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Novel Technologies for Enhanced Production of Ethanol: Impact of High Productivity on Process Economics

M. M. Azam, T. C. Ezeji, N. Qureshi
European chemical bulletin 2014 v.3 no.9 pp. 904-910
Saccharomyces cerevisiae, batch fermentation, calcium carbonate, calcium chloride, culture media, ethanol, ethanol production, glucose, production costs
In these studies Saccharomyces cerevisiae NRRL Y-566 was used to produce ethanol from a concentrated glucose (250-300 gL-1) solution. When fermentation media were supplemented with CaCO3 and CaCl2, ethanol concentrations, yield, and productivities were improved significantly. In control batch fermentation, the culture was able to produce 20.87 gL-1 ethanol with a productivity of 0.25 gL-1h-1 when using 100 gL-1 sugar solution in feed. When supplemented with a solution of 0.40 gL-1 CaCl2, ethanol concentration, yield, and productivity were improved to 90.0 gL-1, 0.48, and 1.25 gL-1h-1 (500% increase), respectively. The effect of CaCO3 supplementation was not as pronounced as that of CaCl2. Using these parameters, the process economics for production of ethanol was performed and it was projected that supplementation with 0.40 gL-1 CaCl2 would result in the production of ethanol for $0.91 kg-1. It was also projected that improving productivity to 37.5 gL-1h-1 using cell recycle and supplementation with CaCl2 would result in the production of ethanol for $0.70 kg-1 employing S. cerevisiae NRRL Y-566. Using Z. mobilis in membrane cell recycle reactors and application of CaCl2 can result in achieving high productivities (500-600 gL-1h-1) and reduction in ethanol production price to $0.59 kg-1.