Sulphite waste liquor

Pulp and Paper Technical Association of Canada - Standards of Sulphite Waste Liquor, C-3, Jan. 68. Viscosity of Sulphite Waste Liquor, C-4,Jan. 68. F-2, Nov. 70. Wire Screening, F-3, July 92. Alum Solutions, F-4, Jan. 68, http //WWW. paptac.ca/english/engdatsh.htm. 

Sulphite waste liquor Glucose (from starch) Wastes from fruit processing 12-2... 

Yeast, n-alkanes Bacteria, Methanol Yeast, Ethanol Fungus, Sulphite waste liquor... 

The substrate contributes least to production cost when it is a waste. See Table 4.9 -Sulphite waste liquor is the waste and contributes only 17% to total production cost... 

The most significant cost of fermentation equipment is usually the bioreactor. However, for fungal SCP processes from sulphite waste liquor, the cooling system is the most significant cost. See Table 4.13. 

The main carbon source for production of SCP is petroleum. It has been practised in many companies around the world. Other potential substrates for SCP include bagasse, citrus wastes, sulphite waste liquor from pulp and paper, molasses, animal manure, whey, starch, sewage and agricultural wastes. 

Rychtera, M., Barta, J., Fiecter, A., and Einsele, A. A. (1977). Several aspects of the yeast cultivation on sulphite waste liquors and synthetic ethanol. Process Biochem. 12(2), 26-30. Rydholm, S. A. (1965). "Pulping Processes." Wiley (Interscience), New York. 

Sulphite Waste Liquor.—One ton of pulp will produce from 2,500 to 5,000 gal. of waste liquors, the density of which will vary from 6 to 10 per cent. It is usually concentrated after neutrahzation to about 30°B6. (50 per cent solids) in multiple-effect evaporators of the vertical or rapid-circulation type, and the capacity is from 2 4 to 3J gal. per square foot, with a steam pressure of 5 lb. and a vacuum of from 27 to 28 in. The tubes will foul very quickly, on account of the large amount of calcium sulphate contained in the weak solution, and therefore evaporators are to be constructed so that tubes can readily be cleaned mechanically. 

Depending on the particular technological processes in which the water was used, industrial wastewaters differ in their character of pollution, chemical composition and physical properties. In some cases the contents of substances is so high (e.g in sulphite waste liquors, mother liquors from crystallization) that it is difficult to talk about water as such. 

Concentrated wastewaters with high BOD5 values (of the order of units of g 1, e.g. from the production of synthetic resins, extraction of caprolactam, sulphite waste liquors) must be sufficiently diluted before biological treatment. 

Both fungi and yeasts have been grown commercially on sulphite waste liquors. However, the gradual change in pulping from sulphite to Kraft processes has reduced availability to such an extent that most commercial yeast plants in North America have closed down. One commercial plant to produce 10,000 tons of fungal protein has been set up in Finland. Similarly, a process to use starch wastes is operating in Scandinavia. 

Considerable effort also is spent on developing SCP for direct human feeding. At the moment only the yeast, Candida utilis,produced on sulphite waste liquor or etheuiol, is permitted in foods at inclusion levels of less than 3%. The only protein isolate produced to date has been made from bakers yeast and approved as a food additive by FDA. 

Torula yeast Torulopsis utilis) is a hardy type of yeast that can be propagated on a variety of substrates, such as press liquor obtained during the manufacture of dried citrus pulp, molasses, sulphite waste liquor from the paper industry, saccharified wood (both hexoses and pentoses can be used), and fruit wastes such as coffee beans, apples, etc. While brewers yeast is truly a by-product food, torula yeast is cultured specifically as a foodstuff for man and animals. 

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