| 摘要 |
PURPOSE:To constantly control the concn. of a component to be eluted, by depositing the component to be eluted to the surfaces of voids of a porous body and always accumulating water of a saturated state in voids. CONSTITUTION:A film 21 of mineral components comprising carbonate or bicarbonate of Ca, Mg, K or Na is deposited to the substrate 20 of a porous body so as to reach the interior thereof. A fluid film 23 participated in water is present on the surface of a mineral material 19 in water and the elution of mineral components into water is suppressed by the diffusion resistance of the fluid film 23. However, the diffusion resistance of the fluid film 23 becomes small by a flow speed during the passage of water and mineral components become easy to diffuse from voids 22 to prevent the lowering in the concn. of mineral components in treated water.
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