Fresh water generating device and fresh water producing method

摘要

PROBLEM TO BE SOLVED: To enhance fresh water generation efficiency without discharging concentrated salt water or the like to outside.SOLUTION: A fresh water generation device comprises an evaporator 2 for performing evaporative concentration of salt water which is a draw solution for generating concentrated salt water and condensed water. The fresh water generation device is configured to supply the concentrated salt water from the evaporator 2 to a first chamber 3b partitioned by a positive osmosis membrane 3a, and supply dilution water having low density of sodium chloride to a second chamber 3c, and then the concentrated salt water in the first chamber 3b is diluted and its amount is increased by permeable water which has permeated the positive osmosis membrane 3a. The diluted concentrated salt water is separated into permeable water and concentrated salt water by an inverse osmosis membrane device 4, and the separated concentrated salt water is recycled to the evaporator 2 as the draw solution.