Method for producing sugar solution

摘要

A method for producing a sugar solution by filtering a cellulose-derived sugar solution through one or more separation membranes selected from an ultrafiltration membrane, a nanofiltration membrane, and a reverse-osmosis membrane, wherein it is possible to effectively clean dirty separation membranes by cleaning separation membranes, which are dirty as a result of filtration, by using a cleaning fluid containing an alkaline substance and an aromatic compound, and cleaning at a temperature of 10°C or higher and less than 50°C.