TY - JOUR
T1 - Ethanol production from corn starch in a fluidized-bed bioreactor
AU - Krishnan, Mahesh S.
AU - Nghiem, Nhuan P.
AU - Davison, Brian H.
PY - 1999
Y1 - 1999
N2 - The production of ethanol from industrial dry-milled corn starch was studied in a laboratory-scale fluidized-bed bioreactor using immobilized biocatalysts. Saccharification and fermentation were carried out either simultaneously or separately. Simultaneous saccharification and fermentation (SSF) experiments were performed using small, uniform κ-carrageenan beads (1.5-2.5 mm in diameter) of co-immobilized glucoamylase and Zymomonas mobilis. Dextrin feeds obtained by the hydrolysis of 15% dry-milled corn starch were pumped through the bioreactor at residence times of 1.5-4 h. Single-pass conversion of dextrins ranged from 54-89%, and ethanol concentrations of 23-36 g/L were obtained at volumetric productivities of 9- 15 g/L-h. Very low levels of glucose were observed in the reactor, indicating that saccharification was the rate-limiting step. In separate hydrolysis and fermentation (SHF) experiments, dextrin feed solutions of 150-160 g/L were first pumped through an immobilized-glucoamylase packed column. At 55°C and a residence time of 1 h, greater than 95% conversion was obtained, giving product streams of 162-172 g glucose/L. These streams were then pumped through the fluidized-bed bioreactor containing immobilized Z. mobilis. At a residence time of 2 h, 94% conversion and ethanol concentration of 70 g/L were achieved, resulting in an overall process productivity of 23 g/L-h. At residence times of 1.5 and 1 h, conversions of 75 and 76%, ethanol concentrations of 49 and 47 g/L, and overall process productivities of 19 and 25 g/L-h, respectively, were achieved.
AB - The production of ethanol from industrial dry-milled corn starch was studied in a laboratory-scale fluidized-bed bioreactor using immobilized biocatalysts. Saccharification and fermentation were carried out either simultaneously or separately. Simultaneous saccharification and fermentation (SSF) experiments were performed using small, uniform κ-carrageenan beads (1.5-2.5 mm in diameter) of co-immobilized glucoamylase and Zymomonas mobilis. Dextrin feeds obtained by the hydrolysis of 15% dry-milled corn starch were pumped through the bioreactor at residence times of 1.5-4 h. Single-pass conversion of dextrins ranged from 54-89%, and ethanol concentrations of 23-36 g/L were obtained at volumetric productivities of 9- 15 g/L-h. Very low levels of glucose were observed in the reactor, indicating that saccharification was the rate-limiting step. In separate hydrolysis and fermentation (SHF) experiments, dextrin feed solutions of 150-160 g/L were first pumped through an immobilized-glucoamylase packed column. At 55°C and a residence time of 1 h, greater than 95% conversion was obtained, giving product streams of 162-172 g glucose/L. These streams were then pumped through the fluidized-bed bioreactor containing immobilized Z. mobilis. At a residence time of 2 h, 94% conversion and ethanol concentration of 70 g/L were achieved, resulting in an overall process productivity of 23 g/L-h. At residence times of 1.5 and 1 h, conversions of 75 and 76%, ethanol concentrations of 49 and 47 g/L, and overall process productivities of 19 and 25 g/L-h, respectively, were achieved.
KW - Dry-milled corn starch
KW - Ethanol
KW - Fluidized- bed reactor
KW - Zymomonas mobilis glucoamylase
UR - http://www.scopus.com/inward/record.url?scp=0033002945&partnerID=8YFLogxK
U2 - 10.1007/978-1-4612-1604-9_34
DO - 10.1007/978-1-4612-1604-9_34
M3 - Article
AN - SCOPUS:0033002945
SN - 0273-2289
VL - 77-79
SP - 359
EP - 372
JO - Applied Biochemistry and Biotechnology
JF - Applied Biochemistry and Biotechnology
ER -