%0 Journal Article
%T Optimization of Agitation and Aeration for Very High Gravity Ethanol Fermentation from Sweet Sorghum Juice by Saccharomyces cerevisiae Using an Orthogonal Array Design
%A Naulchan Khongsay
%A Lakkana Laopaiboon
%A Prasit Jaisil
%A Pattana Laopaiboon
%J Energies
%D 2012
%I MDPI AG
%R 10.3390/en5030561
%X Optimization of three parameters: agitation rate (A; 100, 200 and 300 rpm), aeration rate (B; 0.5, 1.5 and 2.5 vvm) and aeration timing (C; 2, 4 and 6 h), for ethanol production from sweet sorghum juice under very high gravity (VHG, 290 g L £¿1 of total sugar) conditions by Saccharomyces cerevisiae NP 01 was attempted using an L 9 (3 4) orthogonal array design. The fermentation was carried out at 30 ¡ãC in a 2-L bioreactor and the initial yeast cell concentration was approximately 2 ¡Á 10 7 cells mL £¿1. The results showed that the optimum condition for ethanol fermentation should be A 2 B 3 C 2 corresponding to agitation rate, 200 rpm; aeration rate, 2.5 vvm and aeration timing, 4 h. The verification experiments under the optimum condition clearly indicated that the aeration and agitation strategies improved ethanol production. The ethanol concentration ( P), productivity ( Qp) and ethanol yield ( Yp/s) were 132.82 ¡À 1.06 g L £¿1, 2.55 ¡À 0.00 g L £¿1h £¿1 and 0.50 ¡À 0.00, respectively. Under the same condition without aeration (agitation rate at 200 rpm), P and Qp were only 118.02 ¡À 1.19 g L £¿1 and 2.19 ¡À 0.04 g L £¿1h £¿1, respectively while Yp/s was not different from that under the optimum condition.
%K aeration
%K agitation
%K ethanol fermentation
%K orthogonal array design
%K Saccharomyces cerevisiae
%K very high gravity
%U http://www.mdpi.com/1996-1073/5/3/561