| Abstract |
| This study was motivated to produce healthful and good-tasting water using Jeju groundwater which contains useful mineral ions. The K-index was applied to assess the quality of treated water. The original value of K-index of raw groundwater was -13.3 and nano-filtration process was applied to increase it up to 2.0 with high recovery ratio. The process was tested while circulating the concentrate to a raw water tank for the purpose of increasing mineral concentrations such as calcium, magnesium and vanadium. Among four kinds of membranes tested with different pressure conditions, the membrane with the lower salt rejection ratio at lower pressure condition was favourable for that purpose. The recovery ratio of produced water increased up to 87.5% while circulating the concentrate and water qualities were analyzed at several recovery ratio points. And a mathematical model was used to simulate the higher recovery conditions and then water qualities. When a NE4040-40 membrane was used at 2 bar of pressure, ion concentrations of the concentrate water were calculated by the model. When the system reached 99% recovery, the concentrated water was 20 times diluted with pure water. Then the K-index value reached 2.0 applying the dilution factor. |
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| Key Words |
| Nano filtration, Mineral control, Hardness, K-index, O-index, Nano filtration modeling |
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