JP2880913B2 - How to purify tap water - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates are those hydrophobic gaseous substances contained in tap water, to method of purifying tap water can be particularly removing trihalomethane.

[0002]

2. Description of the Related Art At present, water purification treatment is generally carried out by first injecting chlorine into raw tap water taken from a river or the like to sterilize and disinfect and oxidatively decompose inorganic and organic pollutants. Activating such as sterilization is prevented by leaving a predetermined concentration of chlorine in the treated water after the injection, and then a flocculant is injected to perform a flocculant precipitation treatment for removing turbid components in the raw water. The filtration by the rapid filtration method is performed.

[0003] By the way, tap water contains a substance harmful to the human body called trihalomethane (hereinafter referred to as "THM").

[0004] THM is produced by the reaction of chlorine and humin in tap water.

[0005] During the year from April 1981 to March 1982, the analysis team of the Liaison Committee on the Yodo River and Water Issues conducted an investigation on the THM content of tap water sampled at the faucet of the Yodo River water system.

[0006] As a result, it has been found that the value of THM is higher at a water sampling point downstream than in the upstream of the Yodo River.

[0007] This indicates that the THM content value is proportional to the distance from the upstream water purification plant to the water sampling point.

[0008] That is, the longer the contact time between chlorine and humin in tap water, the more THM is generated.

However, in a water purification plant, there is an obligation to add a standard amount of chlorine to tap water in order to maintain the sterilizing action as described above.

Therefore, when tap water is used at a point distant from the water treatment plant, while flowing over a long distance from the water treatment plant to the point of use, chlorine and humin react as described above to cause THM.
Is generated.

[0011] Accordingly, while continuing to drink such tap water, THM gradually accumulates in the human body, which may cause harm to the human body.

As a method for removing THM from tap water, an activated carbon treatment method is known. This removes THM by adsorbing it on activated carbon, and a high removal rate of THM can be obtained. However, to implement this activated carbon treatment method, it is necessary to install an activated carbon filter pond, etc., and it is difficult to implement it easily with existing water purification equipment that mainly uses the rapid filtration method. Although it is effective for the THM that has been made, it is of course ineffective for the THM generated between the water purification plant and the faucet.

In Japanese Patent Application Laid-Open No. 58-137409, a coagulant is also injected before chlorine injection to microfuculate the humic substance which is a precursor of the THM, and contact with chlorine injected later is performed. By inhibiting, THM
Although a method of suppressing generation is described, this method can reduce only about 40% of THM.

JP-A-58-174207 discloses TH
Note that the amount of M production increases at high pH values (eg, about pH 7.5 to 8.0 or higher).
A method for reducing the production of THM by controlling the pH to a slightly acidic side (for example, about pH 6.0 to 6.5) is described. In this method, it is considered that the reaction of generating THM is delayed due to the reaction equilibrium, and it is considered that a large amount of THM is generated if the contact time between chlorine and humic substances is sufficiently long.

[0015] Therefore, it is difficult to always set the THM contained in tap water to a certain reference value or less in the above-mentioned prior art.

[0016] Therefore in view of the above circumstances, the present invention removes the most of the T HM you contained in tap water, it is an object always is to provide a method of purifying tap water supply safe tap water.

[0017]

The above objects can be achieved by the present invention described below.

[0018] Namely, the present invention is hydrophobic gaseous including trihalomethanes or this hollow fiber tube <br/> tap water is gaseous material permeable nonporous polymeric membrane via the primary side of hollow fiber a method of purifying tap water which passes through removing material, wherein
Substantially uniform silicone rubber resin as polymer film
Essentially non-porous material consisting of various layers and having no pores on the inner and outer surfaces
Using the polymer membrane, trihalo hollow fiber extravascular a secondary side
The present invention relates to a method for purifying tap water, which comprises setting a negative pressure sufficient to remove methane . Hereinafter, “water” indicates “tap water”.

The shape of the polymer film is a hollow fiber .
In, suitable for mass treatment. Material of the membrane, since the silicone rubber-based resin, is excellent in terms of gas permeability and durability
You .

The above-described method of the present invention is particularly suitable for removing THM among hydrophobic gaseous substances. Further, it is preferable to remove THM by the above-described method after removing residual chlorine in water, since the removal rate of THM increases.

If a water circulation means is provided to circulate the water so that the water is repeatedly purified, clean and safe water with a high degree of purification can be supplied.

[0022]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The purification method of the present invention
(Tap water purified at a water treatment plant).

[0023] In the present invention the hollow fiber moth <br/> scan matter permeable polymeric substance specified in the present invention film (non-porous polymeric membrane)
Through water the hollow fiber tube, on the side which is filled with water can be added to the pressure, preferably, it has not met in the water
A vacuum is applied to the side (outside the hollow fiber tube) , and a pressure difference is provided on both sides of the membrane to separate trihalomethane or a hydrophobic gaseous substance containing the same from water.

In the method of the present invention, a negative pressure (including vacuum ) is applied to the side of the polymer membrane not filled with water (outside the hollow fiber tube ).
You to. This is because the pressurizing means such as a pump may generate a pressure greater than the set pressure instantaneously when the switch is turned on.
This is because the vacuum pump gradually becomes negative pressure when the switch is turned on, so that the load on the membrane can be reduced.

The gaseous substance-permeable polymer material membrane used in the present invention is in the form of a hollow fiber and silicone.
It is essentially non-porous, consisting of a substantially uniform layer of a rubber-based resin and having no pores on its inner and outer surfaces. The gas removal according to the present invention is selectively permeated only depending on the gas permeability, which is a characteristic of the polymer membrane.

[0026] In the film of a high molecular material, a silicone rubber resin, polyolefin resin, ethylene tetrafluoride resins, polyvinyl alcohol resins, polyacrylonitrile resins, polyimide resins, polysulfone resins, etc.
There are, gas permeability, in particular considering the permselectivity and durability against THM, containing the polymer membrane used in the present invention
A silicone rubber-based resin is selected as the material .

The hollow fiber membrane (nonporous polymer film) of polymeric material in the present invention are noted even after the film of a high molecular substance which was formed recently hollow fiber points of handling I am. As an apparatus using such a hollow fiber membrane,
As an example, a hydrophobic gaseous substance removing device as shown in FIG. 1 in which water flows from one end of the hollow fiber membrane to the other end can be considered.

The hydrophobic gaseous substance removing apparatus 1, which is one example of an embodiment for achieving the tap water purification method of the present invention, is formed of the above-mentioned polymer material film (non-porous polymer film) . Capillary tube (hollow fiber membrane) composed of aggregate of capillaries
A group of thin tubes 9 composed of, for example, 100 to 200 tubes is housed in a tank 10, and one end of the thin tube group 9 is connected to an inflow pipe 11 of water, and the other end is connected to an outflow pipe 12. They are communicating.

An intake pipe 13 is connected to the tank 10, and a free end of the intake pipe 13 is connected to a vacuum pump 14.

The hydrophobic gaseous substances in the water can be removed by the above method. Hydrophobic gaseous substances include oxygen and THM, and the removal of oxygen can prevent the generation of red water in water.
Safe water can be secured by removing THM, which is a carcinogen.

[0031] In this case, since the water to be treated is tap water, T
If the residual chlorine in the water is removed prior to the HM removal, T
The effect of reducing HM is enhanced. As a method for removing chlorine, a known method can be applied, and examples thereof include a method of adsorbing with activated carbon and a method of decomposing by irradiating ultraviolet rays.

The present invention maximizes its effect by incorporating a circulating means for repeatedly sending water purified by the above-mentioned hydrophobic gaseous substance removing apparatus to the hydrophobic gaseous substance removing apparatus. Thus, the amount of hydrophobic gaseous substances contained in water can be minimized.

Therefore, if the water is circulated for a certain period of time (for example, one hour) or more, water of almost stable quality can be supplied at any time. Especially for THM, a reference value of 30 ppb or less set by the World Health Organization (WHO) is provided. Water can be supplied stably.

[0034] For example, as an example of the actual embodiments with you purify <br/> tap water by the method of the present invention include a method of using the cleaning apparatus of the tap water as shown in FIG.

The tap water sent from the water purification plant 6 is collected in a water receiving tank 7 installed underground in a building or the like, and is supplied to a high water tank 8 installed on the roof of the building by a water pump (not shown). Pumped.

The high water tank 8 and the hydrophobic gaseous substance removing device 1 are connected by a water pipe 2, and a water pump 15 and a foreign matter filter 3 are mounted on the way. At this time, the amount of water supplied by the water introduction pump 15 is 0.5 to
It is good to be about 1000 t / h, preferably 1 to 300 t / h.

Then, the free end of the water pipe 2 is connected to the inflow pipe 11 of the hydrophobic gaseous substance removing device 1.

Next, one end of the circulation pipe 4 is connected to the outflow pipe 12 of the hydrophobic gaseous substance removing device 1, and the other end is connected to the elevated water tank 8.
Connect with

The free end of the water supply pipe 5 is connected to a faucet 16 of each household.

Therefore, when the faucet 16 is closed,
The tap water circulates in the circulation pipe 4 and the water guide pipe 2. When the faucet 16 is opened, the circulated tap water flows out of the faucet 16 through the water supply pipe 5.

Since the hydrophobic gaseous substance removing apparatus can be used in this manner immediately before the faucet at the end of the water supply pipe, it is possible to provide tap water in which THM is substantially removed and minimally remaining. .

The present invention relates to trihalomethane from water or
It can be applied to the removal of hydrophobic gaseous substances containing .

[0043]

The method of the present invention is characterized in that the hollow fiber-shaped
For removing trihalomethane outside the hollow fiber tube of polymer membrane
By the sufficient negative pressure, the gas permeability is a property of hydrophobic gaseous material permeable nonporous polymeric membrane, the hollow fiber trihalomethanes or from water passing through the hollow fiber tube of the polymer film of this Can be removed. In particular, THM, which is a carcinogen, can be selectively permeated and removed, and safe water (drinking water) with low THM can be provided. Further, by circulating the water repeatedly, safe water with stable water quality can be provided.

[0044]

The present invention will be described in more detail with reference to the following examples.

<Example 1> A water purification apparatus using the present invention shown in FIG. 2 was installed on the roof of a second safety car in Akasaka, Minato-ku, Tokyo. In the following examples, DO means dissolved oxygen.

The tap water currently used in the building and the treated water of the apparatus of the present invention are used as water samples. The operating conditions of the apparatus are as follows: the operating time of the deaerator is 1 hour, the flow rate is 5 t / h, and bubbles may be present.

(Sampling and transport of sample) Gently sample the sample in a 100-ml measuring cylinder with a stopper so as not to foam, add 10 drops of phosphoric acid (1 + 10) to pH 2, and further add sodium sulfite (0.5 w / v%). Was added, and the mixture was dechlorinated, filled with water, and cooled with ice.

(Quantification of THM by Solvent Extraction Method) As a water sample, 40 ml or 30 ml was placed in a 50 ml measuring cylinder with a stopper and 10 ml or 20 ml of n-hexane.
Then, the mixture was vigorously shaken and allowed to stand, and 2 μl of the n-hexane layer was measured by ECD-GC. For each sample, three samples were prepared, and two samples (one sample was spare) were measured by the same operation.

The conditions of the gas chromatogram are as follows.

Apparatus: GC-3BE (electron capture type detector) manufactured by Shimadzu Corporation Column 20% CD-550 / AW-DMCS φ3m
mx 3.0m Setting conditions: Sample inlet temperature 200 ° C Column temperature 120 ° C and 140 ° C Detector temperature 200 ° C Carrier gas Ultra-high purity nitrogen (0.8 kg / cm ² ) Under these conditions, a commercially available standard solution (Wako Pure Chemical Industries, Ltd.) Organic halide standard solution B: chloroform, bromodichloromethane, dibromochloromethane, bromoform, trichloroethylene,
Typical gas chromatograms when measuring tetrachloroethylene, 1,1,1-trichloroethane) are shown in FIGS. 3 (a) and 3 (b) and the retention time thereof is shown in Table 1.

[0051]

[Table 1]

At the same time, a calibration curve (THM (ng) / (peak area)) was prepared using a standard solution (organic halide standard solution B manufactured by Wako Pure Chemical Industries, Ltd.), and the value (an) determined from the calibration curve was obtained.
From g), the THM amount was calculated using Equation 1.

[0053]

(Equation 1)

The results are shown in Tables 2 and 3 and FIG. 4, and it can be seen that the amount of THM was reduced by using the method of the present invention. In the Safety Vehicle No. 2 Building where the experiment was conducted, bromoform was not recognized at all in THM.

[0055]

[Table 2]

[0056]

[Table 3]

(In the table,% values indicate the degree of reduction relative to raw water.)

<Embodiment 2> In the first embodiment, the operating condition of the operating device of the water purification device was not using an activated carbon filter, the operation time of the deaerator was 1 hour, the flow rate was 6 t / h, and the other operations were the same as in the first embodiment. THM was quantified.

The results are shown in Tables 4 and 5, and FIG. 5. The amount of THM was reduced by using the method of the present invention.

[0060]

[Table 4]

[0061]

[Table 5]

(In the table,% values indicate the degree of reduction relative to raw water.)

<Embodiment 3> In the first embodiment, the operating conditions of the water purification device were such that the activated carbon filter was not used, the flow rate was
THM was quantified in the same manner as in Example 1 except that water after one-pass operation and continuous operation for 2 hours was used as a water sample after setting the degree of vacuum to 720 mmHg.

The results are shown in Tables 6 and 7 and FIG. 6. The THM amount was reduced by using the method of the present invention.

[0065]

[Table 6]

[0066]

[Table 7]

(In the table, the% value indicates the reduction rate with respect to the sample water B. However, the asterisk indicates the degree of reduction with respect to the sample water D _0. )

<Example 4> The amount of residual chlorine in tap water and T
The relationship with the amount of HM was examined. The results are shown in the graph of FIG.

As can be seen from this graph, as the amount of chlorine in tap water decreases, the amount of THM decreases accordingly.
In particular, when the amount of residual chlorine in tap water decreases to 0.4 ppm or less, the amount of THM also starts to decrease significantly.

Therefore, if the residual chlorine is reduced to 0.4 ppm or less in advance before removing the THM by the method of the present invention, it is possible to not only provide delicious water free of odor but also to provide water. The effect of removing THM can be further improved.

[0071]

According to the present invention, the following effects can be expected. That is, in through the gaseous material permeable nonporous polymeric hollow fiber membrane to be specified in the present invention is a secondary side
The trihalomethane or the hydrophobic gaseous substance containing trihalomethane is permeated from the water inside the hollow fiber tube which is the primary side by a simple method of making the outside of the hollow fiber tube a negative pressure sufficient to remove trihalomethane. Can be removed. Therefore, oxygen is removed by the method of the present invention, generation of red water in water can be prevented, and THM, which is a carcinogen, can also be removed, and safe water can be secured.

[0072] The method of the present invention, because it uses a non-porous polymeric hollow fiber membrane, Ru mass treatment can der water. Further, among the materials of the non-porous polymer membrane, the silicone rubber-based resin is excellent in gas permeability, in particular, permselectivity to THM, so that water treated at low cost by the method of the present invention employing the same is used. Can be provided.

The present invention is an epoch-making method capable of selectively permeating and removing THM, which is a carcinogen, to provide safe water. That is, conventionally, when tap water is used at a point away from the water purification plant, THM is generated by the reaction of chlorine and humin before the tap water reaches the faucet, and THM is generated while drinking such tap water. In this case, trihalomethane may accumulate and cause harm to the human body.

On the other hand, the present invention can remove trihalomethane itself. Therefore, even if drinking tap water purified by the method of the present invention, there is no risk of harm to the human body such as carcinogenesis.

If chlorine is removed in advance before performing the method of the present invention, the effect of removing THM is enhanced, and safer water can be provided. Further, tasty water free of odor can be provided. . By circulating tap water and repeatedly applying the method of the present invention, trihalometa contained in water
Or the hydrophobic gaseous substances containing it are removed to a minimum.

[Brief description of the drawings]

1 is a schematic diagram of a hydrophobic gas matter removing apparatus that can be used in an embodiment of the present invention.

FIG. 2 The above hydrophobic gas that can be used in the present invention
Example 1 is a water purification device incorporating a particulate matter removal device.
It is a flowchart explanatory drawing of the water purifier used in -3.

FIG. 3 is a gas chromatogram obtained when a commercially available standard solution (organic halide standard solution B manufactured by Wako Pure Chemical Industries, Ltd.) was measured in Example 1. (A) is a chromatogram measured at a column temperature of 120 ° C, and (b) is a chromatogram measured at a column temperature of 140 ° C.

FIG. 4 shows T associated with the operation time of the water purification device in Example 1.
It is a line graph which shows HM amount.

FIG. 5 is a graph showing T associated with the operation of the water purification apparatus in the second embodiment.
It is a line graph which shows HM amount.

FIG. 6 shows T associated with the operation time of the water purification device in the third embodiment.
It is a line graph which shows HM amount.

FIG. 7 is a graph showing a relationship between residual chlorine in water and trihalomethane.

[Description of Signs] 1 ... hydrophobic gaseous substance removing device 2 ... water guide pipe 3 ... foreign matter filter (activated carbon) 4 ... circulation pipe 5 ... water supply pipe 6 ... water purification plant 7 ... water receiving tank 8 ... high water tank 9 ... narrow pipe Group 10 ... tank 11 ... inflow pipe 12 ... outflow pipe 13 ... intake pipe 14 ... vacuum pump 15 ... water guide pump 16 ... faucet

────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-63-264127 (JP, A) JP-A-6-63536 (JP, A) JP-A-6-114370 (JP, A) JP-A-2- 303587 (JP, A) JP-A-5-169051 (JP, A) JP-A-62-20693 (JP, U) JP-A-55-119102 (JP, U) JP-A-1-95943 (JP, U) Japanese Utility Model Application No. 1-124202 (JP, U) Japanese Utility Model Application No. 1-120905 (JP, U) (58) Fields investigated (Int. Cl. ⁶ , DB name) C02F 1 / 20,1 / 44 B01D 19/00 B01D 61/00-71/82

Claims (3)

(57) [Claims] 1. A hollow fiber gaseous material permeable nonporous hollow fiber tract is the primary side through the polymer membrane from the tap water tap water which passes removing trihalomethane or hydrophobic gaseous substance containing the same A purification method, wherein the polymer film is substantially made of a silicone rubber-based resin.
Consistently non-rich with uniform layer and no pores on inner and outer surfaces
Using a porous polymer membrane to remove trihalomethane outside the hollow fiber tube on the secondary side
A method for purifying tap water, characterized in that a sufficient negative pressure is provided . 2. The method according to claim 1, wherein the residual chlorine in the tap water is removed.
The removal of trihalomethane by the method described in 1.
Characteristic tap water purification method. 3. The method according to claim 1, wherein tap water is circulated.
It is characterized by repeating the above-mentioned method of purifying tap water
How to purify tap water.