Continuous ethanol production in biofilm reactors containing plastic composite rings and discs
- Iowa State Univ., Ames, IA (United States); and others
Biofilms are natural forms of cell immobilization in which microorganisms attach to solid supports. At ISU we have developed plastic composite-supports (50% agricultural material, and 50% polypropylene) which stimulate biofilm formation and which can supply micronutrients to the attached microorganism. These plastic supports are produced by twin-screw high temperature extrusion producing ring or discs. For continuous ethanol fermentations with Saccharomyces cerevisiae (ATCC 24859), each packed-bed bioreactors (50 ml) contained plastic composite-rings and -discs, or polypropylene rings (control) with support surface areas of 160 cm{sup 2}, and operated at 30{degrees}C. For polypropylene rings, cell-washout occurred at dilution rates of 1.9 h{sup -1} in 0.6% yeast extract medium, and at 0.48{sup -1} in {ge}0.4% ammonium sulfate medium. With plastic composite-support bioreactors, however, S. cerevisiae at a dilution rate of 1.92 h{sup -1} produced 50 g/l/h with 100% expected theoretical conversions of glucose to ethanol. Also, repeated batch fermentations were performed for 11 different composite-supports in medium with varying concentrations of yeast extract to 0% nitrogen. S. cerevisiae with plastic composite-supports whereas with polypropylene supports, ethanol production was reduced significantly. The plastic composite-support blend selected for best performance contained 40% ground soybean hulls, 5% soybean flour, 5% yeast extract, mineral salts, and 50% polypropylene. Therefore, increased productivity in low cost medium can be achieved beyond conventional fermentations by using this novel bioreactor design.
- Research Organization:
- National Renewable Energy Lab. (NREL), Golden, CO (United States)
- OSTI ID:
- 115324
- Report Number(s):
- NREL/CP-200-8098; CONF-9508104-; ON: DE95009230; TRN: 95:006736-0105
- Resource Relation:
- Conference: 2. meeting on biomass of the Americas, Portland, OR (United States), 21-24 Aug 1995; Other Information: PBD: [1995]; Related Information: Is Part Of Second biomass conference of the Americas: Energy, environment, agriculture, and industry. Proceedings; PB: 1741 p.
- Country of Publication:
- United States
- Language:
- English
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