DESALTING SYSTEM AND METHOD OF DESALTING

摘要

A desalination apparatus includes a pretreatment device (13) having a pretreatment membrane (13a) that filters suspended matters in raw water (11) with added chlorine-containing water (12), a reverse osmosis membrane device (17) having a reverse osmosis membrane (16) that removes a salt content from filtrate water (14) supplied from the pretreatment device (13) to produce permeated water (15), and a reducing-agent injection device (30) that neutralizes the added chlorine on an upstream side of the reverse osmosis membrane device (17). The reducing-agent injection device (30) extracts a part (14a) of the filtrate water (14), adds metering SBS solution (18) to the part, obtains a maximum change point (equivalence point) of the oxidation-reduction potential of a reducing agent and chlorine, obtains reducing-agent additive concentration (Csm) corresponding to the equivalence point, and supplies the SBS solution (18) corresponding to the concentration to the filtrate water (14) to thereby neutralize the chlorine.