JPH0330889A - Water purifier and water purifying method - Google Patents

Abstract

PURPOSE:To obtain high deodorizing effect and high harmful matter removing effect by allowing water to be treated to branch from a raw water flow passage to supply the same to one surface of the diaphragm in a hollow fiber-like diaphragm type gas- liquid contact module which is hydrophobic and has au oxygen transmission rate of a specific value or more and removing harmful matter out of the system along with the water supplied to a water flow aspirator. CONSTITUTION:In a bellow fiber-like diaphragm type gas-liquid contact module 1 wherein a diaphragm is hydrophobic and an oxygen transmission rate is 1X10<-5>[cm<3>/cm<2>, sec, cmHg] or more, water to be treated is allowed to branch from a raw water flow passage to be supplied to one surface of the diaphragm and a part of the water to be treated is allowed to branch from the raw water flow passage to be supplied to the water flow aspirator 2 connected to the module 1 in order to reduce pressure on the other side of the diaphragm and the malodorous matter or harmful matter in the water to be treated is removed out of the water purifier system through the diaphragm along with the water supplied to the water flow aspirator 2. Therefore, excellent deodorizing capacity of water is developed and high removing capacity to the malodorous substance or volatile harmful matter apt to be mixed with tap water or ground water is provided. Maintenance cost is reduced as compared with an adsorbing type water purifier.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method and apparatus for deodorizing drinking water, and also relates to a method and apparatus for removing volatile harmful substances contained in water, and also relates to a method and apparatus for deodorizing drinking water. This invention relates to a diaphragm gas-liquid contact type water purifier that does not require extensive replacement or maintenance and is easy to handle. It is particularly suitable as a water purifier for household use, the restaurant industry, the food manufacturing industry, and the like.

[Conventional technology]

In recent years, the quality of tap water has deteriorated due to population concentration in cities and eutrophication of wastewater, resulting in a significant increase in foul odors from equipment and chlorine smells. People's lives are becoming richer, and there is a growing demand for so-called "tasty water" when it comes to drinking water. Furthermore, with the increase in the amount of chlorine added to tap water, trihalomethanes, which are said to be carcinogenic, are increasing, and trichlorethylene contamination of underground water has become a problem, and there is a strong demand for ``water that is safe to drink.''

Against this background, the popularity of household water purifiers has been remarkable, but all household water purifiers currently on the market are either adsorption types using activated carbon or the like, or types that combine adsorption and filtration. However, these types have a short adsorbent life and lose their deodorizing effect after about a month.
This method requires frequent replacement of the adsorbent, is time-consuming to maintain, and has the drawbacks of high maintenance costs.

In addition, there was a risk that the ability to remove tasteless and odorless harmful substances would decrease without people noticing, and they would continue to ingest them without realizing it.

[Problem to be solved by the invention]

An object of the present invention is to provide a water purifier that has high deodorizing effects and harmful substance removal effects, requires no maintenance and management costs, is inexpensive, and is capable of deodorizing using a diaphragm gas-liquid contact method. It is in.

[Means to solve the problem]

That is, the present invention includes a hollow fiber-like diaphragm, through which water to be treated flows inside or outside, and the diaphragm is hydrophobic and has an oxygen permeation rate of I x 10-5 [National 3/32. Clal Hatake
A hollow fiber diaphragm type gas-liquid contact module having a pressure of IHg or higher, a water flow aspirator connected to the module so as to reduce the pressure on the opposite side of the water to be treated separated by the hollow fiber diaphragm, and a water flow aspirator connecting the water to be treated to the raw water flow. A diaphragm gas-liquid contact type water purifier is constructed of a diaphragm gas-liquid contact type water purifier, which is configured with pipes connected to the module tube and the seven subilators, each branched from the pipe separately, and in particular, the module is a hollow fiber-shaped water purifier. In the above-mentioned water purifier in which a diaphragm is incorporated in a characteristic structure, the water to be treated is supplied to one side of the diaphragm in a hollow fiber diaphragm type gas-liquid contact module by dividing it from the raw water flow path. , a part of the water to be treated is divided and supplied from one raw water flow path to a water aspirator connected to the module so as to reduce the pressure on the other side of the diaphragm, and odor substances and harmful substances in the water to be treated are removed through the diaphragm. A water purification method characterized in that substances are removed from the water purifier system together with water supplied by a water aspirator.

Discussing the main parts of the present invention in more detail, the F! The hollow fiber diaphragm used in AK has an oxygen permeation rate, which is a representative value of gas permeation rate, at 25°C.
16=, 5 [3(8TP)/am”, m*e, a
*Hg] or more. When the object to be removed from water is a gas such as oxygen or carbon dioxide, the oxygen permeation rate of the membrane is I
/J#l@e, cynHgAlthough it is possible to remove at a practical level, it is insufficient for the purpose of the present inventionjl), lXl0''-5[m3(8TP)/
J, 1 ull, mHg], the removal rate of volatile substances becomes impractically slow.

Furthermore, the membrane of the present invention needs to be hydrophobic. If the membrane is hydrophilic, water will enter the inside of the membrane, drastically reducing the rate of removal of malodorous substances, etc., and water will also permeate through the membrane, rendering the diaphragm useless.

That is, although the membrane used in the present invention may partially contain a hydrophilic portion, it is a membrane through which only volatile substances can pass through without allowing water to pass therethrough in the form of a liquid. This unique material is
For example, poly4-methylpentene-1, polypropylene,
Polyolefins such as polyethylene, fluorine-based polymers such as polyvinylidene fluoride, polytetra-70-roethylene, fluorinated ethylene-no-70-roalkylpierrether copolymer, polyethers such as I-lyacetal, ppo%PPs, ilithioether, polyester, etc. Examples include chlorine-containing polymers such as vinyl chloride and polyvinylidene chloride, as well as polyetherketone, polysulfone, and polyethersulfone.

Preferred membrane types for the present invention are firstly heterogeneous membranes or composite membranes having an oxygen/nitrogen separation coefficient of 1.0 or more. The oxygen/nitrogen separation factor is the oxygen permeation rate divided by the nitrogen permeation rate. If the diaphragm is a porous membrane of continuous pore type, the value of the oxygen/nitrogen separation coefficient will be 0.935. An oxygen/nitrogen separation coefficient of 1.0 or more means that a non-porous layer is present in the membrane. Homogeneous membranes or composite membranes are superior to porous membranes in that water does not leak even after long-term use of the diaphragm. Such films are disclosed in, for example, Japanese Patent Application Laid-open No. 59-196706 and Japanese Patent Laid-open No. 59-59209.
, JP-A-57-122906, JP-A-63-27443
It can be manufactured by the method described in 3.

Another preferred membrane type for the present invention is a continuous pore type porous membrane, with a bubble point of 1.0 [kli'/
m2G ] or more. The bubble point referred to here is a value measured according to ASTM F-316 using a low viscosity silicone oil having a surface tension of 17 to 19 dyn/ct11 as a wetting liquid. If the bubble point is less than 1.0 kg/cfR2G, water will easily enter the pores even if the membrane material is hydrophobic. When the membrane is a porous membrane with open pores, the gas permeation rate of the membrane needs to be higher than that of a heterogeneous membrane or a composite membrane, and I x 10-'[m' (STP)7 'm'',
asc.

It is preferable that it is more than mHg. Such a membrane is
For example, Special Publication No. 56-52123, Special Publication No. 60-1484
4. It can be manufactured by the method described in JP-A-56-56202 and the like.

The membrane of the present invention has a hollow fiber shape. Compared to film-like membranes, hollow fiber membranes have the advantage of allowing a larger membrane area per device volume, allowing the device to have smaller wrinkles. The dimensions of the hollow fiber are as follows: When water is allowed to flow inside (internal perfusion type), the inner diameter is 3.
The thickness is preferably 0 to 300 μm, particularly preferably 80 to 200 μm. If it is less than 30 μm, it will be difficult to manufacture;
When it exceeds 0 μm, the removal efficiency per membrane area deteriorates. When water is allowed to flow outside the hollow fiber (external perfusion), the outer diameter of the hollow fiber is preferably 50 to 1000 μm. If it is less than 50 μm, it will be difficult to manufacture, and if it exceeds 1000 μm, the volumetric efficiency will deteriorate.

The hollow fiber membrane is used in the form of a housing (referred to as a module). In the case of a usage method in which water is allowed to flow inside the hollow fiber (internal perfusion), the shape of the module is not particularly limited, and for example, a shape commonly used for artificial kidneys as shown in FIG. 2 can be used. That is, raw water is introduced into the module from the water supply port (8), flows from the end face of the hollow fiber membrane sealed with resin (6) to the inside of the hollow fiber membranes (5) loaded in a bundle, and is discharged. The treated water is discharged from the outlet (9). On the other hand, the space between the outside of the hollow fiber membrane and the housing (7) is depressurized by an aspirator through the suction port (10).

In the case of usage in which water flows outside the hollow fiber (external perfusion),
In order to prevent the removal efficiency from decreasing due to uneven water flow (channeling) caused by uneven filling of hollow fibers, etc.
Hollow fibers are in the state of a stack or convergence of sheet-like objects organized by hollow fibers or with other threads, or in the state of a three-dimensional braided body organized by hollow fibers or with other threads. It is preferable that the housing be incorporated into the housing.

A specific example of this is, for example, Japanese Patent Application No. 63-255938, *m
Showa 63-257364. It is described in Japanese Patent Application Laid-Open No. 52-143974. - Example t - Shown in FIG. Water supply port (8
) The raw water introduced into the module flows through the outer surface of the hollow fiber membrane (5), which is braided in a blind shape and packed in layers as shown in Fig. 4, and flows through the outlet (9). It is then discharged as treated water. On the other hand, connect the inside of the hollow fiber membrane to the suction port (10).
Reduce the pressure further using an aspirator.

The principle of the water purifier of the present invention is to remove volatile malodorous substances and harmful substances contained in high-concentration water to the gas phase by bringing the water phase into contact with the reduced pressure gas phase through a membrane. It is.

In the present invention, a water aspirator is used as the pressure reducing means. In general, oil rotary vacuum bonders, piston type vacuum bonders, water ring vacuum bonders, steam ejectors, etc. are known as pressure reduction means, but these are expensive and require maintenance such as oil changes and lubrication. It is not suitable for general households or small restaurants where many reeds and water purifiers are installed.

Water aspirators have drawbacks such as a small displacement, limited depressurization, and the need for a large amount of water flow, so they are not suitable for large-scale applications, but as household equipment they are small and The advantages of being lightweight, inexpensive, vibration-free, power-free, and maintenance-free are maximized. If the spacing of the present invention is used, sufficient deodorizing effects can be achieved regardless of the displacement amount of the aspirator or the degree of pressure reduction.

In addition, malodorous and harmful substances removed from the water are discharged together with the aspirator drainage, so they are not dispersed into the air and cannot be washed, trapped, or There is no need for suction operations. Thus, a small water purifier (aspirator) is a particularly suitable pressure reducing means.

One feature of the present invention is that untreated feed water is divided and used as pressurized water for driving the aspirator. That is, when purifying tap water in a general household, the same tap water is used as a drive source for an aspirator without providing any special pressurizing means. The discharged water will not be recycled, but will be disposed of as is. This method of using an aspirator is inefficient, so it is not usually used industrially, but for small-scale water purifiers such as those for home use, it is easier to handle, maintenance-free, and equipment cost is better than water loss. The benefits, such as the reduction in From this point of view, the water purifier of the present invention is particularly advantageous in the case of a small water purifier with a processing speed of 10 liters per minute or less.

According to theoretical considerations, when the feed water to be treated is used as the driving source for the 7 aspirators as in the present invention, the volatile substances to be removed in the aspirator part also transfer from water to the gas phase, so the membrane It is presumed that there is no difference in partial pressure between the front and back sides of the membrane, so that it is not removed through the membrane. However, it is unexpected and surprising that it is actually effectively removed.

The configuration of this water purifier branches raw water, one of which is guided to a membrane module (1), and the other of which is supplied to an aspirator (2).

A shut pulp (3) and/or a flow rate regulating valve (4) can be provided as necessary. The purified water outlet from the water purifier can be in the form of a faucet, hose, or other suitable form for use.

The water supplied by the water purification method of the present invention is suitably water that is suitable for drinking. However, this is not the case when water treated by the method of the present invention is sterilized by boiling or the like.

The target substances removed from water in the present invention are volatile substances. For example, malodorous substances include chlorine, ozone, 2-methylisogelneol, diosmin, amines, ammonia, and the like. Among these, the feature of the present invention is that it can effectively remove chlorine odor, which is the main cause of bad odor in tap water. Examples of harmful substances include trihalomethane represented by chloroform, trichloroethylene, tetrachloroethylene, 1.1.1-)lichloroethane, carbon tetrachloride, and chloropicrin. Although adsorption-type water purifiers have poor removal efficiency for these substances, the present invention can also effectively remove these substances. The objects to be removed are not limited to these known substances.
It also includes volatile substances whose names have not been identified. It is surprising that the substances that can be removed, including those with boiling points higher than water, are effectively removed by the apparatus of the present invention.

At first glance, it seems easy to infer that volatile substances such as those mentioned above can be removed (from water) by means of a diaphragm-type gas-liquid contacting device. However, in order to remove malodorous substances to below the detection limit, in many cases the residual concentration is on the order of ppm or less, and depending on the substance, the residual concentration is on the order of ppm (10 ppm).
) must be removed to the order of magnitude. In the diaphragm type gas-liquid contact device known so far, volatile dissolved substances in the liquid, especially substances that are liquid at room temperature, t ppm
[It is a difficult technique to remove the residual amount to an extremely low level of less than an order of magnitude], and it was not known that it could be used for such purposes. The present invention has found that depending on the configuration of the diaphragm, the device, and other conditions, it is possible to remove low vapor pressure substances that are liquid at room temperature from a relatively high viscosity liquid such as water to a ppm order or less. , has been completed.

〔Example〕

EXAMPLES The present invention will be explained in more detail with reference to Examples below, but the present invention is not limited to these Examples.

Example 1 Poly4-methylinthene-1 with melt index 26
Melt spinning was performed using a spinning temperature of 290°C and a draft of 200, and the obtained hollow fiber intermediate was heated at 200°C with a fixed length
Heat treatment for 60 seconds, cold stretching at 25 °C, draw ratio (DR) 1.2, hot stretching at 150 °C, DR = 1.5, and 180 °C
By performing heat fixation at ℃ and D R = 0.9, a hollow fiber membrane having an outer diameter of 252 μm and an inner diameter of 200 μm was obtained. When this membrane was observed under a scanning electron microscope, many pores with a diameter of 0.1 μm were observed on both the inner and outer surfaces of the hollow fiber membrane.

The average pore diameter measured by a mercury porosimeter is O,OS
It was μm. When 70% ethanol (aqueous solution) is introduced into the inside of this membrane at a pressure of f 0.5 kg/cts2G, ethanol has a pressure of 200 cP! 1/m, mi
It penetrated at a rate of n. This shows that this membrane has pores that connect the inner and outer surfaces. Silicone oil/l/ as a wetting liquid (PITRACHSYSTK
Manufactured by MS, Plil-036, surface tension 18 dyn
The bubble point (ASTM, F-316K!) measured using a viscosity of 1.5eSt) is 10
kg7am2G (measurement limit) or more.

Also, the gas permeation rate of this membrane in the gas-gas system (A8TM
, F-316, by Dry method) has an oxygen permeation rate (QO2) of 3.20 x 10-3 [m3 (STP)
7cm", see, zHg, 'Iil elementary permeability overrate 2) 3.42 X 10-s [same unit], oxygen/
The nitrogen separation coefficient was 0.936.

This membrane was assembled into a module having an inner surface area of 3.2 m2 as shown in FIG. 2 to construct the water purifier shown in FIG.

As an aspirator, MA-2m manufactured by Nishidewara Melatory was used. This water purifier was connected to a 9/m" GO water supply with a water pressure of 3.5, and the amount of treated water was adjusted to 0.5 liters per minute using Pulp 4.The chlorine odor felt in the raw water was According to the DPD colorimetric analysis method, the chlorine concentration in the raw water was reduced from 0.7 ppm to about 0.2 ppm.

Example 2 Using the same water purifier as that used in Example 1, distilled water to which 20 ppt of 2-methylisogelneol was added was pressurized to 5 kg/a112G with a pump and used as raw water. The results of a sensory test on water treated at 0.51 J/min showed that the equipment used for raw water was halved for treated water.

Example 3 As a hollow fiber membrane, a polypropylene porous membrane (1e Riderastics Co., Ltd., X-10, pore size 0.2 to 0.3 x 0.4
The same test as in Example 1 was conducted except that µm) was used. The actual measured value of this membrane is 268 μm in outer diameter.

Inner diameter 2074m, bubble point 3.5 kg/1ys
2G, gas permeation characteristics are QO2 = 5.77 x 10
-'[cm'(STP)/! 112. See.

mHg], and the oxygen/nitrogen separation coefficient was 0.933.

The chlorine odor that was felt in the raw water was hardly felt in the treated water, and the results of DPD colorimetric analysis showed that the chlorine concentration in the raw water was 0.7.
ppm had decreased to about 0.2 ppm. Further, when a test similar to that in Example 2 was conducted, the amount of equipment felt in the raw water was reduced to 1/2 in the treated water.

Example 4 Using the same water purifier as that used in Example 1, distilled water to which chloroform and trichlorotethane had been added was used as raw water after being pressurized to 5 kg/an2G using a bonder.

Raw water and 0.5 per minute! Water treated with J-Tuttle was measured using the Gas Chroma Dogs 7 method (Water Test Methods 1985 edition, edited by Keiji Iwamoto, published by Japan Water Works Association, p. 482).
For chloroform, 0.15 ppm becomes 0.03 ppm, and for trichlorethylene, 0.19 ppm becomes 0.04 ppm.
It had decreased to pm.

Example 5 Poly 4-methylpentene-1 with melt index 26
Melt spinning was carried out using T-T at a spinning temperature of 290°C and a draft of 300°C, and the obtained hollow fiber intermediate was heat-treated at 210°C, a draw ratio (DR) of 1.1, and a treatment time of 5 seconds at 25°C.
By performing cold stretching at DR = 1.2, hot stretching at 150 °C, DR = 1.4, and heat setting at 180 °C, DR = 0.9, a hollow fiber membrane with an outer diameter of 213srH1 and an inner diameter of 167 μm was obtained. I got it. When this membrane was observed under a scanning electron microscope, many pores with a diameter of 0.1 μm were observed on the inner surface of the hollow fiber membrane, but almost none were present on the outer surface.

Add 0.5% of 70% ethanol (aqueous solution) to the inside of this membrane.
kg/c! Although it was introduced at a pressure of 112G, no permeation of ethanol was observed. This shows that this membrane does not have pores connecting the inner and outer surfaces. In addition, the gas permeation rate of this membrane in a gas-gas system is oxygen permeation rate (O02) 1.5 1 X 1 0-5 [m
3(STP)//-III2. sea, mHg, nitrogen permeation rate (QN2) 3.80 x 10-' [same level], rIIX/nitrogen separation coefficient was 3.97.

Using this membrane, a water purifier of the same type as in Example 1 was constructed,
When the same test as in Example 1 was conducted, the DPD method only reduced the 0.7 ppm in the raw water to 0.5 ppm, but the chlorine odor felt in the raw water was not felt in the treated water. Furthermore, when the same test as in Example 4 was conducted using this membrane, chloroform was found to be 0.15 ppm.
is 0.03 ppm, and trichlorethylene is 0.19 ppm.
ppm had decreased to 0.05 ppm.

Example 6 The same hollow fiber membrane as that used in Example 5 was used, as shown in FIG. 4, using 30 denier polyester yarn as the warp.
Due to entwined weaving, the hollow fiber density is 25 15I, and the warp density is 1.
A screen-like sheet of book/α as shown in FIG. 4 was formed. This sheet was laminated and wound around a nozzle having many holes, loaded into a housing, and the end portions were sealed with I-urethane resin to form the module shown in FIG. 3. The effective membrane area (hollow fiber outer surface area) of the module is 4.2
It was m2. The same test as in Example 4 was conducted using this 7-dimer, except that Pulp 4 was adjusted so that the amount of water treated was 1 liter per minute. As a result, chloroform (0.15 ppm) in the raw water was found to be 0. O2ppm,
Trichlorethylene (0.19ppm) is 0.03p
removed by pmt. In addition, when the same test as in Example 1 was conducted, the chlorine concentration was 0.7 ppm to 0.5 ppm.
However, a clear reduction in chlorine odor was observed in the sensory test.

〔Effect of the invention〕

Compared to adsorption-type water purifiers, the present invention can effectively remove harmful substances such as trihalomethane, and does not cause elution of silver ions added to the adsorbent to prevent bacterial growth. . In addition, there is no danger that the removal ability of the adsorbent will decrease without you noticing and you will continue to ingest tasteless and odorless harmful substances.In this way, the present invention is safer than conventional water purifiers. It is excellent.

Therefore, the water purifier of the present invention has excellent performance in deodorizing water, and has a high ability to remove foul-smelling substances and volatile harmful substances that tend to be mixed into tap water or underground water.

The water purifier of the present invention also has the advantage that, compared to adsorption type water purifiers, there is no need to frequently replace consumable parts such as adsorbents, there is no cost for consumable parts, and there is no maintenance cost. have In addition, although it is a diaphragm gas-liquid contact water purifier, it can be used without a power source, so there are no electricity costs, no wiring, and it can be used in places without a power source.

Due to these features, the water purifier of the present invention is particularly suitable as a water purifier for home use or a water purifier for restaurants.

[Brief explanation of drawings]

Fig. 1 shows an embodiment of the present invention, and is a conceptual diagram showing the configuration of a water purifier, Fig. 2 is a partial vertical cross-sectional front view of an internal perfusion type membrane module used in the embodiment, and Fig. 3 is an implementation example. FIG. 4, a vertical cross-sectional front view of the external perfusion type membrane module used in the example, is a conceptual diagram of the shape of the hollow fiber sheet. The symbols in the figure are as follows. l... Membrane module, 2... Aspirator, 3...
. . . Lup, 4 . . Flow rate adjustment valve, 5 . . Hollow fiber membrane, 6 . . Resin sealing part, 7 . . Housing, 8 .
・Water supply port, 9... Treated water outlet, 10... Suction port,
11... Porous/Guib, 12... Net, 13... Warp

Claims (1)

[Claims] 1. A hollow fiber-like diaphragm is provided, the water to be treated is allowed to flow inside or outside the diaphragm, and the diaphragm is hydrophobic and has an oxygen permeation rate of 1×.
10^-5 [cm^3/cm^2, sec, cmHg]
The above-mentioned hollow fiber diaphragm type gas-liquid contact module; a water aspirator connected to the module so as to reduce the pressure on the opposite side of the water to be treated separated by the hollow fiber diaphragm;
A diaphragm gas-liquid contact type water purifier configured by a diaphragm gas-liquid contact type water purifier, which separates the water to be treated from a raw water flow path and includes pipes connected to the module and the aspirator. 2. Hollow fiber diaphragms are in the state of a stack or convergence of sheet-like materials organized by hollow fiber diaphragms or with other threads, or in a three-dimensional state in which hollow fiber diaphragms are organized with each other or with other threads. The water purifier according to claim 1, which is incorporated into the housing in the form of a braided body. 3. The water purifier according to claim 1, wherein the water purifier is of an internal perfusion type in which the water to be treated flows inside the hollow fiber diaphragm. 4. The water purifier according to claim 1, wherein the water purifier is of an external perfusion type in which the water to be treated flows outside the hollow fiber diaphragm. 5. Hollow fiber diaphragm has a bubble point of 1.0 [kg/cm
Claim 1, which is a continuous pore type porous membrane having a diameter of ^2G] or more.
The water purifier according to , 2, 3 or 4. 6. The water purifier according to claim 1, 2, 3 or 4, wherein the hollow fiber diaphragm is a heterogeneous membrane or a composite membrane having an oxygen/nitrogen separation coefficient of 1.0 or more. 7. In a hollow fiber diaphragm type gas-liquid contact module, the water to be treated is supplied by branching from the raw water flow path to one side of the diaphragm, and the water flow aspirator connected to the module is depressurized on the other side of the diaphragm. , water purification characterized by supplying a part of the water to be treated by dividing it from the raw water flow path, and removing malodorous substances and harmful substances in the water to be treated through a diaphragm to the outside of the water purifier system together with the water supplied to the water flow aspirator. Method.