| 1. |
- Axelsson, Anders, et al.
(författare)
-
Determination of effective diffusion coefficients in calcium alginate gel plates with varying yeast cell content
- 1988
-
Ingår i: Applied Biochemistry and Biotechnology. - 1559-0291. ; 18, s. 231-250
-
Tidskriftsartikel (refereegranskat)abstract
- Effective diffusion coefficients (De) have been determined for lactose, glucose, galactose, and ethanol in calcium alginate gel with varying yeast cell concentration. The measurements have been performed in a diffusion cell, and the results evaluated with the quasisteady-state method. An ultrasonic meter was used for gel thickness determination with an accuracy of 1.5% and a new method for the reproducible preparation of gel plates was developed. It was found thatD e in pure alginate gel decreased to about 90% of the diffusivity in water and did not vary with alginate concentration.D e decreased considerably with increasing yeast cell concentration. For the solutes studied, the effective diffusion coefficient can be estimated according to the equationD e =D eo (1 - ϕ)/[1+(ϕ/2)], whereD eo is the effective diffusivity in pure gel and ϕ is the volume fraction of yeast cells.
|
|
| 2. |
- Axelsson, Anders
(författare)
-
Experimental studies of immobilized-yeast, packed-bed reactors with reduced CO2 entrapment
- 1988
-
Ingår i: Applied Biochemistry and Biotechnology. - 1559-0291. ; 18, s. 91-109
-
Tidskriftsartikel (refereegranskat)abstract
- A horizontal packed-bed reactor with baffles (HPBR) and a continuously stirred tank reactor with intermittent paddle agitation have been shown to considerably reduce the CO2 entrapment when glucose is fermented with immobilized baker’s yeast in calcium alginate beads. Using high cell contents in the gel resulted in internal mass transfer hindrance. The highest productivity was obtained with the HPBR giving 29 g EtOH/Lh at an ethanol yield of 90%. The substrate used was 100 g/L glucose. Fermentation of lactose and deproteinized whey by coimmobilized baker’s yeast and |3-galactosidase resulted in much lower productivity-about 5 g EtOH/L.h because of the slow fermentation of galactose.
|
|
| 3. |
|
|
| 4. |
- Zacchi, Guido, et al.
(författare)
-
Economic evaluation of preconcentration in production of ethanol from dilute sugar solutions
- 1989
-
Ingår i: Biotechnology and Bioengineering. - : Wiley. - 1097-0290 .- 0006-3592. ; 34:2, s. 223-233
-
Tidskriftsartikel (refereegranskat)abstract
- The economic feasibility of preconcentrating dilute sugar solutions prior to fermentation is investigated. Two methods, evaporation and reverse osmosis, are compared. A computer program to determine the optimal preconcentration conditions for glucose solutions of 1.5–16 wt% has been developed. It was used to compute the fractional cost for labor and maintenance, preconcentration, fermentation, and distillation. Preconcentration with evaporation resulted in a higher total cost, compared with no preconcentration, for all cases studied, although a six-effect unit was used. Reverse osmosis was found to be economically feasible for preconcentration to about 5–10 wt % depending on the concentration of the feed.
|
|
