Production of ethanol from starch by co-immobilized Zymomonas mobilis -- Glucoamylase in a fluidized-bed reactor
- Oak Ridge National Lab., TN (United States). Bioprocessing Research and Development Center
The production of ethanol from starch was studied in a fluidized-bed reactor (FBR) using co-immobilized Zymomonas mobilis and glucoamylase. The FBR was a glass column of 2.54 cm in diameter and 120 cm in length. The Z. mobilis and glucoamylase were co-immobilized within small uniform beads (1.2 to 2.5 mm diameter) of {kappa}-carrageenan. The substrate for ethanol production was a soluble starch. Light steep water was used as the complex nutrient source. The experiments were performed at 35 C and pH range 4.0 to 5.5. The substrate concentrations ranged from 40 to 185 g/L and the feed rates from 10 to 37 mL/min. Under relaxed sterility conditions, the FBR was successfully operated for a period of 22 days, during which no contamination or structural failure of the biocatalyst beads was observed. Maximum volumetric productivity of 38 g ethanol/L-h, which was 76% of the theoretical value, was obtained. Typical ethanol volumetric productivity was in the range of 15 to 20 g/L-h. The average yield was 0.51 g ethanol/g substrate consumed, which was 90% of the theoretical yield. Very low levels of glucose were observed in the reactor, indicating that starch hydrolysis was the rate-limiting step.
- Research Organization:
- Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
- Sponsoring Organization:
- USDOE Assistant Secretary for Energy Efficiency and Renewable Energy, Washington, DC (United States)
- DOE Contract Number:
- AC05-96OR22464
- OSTI ID:
- 510345
- Report Number(s):
- CONF-9705112-3; ON: DE97007704; TRN: AHC29717%%57
- Resource Relation:
- Conference: 19. symposium on biotechnology for fuels and chemicals, Colorado Springs, CO (United States), 4-8 May 1997; Other Information: PBD: [1997]
- Country of Publication:
- United States
- Language:
- English
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