| 摘要 |
PROBLEM TO BE SOLVED: To increase the recovery rate of a water treatment for purifying raw water using a reverse osmosis membrane apparatus by suppressing a decrease in water quality of permeated water not through complicated operation management.SOLUTION: A reverse osmosis membrane apparatus 20 including a reverse osmosis membrane which has a negatively charged skin layer using crosslinking fully aromatic polyamide on a surface, and also has a water permeation coefficient of 1.3×10to 1.7×10mmsPaand a salt removal rate of 99% or higher when a sodium chloride solution of 500 mg/L in concentration, pH 7.0, and 25°C in temperature is supplied under conditions of an operation pressure of 0.7 MPa and a recovery rate of 15% is supplied with raw water which contains silica and a hard component and has a mol ratio of 1.5 or higher of contained calcium ions to contained sodium ions through a supply path 10 to separate the raw water into permeated water and concentrated water. |
