Fermentation sulfite spent liquors

In principle, the same carbohydrates and their degradation products formed after hydrolysis of wood can be recovered from sulfite spent liquors. However, this requires complicated and expensive separation techniques. The industrial use of sulfite spent liquor components is mainly limited to fermentation processes. The most common product is ethyl alcohol which is produced from hexose sugars by yeast (Saccharomyces cerevisae) and separated from the mixture by distillation. Even the carbon dioxide formed in the process can be recovered. Other fermentation products, including acetone, n-butanol, and lactic acid, can be produced by certain microorganisms. Because some contaminants, for example, sulfur dioxide, inhibit the growth of the yeast, they must be removed from the liquor prior to the fermentation. 

Fermentation methods have traditionally played a dominant role in the industrial processing of the carbohydrate fraction of sulfite spent liquors and have also served as an effective way to reduce the pollution load from the mill. Hence, liquors have mainly been used for producing ethanol and single-ceU protein although this kind of... 

The fifth paper, "A Separative Bioreactor Direct Product Capture and pH Control," presented by Seth Snyder of the Argonne National Laboratory, reviewed development and performance of a novel bioreactor incorporating electrodeionization to simultaneously produce and separate products from both enzymatic and microbially mediated reactions. The sixth paper, " Optimization of Xylose Fermentation in Spent Sulfite Liquor by Saccharomyces cerevisiae 259ST," presented by Steven Helle of the University of British Columbia, provided an overview of an approach to fermentation optimization utilized to identify key process variables limiting use of the SSL for commercial ethanol production. 

Two different strains of Saccharomyces cerevisiae were used CBS 8066 (Centralbureau voor Schimmelcultures, Delft, The Netherlands) and TMB 3000 (Division of Applied Microbiology, Lund University, Sweden). TMB 3000 is a strain originally isolated from spent sulfite liquor, and therefore it has a high tolerance to inhibitors. The strains were maintained on agar plates (20 g/L of agar, 20 g/L of soya peptone, 20 g/L of glucose, and 10 g/L of yeast extract). Before the fermentations, inoculum cultures were grown in 250-mL conical E-flasks. The flasks were placed in a shaker bath (30°C, 140 rpm) for 24 h. 

Data of Nigam, 2001, for fermentations on spent sulfite liquor. 

Industrial scale continuous fermentations on rotoevaporated spent sulfite liquor (hardwood pulping, y softwood pulping). 

MatedLaJLs. Kraft lignin samples were obtained from WESTVACO Corp., Charleston, South Carolina they were commercial preparations traded under the name INDULIN-AT. Lignin sulfonate preparations were procured from GEORGIA PACIFIC Corp., Bellingham, Washington their commercial name is LIGNOSITE (spray-dried from fermented calcium spent sulfite liquor). 

Fermentation Kinetics for Xylitol Prodnction by a Pichia st itis D-Xylulokinase Mutant Previously Grown in Spent Sulfite Liquor... 

Chem. Descrip. Calcium lignosulfonate (fermented spent sulfite liquor)... 

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