Operation method of raw water compartment and water treatment device

Abstract

This invention provides a raw water spacer that can form a membrane module that inhibits the adhesion of cationic substances to the surface of a membrane, and a method for operating a water treatment apparatus equipped with the membrane module. The raw water spacer includes a plurality of first linear bodies and a plurality of second linear bodies forming a mesh-like planar structure. The plurality of first linear bodies and the plurality of second linear bodies are composed of a composite material formed by incorporating carbon nanotubes into a substrate resin, wherein each 100 parts by weight of the composite material contains 1 to 7 parts by weight of carbon nanotubes. The surface roughness of the plurality of first linear bodies and the plurality of second linear bodies is configured such that the arithmetic mean height Sa, as specified in ISO 25178, reaches 0.2 μm to 0.5 μm.

Claims

1. A raw water spacer, disposed within a membrane separation module in a water treatment apparatus, and ensuring a flow path for the raw water between two membrane separation membranes, wherein the water treatment apparatus supplies the raw water containing the target components and water to the membrane separation module, causing it to separate into permeate water that passes through the membrane separation module and concentrated water that does not pass through the membrane separation module, wherein the membrane separation module is disposed within the membrane separation module, and the raw water spacer comprises: A plurality of first linear bodies arranged side by side; A plurality of second linear bodies arranged side-by-side, the plurality of first linear bodies and the plurality of second linear bodies being arranged in intersecting directions to form a mesh-like surface, wherein the plurality of first linear bodies and the plurality of second linear bodies are configured such that, when the raw water spacer is positioned between two separation membranes, the plurality of first linear bodies contact one of the separation membranes, and the plurality of second linear bodies are interposed between the plurality of first linear bodies and the other separation membrane to ensure the gaps forming the flow path of the raw water, and the A plurality of second linear bodies contact another separation membrane, with a plurality of first linear bodies interposed between the plurality of second linear bodies and one of the separation membranes to ensure the gap forming the flow path of the raw water. The plurality of first linear bodies and the plurality of second linear bodies are composed of a composite material formed by incorporating carbon nanotubes into the substrate resin. Each 100 parts by weight of the composite material contains 1 to 7 parts by weight of carbon nanotubes. The surface roughness of the plurality of first linear bodies and the plurality of second linear bodies is configured such that the arithmetic mean height Sa, as specified in ISO 25178, reaches 0.2 μm to 0.5 μm.

2. As in request item 1, the raw water spacer, wherein, The composite material is as follows: after the base resin is added to the composite material, the concentration of the carbon nanotubes in the composite material is diluted to 100 times, and the diluted material is molded into a molded article with a thickness of 0.3 mm. In the image of the surface of the molded article, three 2 mm × 2 mm fields of view are randomly selected, and when each field of view is observed, the number of carbon nanotubes with a particle area of ​​25 μm2 or more but less than 100 μm2 observed in each field of view is less than 50 on average at the three locations, and the number of carbon nanotubes with a particle area of ​​100 μm2 or more but less than 20000 μm2 observed in each field of view is less than 10 on average at the three locations.

3. As in request item 1 or 2, the raw water spacer, wherein, The quadrilateral grid formed by the first linear body and the second linear body is configured such that the distance between the diagonal directions of the quadrilateral is 4.0 mm to 5.0 mm.

4. A method for operating a water treatment device, comprising passing raw water containing the target component and water to a separation membrane module, thereby separating the raw water into permeate water that passes through the separation membrane and concentrated water that does not pass through the separation membrane, wherein the separation membrane is disposed inside the separation membrane module, wherein... The membrane module internally includes a raw water spacer for ensuring the flow path of the raw water between two membranes. The raw water spacer includes a plurality of first linear bodies arranged side-by-side and a plurality of second linear bodies arranged side-by-side. The plurality of first and second linear bodies are arranged in a cross-shaped direction and form a mesh-like surface. The plurality of first and second linear bodies are configured such that, when the raw water spacer is positioned between the two membranes, the plurality of first linear bodies contact one of the membranes, and there is a gap between the plurality of first linear bodies and the other membrane. A plurality of second linear bodies are interposed therein to ensure the gap forming the flow path of the raw water, and the plurality of second linear bodies contact another separation membrane. A plurality of first linear bodies are interposed between the plurality of second linear bodies and one of the separation membranes to ensure the gap forming the flow path of the raw water. The plurality of first linear bodies and the plurality of second linear bodies are composed of a composite material formed by incorporating carbon nanotubes in the base resin. Each 100 parts by weight of the composite material contains 1 to 7 parts by weight of carbon nanotubes. The surface roughness of the plurality of first linear bodies and the plurality of second linear bodies is configured such that the arithmetic mean height Sa, as specified in ISO 25178, reaches 0.2 μm to 0.5 μm.

5. The method of operating the water treatment apparatus as claimed in claim 4, wherein, compared to the control raw water spacer, when the solute in the raw water is NaCl, the mass transfer coefficient of each of the two separation membranes disposed on opposite sides of the control raw water spacer, at a linear velocity of 0.02 m / s to 0.14 m / s, is 1.3 to 2.4 times that of the control raw water spacer. The control raw water spacer uses the substrate resin that is not fitted with the carbon nanotube to replace the composite material, and otherwise has the same structure as the raw water spacer.

6. The operation method of the water treatment device as requested in item 4 or 5, wherein, The raw water contains at least one cationic substance selected from cationic proteins and cationic surfactants, which is the component to be separated.

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