METHOD AND APPARATUS FOR CONCENTRATING AQUEOUS SOLUTION OF ORGANIC ACID METAL SALT

摘要

PROBLEM TO BE SOLVED: To provide a method and an apparatus for concentrating an aqueous solution of an organic acid metal salt which enable a stable operation over a long period by removing e.g. inorganic salts deposited on the membrane surface without stopping for cleaning of the membrane and give the organic metal salt obtained by concentration in a high yield, in concentrating an aqueous solution of a neutralized organic acid metal salt by using a reverse osmotic membrane.SOLUTION: A method of concentrating an aqueous solution of an organic acid metal salt is based on concentrating an aqueous solution containing an organic acid metal salt by using a reverse osmotic membrane, and the pH of the aqueous solution of the organic acid metal salt to be supplied to the reverse osmotic membrane is changed periodically in the range of 4.5-6.0.