Sulphite-alcohol bard

Sulphite-alcohol stillage - a liquid with a pungent odor, a strongly acid reaction p N = 1.0-1.5. Sulphite alkali contains (% by mass): 10-14% organic matter, including 7-10% lignosulfonates and 3-4% monosaccharides (mainly xylose , galactose , glucose ), volatile organic acids ( acetic and formic in a ratio of 10 : 1; their amount in sulphite liquor from coniferous wood reaches 10-15% of the sugar content, from hardwood - 30-45%), mineral acids (mainly sulfur and sulfur ), the rest is water and other impurities.

After removal of SO ₂ and some impurities, such as furfural and zymol , and adjusting the pH to 4.2-4.5 from organic substances, CSPs obtain:

• biochemical processing with enrichment with nutrient salts ( nitrogen , phosphorus , potassium ):
  • ethanol
  • polyols
  • carboxylic acids
  • solvents
  • feed yeast , etc .;
• chemical processing:
  • vanillin
  • phenols
  • aromatic acids .

By evaporation of the PRS freed from carbohydrates (usually up to a dry solids content of about 50%), the so-called sulfite-alcohol stillage concentrate (KSSB) is produced, used for tanning leather, as a binder in the manufacture of foundry molds, etc.

PRS is also a plasticizer for cement mortars and concrete. This surfactant disperses the colloidal cement paste system and thereby improves its fluidity and ductility.

For 1 ton of cellulose, 8–9 m³ of PRS is formed. 100-110 kg of yeast (or 80-100 l of ethanol and 35-45 kg of yeast) and 1.0-1.2 t of KSSB are obtained from this amount.

• Sapotnitsky S. A., Use of sulfite liquors, 2nd ed., M., 1965
• Gordon L.V., Skvortsov S.O., Lisov V.I., Technology and equipment for wood chemical production, 5th ed., M., 1988