Fresh Water Production Method

Abstract: The present invention provides a means for suppressing the progression of fouling of a semipermeable membrane, such as when fresh water is obtained by desalination of seawater, salt water, or the like using a membrane or when water for reuse is obtained by purification of processed wastewater, industrial effluent, or the like. This fresh water production method comprises: a membrane treatment step in which semipermeable membrane supply water is treated using a semipermeable membrane so that said water is separated into permeated water and concentrated water; and at least one of (A) a pretreatment step in which water to be treated is pretreated to obtain the semipermeable membrane supply water, (B) a cleaning step in which the semipermeable membrane is cleaned, and (C) a disinfectant addition step in which a disinfectant is added to the semipermeable membrane. If the biopolymer concentration of the semipermeable membrane supply water exceeds 75 µg C/L, or if the biopolymer concentration of the concentrated water exceeds 75 × 1/(1 - R) µg C/L, R being the recovery rate of the permeated water in the membrane treatment step, running conditions for at least one of the pretreatment step, the cleaning step, and the disinfectant addition step are added or strengthened.

Patent Information

Applicants

Inventors

Specification

Documents

Application Documents