Acetone-Butanol Fermentation of Lignocellulosic Hydrolysates for the Butanol Production

It is known that the use of lignocellulosic hydrolysates reduces the production cost of biofuel such as biobutanol and bioethanol. But for the most successful application of the hydrolysates for the biofuel production, it is necessary to apply an inexpensive and effective detoxification method and to use of cost-effective growth factors. In the present study, we evaluated the use of an acid hydrolysate of spruce and an enzymatic hydrolysate of miscanthus cellulose for the biobutanol production. To remove inhibitors from the hydrolysates, we applied the traditional physicochemical method with overliming and the biodetoxification method based on the use of the specially adapted activated sludge. Calcium hydroxide (150 g/L) was used for the neutralization. The biological method of detoxification of lignocellulosic hydrolysates was carried out under non-sterile conditions at room temperature by the specially adapted activated sludge of the urban wastewater treatment plants. The acetone-butanol fermentation was carried out by a strain of bacteria Clostridium acetobutylicum ATCC 824. The treatment by overliming removed 84-85 % and 83-86% of 5-hydroxymethylfurfural (5-HMF) and furfural from the hydrolysates respectively. Using the method of biodetoxification the content of furfural decreased by 98% and concentration of 5-HMF - by 97-99%. In the present study as an inexpensive source of growth substances for the fermentation of the hydrolysates it has been suggested to use decantate of the brewer's spent grain. The obtained results showed that the brewer's spent grain can be used in the biofuel production as efficiently as the synthetic growth substances.