Defoaming treatment device for water containing organic matter

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

[0006] , ,

[0001] The present invention relates to a defoaming treatment apparatus for water containing organic substances, and particularly to a defoaming treatment apparatus for water containing organic substances suitable for use in a water regeneration apparatus in a microgravity space.

Background Art

[0002] In a closed space in a microgravity environment such as a space station, the regeneration of recovered water is important. However, in a microgravity environment, buoyancy does not act, so a large amount of bubbles are mixed in the recovered water. When using a centrifuge, about 90% of the bubbles can be removed. However, in the case of a water regeneration apparatus that requires regeneration into drinking water with a high recovery rate, it is necessary to use organic substance-containing drainage without bubbles as raw water.

[0003] Patent Document 1 describes a bubble separation apparatus using a degassing membrane as a defoaming treatment apparatus for water containing organic substances. In Patent Document 1, a porous membrane made of a fluororesin or polypropylene is preferably used as the degassing membrane. Generally, the pore diameter of a porous membrane made of a fluororesin or polypropylene is about 10 to 50 nm. [[ID=]18]

[0004] Patent Document 2 describes degassing of boiler water using a degassing membrane module provided with a hollow fiber membrane having a skin layer. The skin layer is a dense layer that does not have pores of a size that can be confirmed by a scanning electron microscope (Patent Document 2, paragraphs 0034 to 00035).

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0006] When organic matter-containing water is degassed using a degassing membrane, the pores (approximately 30 nm in diameter) become clogged in a short period, reducing the bubble removal rate. Even if the clogged degassing membrane is cleaned using the manufacturer's recommended method (IPA + acid + alkali cleaning), its performance does not recover, and the degassing membrane needs to be replaced. While there is a method to extend the lifespan by increasing the membrane surface area, this results in a larger degassing membrane module. Furthermore, evaporation from the pores can reduce the recovery rate of treated water.

[0007] The object of this invention is to provide a defoaming apparatus for organic matter-containing water that can remove bubbles from organic matter-containing water with a high defoaming rate. [Means for solving the problem]

[0008] The gist of this invention is as follows:

[0009] [1] A defoaming apparatus for organic matter-containing water having a membrane for removing bubbles in organic matter-containing water, and a liquid phase chamber and a gas phase chamber separated by the membrane, The defoaming apparatus 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 apparatus for organic water having a membrane for removing bubbles in organic water, and a liquid phase chamber and a gas phase chamber separated by the membrane, The defoaming apparatus for organic matter-containing water is characterized in that the membrane is a hydrophobic membrane having a skin layer.

[0011] [3] The defoaming apparatus for organic matter-containing water according to [2], characterized in that the hydrophobic membrane having the skin layer is a hollow fiber membrane.

[0012] [4] The hollow fiber membrane is arranged in the hollow fiber membrane chamber of the vessel, and a water collection pipe is installed inside the vessel. A defoaming apparatus for organic matter-containing water, characterized in that a slit is provided in the water collection pipe [3]. [Effects of the Invention]

[0013] The defoaming apparatus for organic matter-containing water according to 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 apparatus for organic matter-containing water according to the second invention has a liquid phase chamber and a gas phase chamber separated by a hydrophobic membrane having a skin layer. In either of the defoaming apparatuses for organic matter-containing water, the liquid to be treated is flowed into the liquid phase chamber to remove bubbles.

[0014] The defoaming treatment device for organic matter-containing water according to the first invention can remove bubbles with a small membrane area, contributing to miniaturization. Furthermore, because the pore size of the membrane of the defoaming treatment device for organic matter-containing water according to the first invention is large, the rate of clogging by organic matter is small, resulting in a long lifespan.

[0015] The defoaming treatment device for organic matter-containing water according to the first invention requires a small pressure on the liquid phase side, enabling low-pressure operation and resulting in power savings for pumps and other equipment.

[0016] The skin layer of the membrane in the defoaming treatment device for organic matter-containing water of the second invention has a dense structure without pores, and therefore does not become clogged. Consequently, it has a remarkably long lifespan.

[0017] Generally, hydrophobic membranes with a skin layer do not have pores and therefore do not have a pore-based bubble removal function. As a result, their bubble removal performance per unit area is inferior to that of porous membranes, requiring a larger membrane area and thus resulting in a larger overall size. However, in the defoaming treatment device for organic matter-containing water of the second invention, by arranging a water collection pipe with slits, sufficient time can be ensured for bubbles in the water to be treated to come into contact with the hollow fibers, making it possible to remove bubbles sufficiently even with the same membrane area as in conventional devices.

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

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

Mode for Carrying Out the Invention

[0020] Hereinafter, embodiments of the present invention will be described in detail with reference to FIG. 1.

[0021] In FIG. 1, the water to be treated (raw water) composed of organic matter-containing water in the water to be treated collection unit 1 is supplied to the liquid phase chamber in the defoaming treatment device 3 for organic matter-containing water through the raw water inflow pipe 2. The inside of the defoaming treatment device 3 is partitioned into a liquid phase chamber 5 and a gas phase chamber 6 by a membrane 4. While the raw water flows through the liquid phase chamber 4, the bubbles in the raw water permeate through the membrane 4 and move into the gas phase chamber 6, and the bubbles in the raw water are removed. The treated water from which the bubbles have been removed is taken out through the treated water pipe 7.

[0022] In the case of the first invention, a porous membrane with a pore diameter of 0.1 to ²μm, preferably 0.5 to 1.5μm is used as the membrane 4. In the first invention, since the pore diameter of the membrane is large, the clogging rate by organic matter is small and it has a long life. However, if the pore diameter is too large, the amount of water permeating through the membrane increases along with defoaming, which is not preferable. In the case of the first invention, the differential pressure between the gas phase chamber 6 and the liquid phase chamber 5 of the degassing membrane may be small, the pressure in the liquid phase chamber 4 may be 2MPa or less, particularly about 0 to 20kPa, and the gas phase chamber 6 may be depressurized to a negative pressure or may be at normal pressure.

[0023] It is preferable to set the gas permeation flux per unit area to 0.1 to 200m / min, particularly 1 to 100m / min. Here, the membrane area is the area on the raw water supply side when the membrane is regarded as a plane without considering the pore diameter of the membrane.

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

[0025] As the housing for the defoaming treatment device for organic matter-containing water according to the first invention, a gas-liquid separation separator SEP-200 (manufactured by Zaiput Flow Technologies, Inc.) can be used. By loading a hydrophobic membrane with pores of 1 μm or less into the SEP-200, a long-life defoaming treatment can be achieved.

[0026] In the case of 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 of either an internal pressure type or an external pressure type, as long as the skin layer is in contact with the liquid in the liquid phase chamber.

[0027] It is preferable to set the membrane area such that the gas permeation flux per unit membrane area is 0.01 to 2 m / min, and particularly 0.1 to 1 m / min. Here, membrane area refers to the area of ​​the membrane on the raw water supply side, assuming the membrane is a plane and not considering the pores of the membrane.

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

[0029] The G923 degassing membrane module consists of hollow fiber membranes arranged longitudinally within a pressure-resistant vessel. The vessel is divided into a hollow fiber membrane chamber and a gas outlet chamber by a partition wall made of potting material located at one end of the vessel's longitudinal direction. A raw water inlet is provided on the side of the vessel. Raw water is introduced into the hollow fiber membrane chamber from this inlet.

[0030] Numerous hollow fibers are arranged longitudinally within a hollow fiber membrane chamber. One end of the hollow fiber membrane is sealed, and the other end is held in place by a partition made of potting material. The inside of the hollow fiber membrane is in communication with the gas outlet chamber.

[0031] A water collection pipe is positioned 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 extends outside the vessel, penetrating a bulkhead made of potting material and the vessel end plate.

[0032] Numerous slits are provided on the outer surface of the portion of the water collection pipe that is located within 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 spaced evenly apart. The opening ratio of the water collection pipe (total opening area of ​​slits / area of ​​the outer surface of the water collection pipe) is preferably about 20 to 50%.

[0033] Raw water supplied to the hollow fiber membrane chamber is degassed upon contact with the hollow fiber membrane and then flows into the water collection pipe through the slits. The bubbles permeate the hollow fiber membrane and then flow out into the gas outlet chamber.

[0034] With this G923 degassing membrane module, sufficient contact time is ensured between the air bubbles and the hollow fiber membrane (which has a skin layer), enabling degassing treatment, and sufficient air bubble removal is possible even with a small module (e.g., φ60mm × L140mm).

[0035] In the defoaming treatment device for organic matter-containing water of the second invention, which uses a hollow fiber membrane having a skin layer, it is preferable to set the pressure on the liquid phase side to 130 kPa or more, and particularly to 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 needs to be in contact with the liquid phase. If the skin layer is on the outside of the hollow fiber, the liquid phase should be on the outside of the hollow fiber; if the skin layer is on the inside of the hollow fiber, the liquid phase should be on the inside of the hollow fiber.

[0037] In the present invention, examples of organic matter-containing water include water containing ethanol, acetic acid, and silane-based organic substances with a TOC of 0.5 to 1000 mg / L. A TOC of approximately 100 to 200 mg / L is particularly preferred. Specifically, examples include condensed water from temperature and humidity control devices. The bubble content in this organic matter-containing water is typically around 10 to 20 vol%. [Examples]

[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 ethanol, 20 mg / L acetic acid, and 20 mg / L-Si silane-based organic matter, with a TOC of 180 mg / L and a bubble content of 10 vol%, was subjected to defoaming treatment (a test solution simulating condensate generated on the International Space Station).

[0040] [Example 1] A hydrophobic porous membrane having pores with a diameter of 1.0 μm (manufactured by ZaiputFlow technologies) was attached to a gas-liquid separation separator SEP-200 (manufactured by ZaiputFlow technologies) to constitute the defoaming treatment device for organic matter-containing water according to the first invention.

[0041] <Experiment and Results> The 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 kept at atmospheric pressure. As shown in Figure 2, a total of 4800 L of liquid could be defoamed under 600 hours of contact conditions with the treated liquid, including system start and stop cycles. It should be noted that the defoaming rate began to decrease when processing more than 4800 L, suggesting that membrane clogging progressed in volumes above this level.

[0042] [Example 2] The second invention's degassing treatment device for organic matter-containing water was constructed by mounting 2000 hydrophobic porous membranes (manufactured by 3M) with a skin layer as hollow fibers onto 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 (total slit opening area / area of ​​the outer surface of the water collection pipe) was 50%.

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

[0044] As a result, as shown in Figure 3, a total of over 18,000 L of defoaming treatment was possible under 2,400 hours of contact conditions with the treated liquid, including system startup and shutdown. During this time, a defoaming rate of 100% was maintained, and no membrane clogging occurred.

[0045] [Comparative Example 1] In Example 2, the degassing treatment was performed 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 water was defoamed under 24-hour contact conditions for the treated liquid, including system startup and shutdown. It is presumed that this was due to a decrease in the effective membrane area for bubble removal caused by clogging of organic matter during the defoaming process. From this Comparative Example 1, it was found that hollow fiber membranes with nano-sized micropores have a short lifespan when treating water containing organic matter. [Explanation of symbols]

[0047] 1. Water to be treated collection section 2 Raw water inlet pipe 3. Defoaming treatment device for water containing organic matter 4 membrane 5 Liquid phase chamber 6. Gas-phase chamber

Claims

1. In a defoaming apparatus for organic matter-containing water having a membrane for removing bubbles in organic matter-containing water, and a liquid phase chamber and a gas phase chamber separated by the membrane, The film is a hydrophobic film having a skin layer, The hydrophobic membrane having the skin layer is a hollow fiber membrane. The hollow fiber membrane is installed in the hollow fiber membrane deployment chamber of the vessel, and a water collection pipe is installed inside the vessel. The water collection pipe is provided with slits, The defoaming apparatus for organic matter-containing water is characterized in that the organic matter-containing water is condensed water from a temperature and humidity control device, containing ethanol, acetic acid, and silane-based organic substances, with a TOC of 0.5 to 1000 mg / L and a bubble content of 10 to 20 vol%.

2. The skin layer of the hollow fiber membrane is in contact with the liquid phase of the liquid phase chamber, The defoaming apparatus for organic matter-containing water according to claim 1, wherein the pressure of the liquid phase is 130 to 200 kPa.

3. The defoaming apparatus for organic matter-containing water according to claim 1 or 2, wherein the temperature and humidity control device is a temperature and humidity control device for a space station.

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