製糖工業と膜分離技術

Abstract

Clarification and concentration of sugar juices and liquors in sugar factory and refinery by membrane separation technique are discussed. Ultrafiltration is superior to traditional clarification methods in purification of sugar cane and sugar beet juices. The permeation flux in the ultrafiltration is influenced by pH and temperature of both the juices, and by addition of bagasse to the cane juice. The sugar juices are partially concentrated by reverse osmosis. Polysaccharides contained in refined cane sugar are removed by ultrafiltration. Affination syrup is considerably decolorized by ultrafiltration and the ultrafiltrate is more easily decolorized with adsorbents than the original affination syrup. Final cane molasses is efficiently clarified by a self-rejecting membrane formed dinamically on a porous ceramic tube. Reverse osmosis is applicable to concentraion of sweet water or waste water contaning sugar. Waste effluent from regeneration of decolorizing ion-exchange resin in a sugar refinery is fractionated into two fractions, i.e. a salt solution (permeate) and a colored solution (retentate) through a reverse osmosis membrane with a properly low salt rejection, and the salt solution has almost the same capacity to regenerate a exhausted resin as a freshly prepared salt solution has. The economy for the ultrafiltration or reverse osmosis process is also discussed.