Defoaming treatment device for organic-matter-containing water

Abstract

To provide a defoaming treatment device for organic matter-containing water capable of removing, at a high bubble-removing ratio, air bubbles from the organic matter-containing water.SOLUTION: In the present invention, raw water within a treated water collection part 1 is supplied, via a raw water inflow pipe 2, to a liquid phase chamber within a defoaming treatment device 3 for organic matter-containing water. An interior of the defoaming treatment device 3 is partitioned into the liquid phase chamber 5 and a gas phase chamber 6 by a membrane 4. Bubbles in the raw water are transmitted through the membrane 4 and moved into the gas phase chamber 6 while the raw water flows in the liquid phase chamber 4, and the bubbles in the raw water are removed. The treated water from which the air bubbles are removed is taken out via a treated water pipe 7. A porous membrane having a pore diameter of 0.1 to 2 μm is used as the membrane 4.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a defoaming treatment device for organic-containing water, and more particularly to a defoaming treatment device for organic-containing water that is suitable for use in a water reclamation system in a microgravity environment. [Background technology]

[0002] In closed spaces with microgravity environments such as space stations, it is important to reclaim recovered water, but because buoyancy does not work in a microgravity environment, the recovered water contains many air bubbles. Although it is possible to remove about 90% of the air bubbles using a centrifuge, in the case of a water reclamation system that is required to reclaim drinking water at a high recovery rate, it is necessary to use wastewater containing organic matter and no air bubbles as raw water.

[0003] Patent Document 1 describes a bubble separator using a degassing membrane as a degassing treatment device for organic-containing water. Patent Document 1 states that a porous membrane made of fluororesin or polypropylene is suitable as the degassing membrane. Generally, the pore size of porous membranes made of fluororesin or polypropylene is about 10 to 50 nm.

[0004] Patent Document 2 describes degassing boiler water using a degassing membrane module equipped with hollow fiber membranes having a skin layer. The skin layer is a dense layer that does not have pores large enough to be visible with a scanning electron microscope (Patent Document 2, paragraphs 0034 to 00035). [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Publication No. 2023-73007 [Patent Document 2] Japanese Patent Publication No. 2022-144162 Summary of the Invention [Problem to be solved by the invention]

[0006] When organic matter-containing water is degassed using a degassing membrane, the pores (pore diameter approximately 30 nm) become clogged in a short period of time, resulting in a decrease in the bubble removal rate. Even if a degassing membrane with clogged pores is cleaned using the manufacturer's recommended method (IPA + acid + alkali cleaning), its performance will not be restored, and the degassing membrane must be replaced. While it is possible to extend the membrane's lifespan by increasing its surface area, this increases the size of the degassing membrane module. Furthermore, evaporation from the pores can reduce the recovery rate of treated water.

[0007] An object of the present invention is to provide a defoaming treatment apparatus for organic-substance-containing water that can remove bubbles from organic-substance-containing water at a high defoaming rate. [Means for solving the problem]

[0008] The present invention provides the following.

[0009] [1] A defoaming treatment device for organic-containing water having a membrane for removing bubbles from organic-containing water, and a liquid phase chamber and a gas phase chamber separated by the membrane, The defoaming treatment device for organic matter-containing water is characterized in that the membrane is a hydrophobic porous membrane having pores of 0.1 to 2 μm.

[0010] [2] A defoaming treatment apparatus for organic-containing water having a membrane for removing bubbles from organic-containing water, and a liquid phase chamber and a gas phase chamber separated by the membrane, The defoaming treatment device for organic matter-containing water is characterized in that the membrane is a hydrophobic membrane having a skin layer.

[0011] [3] The defoaming treatment device for organic matter-containing water according to [2], wherein the hydrophobic membrane having a skin layer is a hollow fiber membrane.

[0012] [4] The hollow fiber membrane is disposed in a hollow fiber membrane arrangement chamber of a vessel, and a water collection pipe is installed in the vessel; The defoaming treatment device for organic matter-containing water according to [3], characterized in that the water collection pipe is provided with a slit. [Effects of the Invention]

[0013] The defoaming treatment device for organic-containing water of the first invention has a liquid phase chamber and a gas phase chamber separated by a hydrophobic porous membrane having pores of 0.1 to 2 μm. The defoaming treatment device for organic-containing water of the second invention has a liquid phase chamber and a gas phase chamber separated by a hydrophobic membrane having a skin layer. In either defoaming treatment device for organic-containing water, the liquid to be treated is passed through the liquid phase chamber to remove bubbles.

[0014] The defoaming treatment device for organic matter-containing water of the first invention can remove bubbles with a small membrane area, contributing to miniaturization. In addition, the defoaming treatment device for organic matter-containing water of the first invention has a long life because the membrane pore size is large and the rate of clogging by organic matter is low.

[0015] The defoaming treatment device for organic matter-containing water according to the first aspect of the present invention requires only a small pressure on the liquid phase side, and therefore can be operated at low pressure, which has the effect of saving power consumption for pumps and the like.

[0016] The skin layer of the membrane of the defoaming treatment device for organic matter-containing water of the second invention has a dense structure without pores, so clogging does not occur and the device has a significantly long life.

[0017] Generally, hydrophobic membranes with a skin layer do not have pores and therefore do not have the bubble removal effect of pores. Therefore, compared to porous membranes, their bubble removal performance per membrane area is inferior, requiring a larger membrane area, resulting in a larger device. However, in the defoaming treatment device for organic matter-containing water of the second invention, by providing a collection pipe with slits, sufficient time for bubbles in the water to come into contact with the hollow fibers can be ensured, enabling sufficient bubble removal even with the same membrane area as before.

[0018] The skin layer of the membrane of the degassing treatment device for organic matter-containing water of the second invention has a structure without fine pores, which suppresses evaporation from the liquid phase chamber, improving the water recovery rate and making it possible to achieve a water recovery rate of 99.9% or more. [Brief explanation of the drawings]

[0019] [Figure 1] 1 is a schematic diagram of a defoaming treatment device for organic matter-containing water for explaining an embodiment. [Figure 2] 1 is a graph showing the results of Example 1. [Figure 3] 1 is a graph showing the results of Example 2. [Figure 4] 1 is a graph showing the results of Comparative Example 1. DETAILED DESCRIPTION OF THE INVENTION

[0020] An embodiment of the present invention will be described in detail below with reference to FIG.

[0021] In Figure 1, water to be treated (raw water) consisting of organic matter-containing water in a water collection section 1 is supplied to a liquid phase chamber in a defoaming treatment device 3 for organic matter-containing water via a raw water inlet pipe 2. The interior of the defoaming treatment device 3 is partitioned by a membrane 4 into a liquid phase chamber 5 and a gas phase chamber 6. As the raw water flows through the liquid phase chamber 4, air bubbles in the raw water permeate the membrane 4 and move into the gas phase chamber 6, where they are removed. The treated water from which the air bubbles have been removed is taken out via a treated water pipe 7.

[0022] In the first invention, a porous membrane with a pore size of 0.1 to 2 μm, preferably 0.5 to 1.5 μm, is used as the membrane 4. In the first invention, the large pore size of the membrane reduces the rate of clogging by organic matter and provides a long service life, but a pore size that is too large is undesirable because it increases the amount of water that permeates the membrane as it is degassed. In the first invention, the pressure difference between the gas phase chamber 6 and the liquid phase chamber 5 of the degassing membrane may be small, and the pressure in the liquid phase chamber 4 may be 2 MPa or less, particularly about 0 to 20 kPa. The gas phase chamber 6 may be depressurized to a negative pressure or may be at normal pressure.

[0023] The membrane area is preferably set so that the gas permeation flux per unit area is 0.1 to 200 m / min, particularly 1 to 100 m / min. The membrane area here refers to the area on the raw water supply side when the membrane is considered to be flat, regardless of the pore size of the membrane.

[0024] In the first aspect of the present invention, the membrane is preferably a flat membrane or a hollow fiber membrane. In the case of a hollow fiber membrane, it is preferably an internal pressure type in which the water to be treated flows inside the hollow fiber to facilitate contact between the membrane and air bubbles.

[0025] The gas-liquid separator SEP-200 (manufactured by Zaiput Flow Technologies) can be used as the housing of the defoaming treatment device for organic matter-containing water of the first invention. By installing a hydrophobic membrane with pores of 1 μm or less in the SEP-200, a long-life defoaming treatment becomes possible.

[0026] In the second invention, a membrane having a skin layer is used as the membrane 4. The membrane having a skin layer is preferably a hollow fiber membrane. The hollow fiber membrane having a skin layer can be used in either an internal pressure type or an external pressure type, as long as the skin layer comes into contact with the liquid in the liquid phase chamber.

[0027] The membrane area is preferably set so that the gas permeation flux per unit membrane area is 0.01 to 2 m / min, particularly 0.1 to 1 m / min. The membrane area here refers to the area of ​​the raw water supply side of the membrane when the membrane is considered to be flat, without taking into account the pores in the membrane.

[0028] As the degassing treatment device of the second invention using hollow fiber membranes having a skin layer, a degassing membrane module G923 (manufactured by 3M) can be used.

[0029] The degassing membrane module G923 is a pressure-resistant vessel in which hollow fiber membranes are arranged in the longitudinal direction of the vessel. The vessel is divided into a hollow fiber membrane chamber and a gas outflow chamber by a partition wall made of potting material arranged at one end of the vessel in the longitudinal direction. A raw water inlet is provided on the side of the vessel. Raw water flows into the hollow fiber membrane chamber through this raw water inlet.

[0030] A number of hollow fibers are arranged in the hollow fiber membrane arrangement chamber in the longitudinal direction of the vessel. One end of each hollow fiber membrane is sealed, and the other end is held by the partition wall made of potting material. The inside of the hollow fiber membrane is in communication with the gas outflow chamber.

[0031] A water collection pipe is arranged at the axial center of the hollow fiber membrane chamber. One end of the water collection pipe is sealed. The other end of the water collection pipe penetrates the partition wall and the vessel end plate made of potting material and extends outside the vessel.

[0032] A large number of slits are provided on the outer peripheral surface of the portion of the water collection pipe that is present in the hollow fiber membrane chamber. The slit width is preferably about 1 to 5 mm. The slit length is preferably about 1 to 5 mm and is equally spaced. The opening ratio of the water collection pipe (opening area of ​​all slits / area of ​​the outer peripheral surface of the water collection pipe) is preferably about 20 to 50%.

[0033] The raw water supplied to the hollow fiber membrane chamber comes into contact with the hollow fiber membrane to be degassed, and then flows through the slit into the water collection pipe. The air bubbles permeate the hollow fiber membrane and then flow out into the gas outflow chamber.

[0034] This degassing membrane module G923 ensures sufficient contact time between the air bubbles and the hollow fiber membrane (with a skin layer), making degassing processing possible, and even a small module (e.g., φ60 mm x L140 mm) can sufficiently remove air bubbles.

[0035] In the defoaming treatment device for organic matter-containing water of the second invention, which uses hollow fiber membranes having a skin layer, the pressure on the liquid phase side is preferably 130 kPa or more, particularly about 130 to 200 kPa.

[0036] The thickness of the skin layer is preferably 0.1 to 10 μm, and particularly preferably 1 to 2 μm. The skin layer must be in contact with the liquid phase. When the skin layer is located on the outside of the hollow fiber, the outside of the hollow fiber is the liquid phase, and when the skin layer is located on the inside of the hollow fiber, the liquid phase is the inside of the hollow fiber.

[0037] In the present invention, the organic substance-containing water may be water containing ethanol, acetic acid, or a silane-based organic substance and having a TOC of 0.5 to 1000 mg / L. A TOC of about 100 to 200 mg / L is particularly preferable. Specifically, condensed water from a temperature and humidity control device or the like may be used. The bubble content in this organic substance-containing water is usually about 10 to 20 vol%. [Example]

[0038] The present invention will be described in more detail below with reference to examples and comparative examples.

[0039] <Raw water> In the following Examples 1 and 2 and Comparative Example 1, raw water containing 60 mg / L of ethanol, 20 mg / L of acetic acid, and 20 mg / L of silane-based organic matter-Si, with a TOC of 180 mg / L and a bubble content of 10 vol% (a test liquid simulating condensed water generated on the International Space Station) was subjected to a degassing treatment.

[0040] [Example 1] A hydrophobic porous membrane (manufactured by Zaiput Flow Technologies) having pores with a pore size of 1.0 μm was attached to a gas-liquid separator SEP-200 (manufactured by Zaiput Flow Technologies) to constitute a degassing treatment device for organic matter-containing water according to the first invention.

[0041] <Experiment and Results> This defoaming treatment device was operated with a raw water flow rate of 230 mL / min and a liquid phase pressure of 20 kPa. The gas phase chamber was at normal pressure. As a result, as shown in Figure 2, a total of 4,800 L of foam could be defoamed under 600 hours of contact with the treated liquid, including system starts and stops. However, since the foam removal rate began to decrease when treating volumes of 4,800 L or more, it is presumed that membrane clogging progressed when treating volumes of 4,800 L or more.

[0042] [Example 2] A degassing treatment device for organic matter-containing water according to the second invention was constructed by installing 2,000 hydrophobic porous membranes (manufactured by 3M) having a skin layer as hollow fibers in a degassing membrane module G923 (manufactured by 3M). The slit width was 1 mm, the slit length was 1 mm, and the opening ratio of the water collection pipe (opening area of ​​all slits / area of ​​the outer surface of the water collection pipe) was 50%.

[0043] Raw water was supplied to the hollow fiber membrane chamber at a flow rate of 230 mL / min and a liquid phase pressure of 130 kPa. The gas outflow chamber was at normal pressure.

[0044] As a result, as shown in Figure 3, it was possible to defoam a total of more than 18,000 L of liquid under 2,400 hours of contact with the treated liquid, including system starts and stops. During this time, the defoaming rate was maintained at 100%, and no clogging of the membrane occurred.

[0045] [Comparative Example 1] The degassing treatment was carried out under the same conditions as in Example 2, except that a porous hollow fiber membrane G420 (manufactured by 3M, pore size 30 nm) was used as the hollow fiber membrane.

[0046] As a result, as shown in Figure 4, a decrease in the defoaming rate was observed when a total of 100 L or more of the liquid to be treated was defoamed under 24-hour contact conditions, including system start-stops. This is presumably due to a decrease in the effective membrane area for bubble removal caused by clogging with organic matter during the defoaming process. Comparative Example 1 demonstrates that hollow fiber membranes with nano-sized pores have a short lifespan when treating water containing organic matter. [Explanation of symbols]

[0047] 1. Treated water collection section 2 Raw water inlet pipe 3. Defoaming equipment for organic-containing water 4 membrane 5 Liquid phase chamber 6. Gas Phase Chamber

Claims

1. A defoaming treatment apparatus for organic-containing water having a membrane for removing bubbles from organic-containing water, and a liquid phase chamber and a gas phase chamber separated by the membrane, The defoaming treatment device for organic matter-containing water is characterized in that the membrane is a hydrophobic porous membrane having pores of 0.1 to 2 μm.

2. A defoaming treatment apparatus for organic-containing water having a membrane for removing bubbles from organic-containing water, and a liquid phase chamber and a gas phase chamber separated by the membrane, The defoaming treatment device for organic matter-containing water is characterized in that the membrane is a hydrophobic membrane having a skin layer.

3. 3. A defoaming treatment device for organic matter-containing water according to claim 2, wherein said hydrophobic membrane having a skin layer is a hollow fiber membrane.

4. The hollow fiber membrane is disposed in a hollow fiber membrane arrangement chamber of a vessel, and a water collection pipe is installed in the vessel; 4. The defoaming treatment apparatus for organic matter-containing water according to claim 3, wherein said water collection pipe is provided with a slit.

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