Effective pretreatment alternatives for the production of ethanol from hemicellulosic hardwood hydrolyzates
Pretreatment and nutrient additions are required for reliable and acceptable ethanol production from acid-catalyzed hemicellulosic hardwood hydrolyzates by the yeast Pachysolen tannophilus. Neutralization of heated hydrolyzate, sulfite additions, and overliming (raising the pH to 10 with Ca(OH)/sub 2/ and then lowering the pH for conversion) alone and in various combinations were evaluated for desirable effects on ethanol production. Individual pretreatments were not as effective as pretreatment combinations. Overliming of heated hydrolyzate with the addition of sulfite was the most effective pretreatment combination, but other combinations were nearly as good. Sufficient sulfite can substitute for either heat or overliming. Both heat and overliming reduce the amount of sulfite required as a pretreatment. Excess sulfite results in the inhibition of ethanol production. The choice of a pretreatment scheme will depend on the overall process design and the consideration of pretreatment costs in relation to improved yield. Sulfite treatment was effective at different stages of overliming and sulfuric acid was suitable for pH adjustment. The reason for pretreatment improvement of conversion requires further study. Besides hydrolyzate pretreatment, nutrient additions are also important for ethanol production. Yeast extract, urea, and phosphate had tentatively been identified as useful nutrient supplements. While P. tannophilus has a phosphate requirement in hydrolyzate, yeast extract and urea may be adequate nutrient additions because sufficient phosphate but insufficient nitrogen are supplied from the yeast extract. Conversion was reduced without nutrient additions or with either urea of phosphate alone. Varying the concentration of yeast extract at a fixed level of urea and phosphate reduced ethanol production at high levels of yeast extract, perhaps because of nutrient imbalances. 16 refs., 7 figs.
- Research Organization:
- Tennessee Valley Authority, Muscle Shoals, AL (USA). Div. of Chemical Development
- OSTI ID:
- 6959296
- Report Number(s):
- TVA/PUB-87/4; CONF-850104-10; ON: DE87900336
- Resource Relation:
- Conference: 9. annual symposium on energy from biomass and wastes, Lake Buena Vista, FL, USA, 28 Jan 1985
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
ETHANOL
YIELDS
WOOD
ACID HYDROLYSIS
FERMENTATION
HEMICELLULOSE
PH VALUE
TEMPERATURE DEPENDENCE
ALCOHOLS
BIOCONVERSION
CARBOHYDRATES
CHEMICAL REACTIONS
DECOMPOSITION
HYDROLYSIS
HYDROXY COMPOUNDS
LYSIS
ORGANIC COMPOUNDS
POLYSACCHARIDES
SACCHARIDES
SOLVOLYSIS
090222* - Alcohol Fuels- Preparation from Wastes or Biomass- (1976-1989)