Method for preserving composite semipermeable membrane, preservation solution, and spiral membrane element

Abstract

Provided are a method for preserving a composite semipermeable membrane which is less likely to cause a decrease in the water permeability of the composite semipermeable membrane even in a high-temperature environment, a preservation solution used for the method, and a spiral membrane element including the preservation solution. A method for preserving a composite semipermeable membrane that allows monovalent ions to selectively permeate therethrough, the method includes using an aqueous solution containing an inorganic salt and/or an organic salt composed only of monovalent cations and monovalent anions as a preservation solution to be brought into contact with the composite semipermeable membrane.

Dependencies are inferred from the claim text.