophyllum or anaerobic bacterial belonging to Clostridium. Preferred Method: The step (c) is carried out in the presence of microorganism consisting of Clostridium and Escherichia Coli.    TECHNOLOGY FOCUS - ORGANIC CHEMISTRY - Preferred Components: The internal flow comprising alcohols consists of ethanol, propanol, isopropanol and/or butanol provided that, when the alcohol is ethanol, it is mixed with at least one alcohol with 3, 4 or 5 carbon atoms. Preferred Method: The process comprises: performing solid/liquid separation of at least one portion of vinasse so as to recover a liquid fraction containing pentoses and performing fermentation of pentose of liquid fraction so as to provide internal flow comprising the alcohols; performing solid/liquid separation of at least one portion of effluent so as to recover a liquid fraction containing solubilized sugars and performing fermentation of solubilized sugars of the liquid fraction so as to provide the internal flow comprising alcohols; performing solid/liquid separation of at least one portion of effluent so as to recover a pulp, washing the pulp so as to recover a liquid fraction containing solubilized sugars and performing fermentation of solubilized sugars of the liquid fraction so as to provide the internal flow comprising alcohols; and performing a solid/liquid separation of at least one hydrolyzate so as to recover pulp and a liquid fraction each containing hexoses and optionally pentoses and performing fermentation of hexoses and optionally pentoses contained in the pulp and in the liquid fraction so as to provide the internal flow comprising the alcohols. The internal flow is obtained from a part of the fermented effluent. The internal flow is a liquid fraction obtained from solid/liquid separation of a portion of the fermented effluent. The internal flow is a liquid fraction obtained after washing a cake from solid/liquid separation of a portion of the effluent. The step (b) and (c) are carried out in the same reactor. The internal flow comprising alcohols is vaporized after the step (e). EXAMPLE - No suitable example given.