TECHNOLOGY FOCUS - BIOTECHNOLOGY - Preferred Process: In manufacturing butanol and/or acetone, the initial pH is in the range of 5.3 to 5.7. Fermentation step is carried out without the removal of solids. The draff, spent lees, and/or pot ale are by-products of the manufacture of malt whisky. The spent grain consists of 100% malted barley. Treating and fermenting steps are carried out simultaneously. Treating and fermenting steps are carried out sequentially. The substrate is diluted to lower the concentration of free copper ions to below 15 mu M during at least the fermentation step. Draff is provided by the further steps of: grinding malted barley comprising starch to provide ground malted barley; mixing the ground malted barley with water to provide a mash comprising water and ground malted barley; hydrolyzing at least a part of the starch in the ground malted barley of the mash to provide draff comprising spent barley solids and wort comprising water and one or more carbohydrates selected from glucose and oligosaccharides of glucose; and separating the draff from the wort. The pot ale is provided by the further steps of: adding yeast to the wort; fermenting the wort to provide a wash comprising water and one or more alcohols; and distilling the wash in a copper distillation vessel to provide a low wines distillate comprising one or more alcohols and a distillation residue of pot ale. Treating of the substrate to hydrolyze it comprises hydrolyzing the substrate in the presence of water and hydrogen ions or water and hydroxide ions; hydrolyzing the substrate in the presence of an aqueous solution of sulfuric acid; or treating the substrate with one or more enzymes. The culture of butanol- and/or acetone-forming microorganisms comprises bacteria of the genus Clostridium. The fermented product further comprises one or more of the compounds selected from ethanol, carbon dioxide, hydrogen, acetate and butyrate. Malt whisky is Scotch malt whisky. The diluent comprises at least one of pot ale, water and spent lees. The spent lees is provided by the further steps of distilling the low wines distillate to provide a further low wines distillate and a further distillation residue of spent lees. EXAMPLE - No suitable example given.