Cereal Chem 65:345-348   |  VIEW ARTICLE

Recovery of Stillage Soluble Solids from Corn and Dry-Milled Corn Fractions by High-Pressure Reverse Osmosis and Ultrafiltration.

Y. V. Wu. Copyright 1988 by the American Association of Cereal Chemists, Inc. 

High-pressure reverse osmosis (RO) combined with ultrafiltration (UF) was used to separate stillage solubles from corn and dry-milled corn fractions into small volumes of concentrated solutions and large volumes of permeates suitable for reuse. The UF permeate at 680 kPa (100 psi) contained 23-60% of total nitrogen and 38-65% of total solids of the stillage solubles. The UF permeate was used as the feed solution for RO. The RO permeate at 6,800 kPa (1,000 psi) contained 0.32-1.3% of the total nitrogen, 0.13-0.41% of total solids and 77-86% of total volume of the UF permeate. The percentage of nitrogen and solids from stillage solubles that can be economically recovered by combined UF and RO at 6,800 kPa (assuming only the amount of nitrogen and solids in the RO permeate is discarded) is 99.6-99.9% and 99.8-99.9%, respectively. Conductivity of the RO permeate at 6,800 kPa was lower than that of tap water. UF and high- pressure RO methods developed for stillage solubles from corn and dry-milled corn fractions may encourage increased use of distillers' grains from corn and corn fractions while reducing the total cost of the alcohol process.