Production of n-butanol from biodiesel derived crude glycerol using Clostridium pasteurianum immobilized on Amberlite

This paper presents accounts of research on conversion of biodiesel derived crude glycerol to n-butanol via anaerobic fermentation pathway, using immobilized Clostridium pasteurianum cells. Experiments were done to optimize the growth conditions and growth medium, viz. Reinforced Clostridial Media (RCM) and Cooked Meat Media (CMM). Out of these two media, growth was found to be faster in RCM, which was used for experiments. The cells were immobilized on a hydrophilic support Amberlite, an ion exchange resin. Varying concentration of crude glycerol as a substrate was found to have significant effect on product profile with 25 g L−1 glycerol giving maximum yield of n-butanol after 120 h. High concentration of 150 g L−1 glycerol exerted an inhibitory effect on n-butanol production with decreased 1,3-propanediol production, and absolutely no formation of ethanol. Maximum yield of ethanol and 1,3-propanediol was obtained with 5 g L−1 and 10 g L−1 crude glycerol respectively. To the best of our knowledge, this is the first report of use of the immobilized cells (immobilization of C. pasteurianum cells on Amberlite) for bioconversion of glycerol to butanol.