CLEANING AND RECLAMATION OF ALCOHOL SOLUTION USED FOR WASHING OR PURIFICATION OF POLYSACCHARIDE

PROBLEM TO BE SOLVED: To purify and reclaim a used alcohol solution without changing the original composition of the solution to enable the reuse of the solution and decrease the amount of industrial waste by passing an alcohol solution used in the washing or purification of polysaccharides through a separation membrane. SOLUTION: An alcohol solution used for the washing or purification of a polysaccharide is passed through a separation membrane to separate and remove impurities and unnecessary components intruded into the alcohol solution. The alcohol solution is preferably an ethanol solution having a water content of 40-90wt.%. The separation membrane is preferably a solute-separation membrane of a loose reverse osmosis membrane level resistant to ethanol and effective for inhibiting the permeation of a substance having a molecular weight of 200-4,000 in an alcohol solution. The material of the membrane is preferably polyimide, polyamide, etc. The water mixed into the alcohol solution is preferably removed by the dehydration treatment by a permeation evaporation method using a permeation evaporation membrane having selective water-permeability. The permeation evaporation membrane is e.g. polyvinyl alcohol membrane.