(449f) Fed-Batch Fermentation with Gas Stripping for Economic Production of Butanol From Lignocellulosic Feedstocks

Lignocellulosic biomass is the most abundant renewable resource available for biochemicals and biofuels production. Wood pulp, corn cob and cassava bagasse, which are available as agro-industrial residues, were studied as potential feedstocks for biobutanol production. Different pretreatment and hydrolysis methods, including alkaline, acid and enzyme, were investigated to maximize the sugar yields and to study the inhibition effect on subsequent fermentation. Alkaline and acid pretreatment yielded a mixture of glucose, xylose and arabinose in the hydrolysate from wood pulp and corn cob, whereas glucose was the main component in the enzymatic hydrolysate of cassava bagasse. Using cassava bagasse enzymatic hydrolysate, 108.5 g/L ABE was produced in an immobilized-cell fibrous bed bioreactor with Clostridium beijerinckii in an integrated fed-batch fermentation, of which 76.5 g/L was butanol. No inhibition from hydrolysate was observed in the fermentation process. Inhibition was observed when using alkaline pretreated wood pulp and acid pretreated corn cob as feedstocks in the same integrated fermentation process. Detoxification was needed and activated carbon was studied for effective inhibitor removal. It was suggested that the inhibitory hydrolysates could be mixed with other substrate, such as molasses, to reduce the toxicity on cells. This paper sheds light on economic butanol production with simple lignocellulosic biomass pretreatments and reduced recovery cost.