Stillage treatment

Barta, Z., Reczey, K., Zacchi, G., 2010. Techno-economic evaluation of stillage treatment with anaerobic digestion in a softwood-to-ethanol process. Biotechnology for Biofuels 3, 21-32. 

Historically, a classic example of an evaporation process is the production of table salt. Maple syrup has traditionally been produced by evaporation of sap. Concentration of black liquor from pulp and paper processing constitutes a large-volume present application. Evaporators are also employed in such disparate uses as desalination of seawater, nuclear fuel reprocessing, radioactive waste treatment,preparation of boiler feed waters, and production of sodium hydroxide. They are used to concentrate stillage waste in fermentation processes, waste brines, inorganic salts in fertilizer production, and rinse liquids used in metal finishing, as well as in the production of sugar, vitamin C, caustic soda, dyes, and juice concentrates, and for solvent recovery in pharmaceutical processes. 

The fermentation of sulfite waste liquor was attacked in a novel way by Nord and co-workers and is reported by Nord and Mull (93). Fusarium Uni Bolley ferments pentoses and was able to grow on sulfite liquor provided the liquor was first freed of toxic substances by lime treatment or, alternatively, by a resin. The amount of alcohol produced was small. Attempts were made to ferment with Fusarium stillage from an alcohol plant operating on wheat, and an amount of alcohol equivalent to 6-12% of that obtained from yeast fermentation was obtained. It was shown that Fusarium mycelium was not toxic to mice, which would indicate there was no objection to the use of a Fusanam-fermented stillage as feed. 

Potential applications of membrane processes in cereal production are in the treatment of stillage, in com wet milling operations, evaporation of steep water, concentration of dilute sweet waters, and in polishing of reverse osmosis permeate and evaporator overheads. Com proteins can be recovered from stillage solubles of dry milled fractions of com, grits, flour, degerminated meal, etc. by reverse osmosis. 

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