The present invention relates to a process for cleaning a solid support of a fermentation reactor for the production of alcohols by fermentation using a sugary fluid, the solid support comprising a polyurethane foam inoculated with a biomass produced by a solvent-producing strain belonging to the genus Clostridium, the process comprising placing the solid support in contact with a fluid originating from the fermentation must enriched in alcohol and/or acetone and/or an aqueous solution at basic pH.