KR20170084257A - Method for controlling slime on separation membrane - Google Patents

Abstract

A slime suppressing method of a separation membrane capable of reducing the content of a trihalomethane in permeated water while having a sufficient slime suppressing effect in a membrane separation apparatus using a feed or cleaning water containing a trihalomethane precursor to provide.
A bromine-based oxidizing agent, or a reaction product of a bromine compound and a chlorine-based oxidizing agent in water or washing water to a membrane separation apparatus containing a separation membrane containing a trihalomethane precursor; A bromine-based oxidizing agent, or a reaction product of a bromine compound and a chlorine-based oxidizing agent, and a sulfamic acid compound; Or a bromine-based oxidizing agent, or a reaction product of a bromine compound and a chlorine-based oxidizing agent, and a reaction product of a sulfamic acid compound are present.

Description

[0001] METHOD FOR CONTROLLING SLIME ON SEPARATION MEMBRANE [0002]

The present invention relates to a slime suppression method of a separation membrane such as a reverse osmosis membrane (RO membrane).

As a method for suppressing the slime of the separation membrane such as the reverse osmosis membrane (RO membrane), various slime inhibitors are known. Chlorine-based oxidizing agents such as hypochlorous acid are typical slime inhibitors and are usually added to the front end of the separator for slime inhibition in the system. Since the chlorine-based oxidizing agent has a high possibility of deteriorating the separation membrane, it is generally operated by reducing the chlorine-based oxidizing agent immediately before the separation membrane or intermittently introducing the chlorine-based oxidizing agent into the separation membrane (see Patent Document 1).

Patent Document 1: JP H9-057076A

It is known that a chlorine-based oxidizing agent reacts with a trihalomethane precursor such as humin in water to generate a trihalomethane such as chloroform. It has been clarified by the inventors of the present invention that the trihalomethanes produced by these chlorine-based oxidizers are difficult to be excluded by the separation membrane and are liable to leak into the permeated water of the separation membrane.

An object of the present invention is to provide a membrane separation apparatus using a water supply or cleaning water containing a trihalomethane precursor, which is capable of reducing the content of the trihalomethane in the permeated water while having a sufficient slime suppressing effect And a method for suppressing slime of the slime.

The present invention relates to a slime suppressing method of a separator in which a bromine-based oxidizing agent or a reaction product of a bromine compound and a chlorinated oxidizing agent is present in water or washing water in a membrane separation apparatus containing a separating membrane containing a trihalomethane precursor to be.

The present invention relates to a process for the production of a bromine-containing oxidizing agent or a reaction product of a bromine-based oxidizing agent and a chlorinated oxidizing agent and a sulfamic acid compound in the water or washing water in a membrane separation apparatus containing a separating membrane containing a trihalomethane precursor It is a slime suppression method of the membrane.

The present invention relates to a process for the production of a bromine-based oxidizing agent or a reaction product of a bromine compound and a chlorine-based oxidizing agent, a reaction of a sulfamic acid compound And a slime suppressing method of a separator in which a product is present.

The present invention relates to a process for the production of a reaction product of a bromine and a sulfamic acid compound or a reaction product of a bromine and a sulfamic acid compound in a water or washing water in a membrane separation apparatus containing a separating membrane containing a trihalomethane precursor A slime suppressing method of a separator.

In the slime suppressing method of the separator, a method comprising reacting bromine and a sulfamic acid compound in a mixed solution containing water, an alkali and a sulfamic acid compound by adding bromine in an inert gas atmosphere . ≪ / RTI >

In the slime suppression method of the separation membrane, it is preferable that the concentration of the trihalomethane precursor in the water supply or washing water is 0.001 mg / L or more as the trihalomethane-producing ability.

In the slime suppression method of the separation membrane, it is preferable that the separation membrane is a polyamide-based polymer membrane.

In the slime suppression method of the separation membrane, the trihalomethane precursor preferably includes humic substances.

In the slime suppression method of the separation membrane, it is preferable that the water supply or washing water further contains bromide ions.

In the slime suppression method of the separation membrane, it is preferable that the concentration of bromide ions in the water supply or washing water is 5 mg / L or more.

The slurry suppressing method of the separation membrane according to claim 1, wherein the membrane separation apparatus including the separation membrane is operated and stopped,

The bromine-based oxidizing agent, or the reaction product of the bromine compound and the chlorine-based oxidizing agent,

The bromine-based oxidizing agent, or the reaction product of the bromine compound and the chlorine-based oxidizing agent, and the sulfamic acid compound,

The bromine-based oxidizing agent, or the reaction product of the bromine compound and the chlorine-based oxidizing agent and the reaction product of the sulfamic acid compound, or

Wherein the reaction product of the bromine and the sulfamic acid compound is present.

In the slime suppression method of the separation membrane, the pH of the water present in the membrane separation apparatus is preferably at least 5.5.

In the slime suppression method of the separation membrane, it is preferable that the water present in the membrane separation apparatus is at least one of seawater and brine.

In the present invention, a bromine-based oxidizing agent, or a reaction product of a bromine compound and a chlorinated oxidizing agent, is present in water or washing water in a membrane separation apparatus containing a separating membrane containing a trihalomethane precursor; A bromine-based oxidizing agent, or a reaction product of a bromine compound and a chlorine-based oxidizing agent, and a sulfamic acid compound; By the presence of a bromine-based oxidizing agent or a reaction product of a bromine compound and a chlorine-based oxidizing agent and a sulfamic acid compound; By the presence of a mixture of bromine and sulfamic acid compounds; Or the reaction product of bromine and sulfamic acid compound is present, it is possible to reduce the content of the trihalomethane in the permeated water while having a sufficient slime suppressing effect.

1 is a schematic structural view showing an example of a membrane separation system according to an embodiment of the present invention;
2 is a graph showing the total concentration of trihalomethanes (mg / l) in treated water with respect to the concentration (mg / l) of bromide ions in the for-treatment water in Examples 4 and 5 and Comparative Example 2;

Embodiments of the present invention will be described below. The present embodiment is an example of carrying out the present invention, and the present invention is not limited to this embodiment.

≪ Method of inhibiting slime of separator &

A slime suppressing method of a separation membrane according to an embodiment of the present invention is characterized in that a "bromine-based oxidizer" is present as a slime inhibitor in water or washing water to a membrane separation apparatus containing a separation membrane containing a trihalomethane precursor Or a reaction product of a bromine compound and a chlorine-based oxidizing agent such as hypobromic acid.

A slime suppressing method of a separation membrane according to an embodiment of the present invention is a method of suppressing a slime of a separation membrane in a water separating apparatus containing a separating membrane containing a trihalomethane precursor, Sulfamic acid compound " or " a reaction product of a bromine compound and a chlorine-based oxidizing agent " and a " sulfamic acid compound " This suggests that a hypobromous acid stabilizing composition is produced in the feed water or the washing water.

The method for inhibiting the slime of the separation membrane according to the embodiment of the present invention is a method for suppressing slime of a separation membrane in which a slurry containing a bromine-based oxidizing agent and a slurry as a slime inhibitor is added to water or washing water in a membrane separation apparatus containing a separation membrane containing a trihalomethane precursor Reaction product of a sulfamic acid compound ", or a method in which a " reaction product of a bromine compound and a chlorine-based oxidizing agent and a reaction product of a sulfamic acid compound "

Specifically, the slime suppression method of a separation membrane according to the embodiment of the present invention is a method for suppressing slime of a separation membrane in a membrane separator including a separation membrane containing a trihalomethane precursor, for example, Quot ;, " bromine chloride ", " hypobromic acid ", or " a reaction product of sodium bromide and hypochlorous acid "

A slime suppressing method of a separation membrane according to an embodiment of the present invention is a method of suppressing slime of a separation membrane in a membrane separator including a separation membrane containing a trihalomethane precursor, Chloramine bromide ", " hypobromic acid " or " a reaction product of sodium bromide and hypochlorous acid "

Further, a slime suppression method of a separation membrane according to an embodiment of the present invention is a method for suppressing slime of a separation membrane in which water is supplied to a membrane separation apparatus containing a separation membrane containing a trihalomethane precursor, for example, A reaction product of a sulfamic acid compound, a reaction product of a sulfamic acid compound, a reaction product of a bromine chloride and a sulfamic acid compound, or a reaction product of a sodium bromide and a hypochlorous acid and a sulfamic acid compound . Further, it is not clear what kind of compound is formed as the "reaction product of bromine and sulfamic acid compound", but it is considered that "bromosulfamic acid" which is a hypobromic acid stabilizing compound is produced.

By these methods, it is possible to reduce the content of the trihalomethanes in the permeated water while suppressing the slime of the separation membrane in the membrane separation apparatus using the feed water or the cleansing water containing the trihalomethane precursor. In addition, film contamination due to microorganisms can be reliably suppressed without substantially deteriorating the performance of the separation membrane. By the slime suppression method of the separation membrane according to the present embodiment, it is possible to perform the slime suppression treatment which suppresses the influence on the membrane performance and the downstream water quality to the minimum while having the high slime suppression effect.

The bromine-based oxidizing agent and the hypobromic acid stabilizing composition, like the chlorine-based oxidizing agent, react with the trihalomethane precursor to produce the trihalomethane, but the trihalomethane and the trihydrohalogen compound, which is produced by the hypobromic acid stabilizing composition, Methane is mostly bromine-based trihalomethanes such as bromoform, and it is easier to exclude chlorine-based trihalomethane such as chloroform produced by a chlorine-based oxidizer by the separation membrane, Methane is considered to be greatly reduced. The reason why the rejection rate due to the separation membrane of the bromine-based trihalomethane is high is unclear in detail, but it is presumed that the bromine-based trihalomethane has a relatively large molecular weight as compared with the chlorine-based trihalomethane.

As described above, although the slime suppressing method according to the present embodiment exhibits a slime suppressing effect equal to or higher than that of the chlorine-based oxidizing agent such as hypochlorous acid, the method of suppressing slime in the separating membrane of the produced bromine- The rejection rate of the separation membrane is remarkably high, so that the trihalomethane in the permeated water of the separation membrane can be greatly reduced. Therefore, the slime inhibitor used in the slime suppressing method of the separation membrane according to the present embodiment is suitable as a slime inhibitor for a separation membrane.

Among the slime suppressing methods of the separator according to the present embodiment, there are a method in which "bromine-based oxidizing agent" and "sulfamate compound" are present, a method in which "reaction product of bromine compound and chlorine oxidizer" and "sulfamate compound" A reaction product of a bromine-based oxidizing agent and a sulfamic acid compound " or a " reaction product of a bromine compound and a chlorine-based oxidizing agent and a reaction product of a sulfamic acid compound " is remarkably low, The slime can be inhibited by flowing directly into the membrane. Therefore, the slime inhibitor used in the slime suppressing method is more suitable as a slime inhibitor for the separation membrane.

When the bromine-based oxidizing agent or the "reaction product of the bromine compound and the chlorine-based oxidizing agent" in the separation membrane slime suppressing method according to the present embodiment is bromine, the chlorine-based oxidizing agent is not present. Therefore, The amount of the trihalomethanes produced is also lowered, which is more suitable as a slime inhibitor for separators. When a chlorine-based oxidizing agent is included, generation of chloric acid is a concern.

The trihalomethanes refer to those in which three hydrogen atoms of methane are substituted with a halogen, for example, chloroform, bromodichloromethane, dibromochloromethane and bromoform. The trihalomethane precursor may be a precursor of the trihalomethane and is not particularly limited. For example, a compound having a 1,3-diketone structure, a 1,3-dihydroxybenzene structure, And compounds which can be used in the present invention. Specific examples of the trihalomethane precursor include humic acid including humic acid and fulvic acid, and the like. Here, humic substances (corrosive substances) are organic components formed by corrosion of parts such as leaves and stalks of plants. Fumaric acid and fractions which do not precipitate are called fulvic acid.

The trihalomethane precursor can be measured by a measurement method based on the "Law Concerning the Conservation of Water Quality in Water and Sewage Areas for the Prevention of Specific Water Deposition (THMFP) (mg / l)" have. Specifically, under the condition that sodium hypochlorite is added so that the concentration of the free residual chlorine after the sample is pH 7.0, temperature 20 ° C, reaction time 24 hours and 24 hours is 1 to 2 mg / liter, the produced trihalomethane And the production amount is determined by the method of the crude analysis by a purge-trap gas chromatography mass spectrometer. In addition, the trihalomethane precursor can also be measured by a TOC system or the like.

When the trihalomethane precursor is present in an amount of 0.001 mg / L or more as the trihalomethane generating capacity (THMFP) (mg / L), the trihalomethane is likely to be produced. Therefore, Is more than or equal to 0.001 mg / liter, preferably 0.01 mg / liter or more, more preferably 0.02 mg / liter or more, the slime suppressing method according to the present embodiment is more effective . There is no particular limitation on the upper limit of the ability of the trihalomethanes to generate water in the membrane separator or the washing water, but it is, for example, 1 mg / liter or less.

Further, when the trihalomethane precursor is present at a concentration of 0.5 mg / L or more as TOC, a trihalomethane is likely to be produced. Therefore, TOC of water or washing water to the membrane separator is preferably 0.5 mg / L or more, Is 5.0 mg / L or more, and more preferably 10.0 mg / L or more, the slime suppression method of the separation membrane according to the present embodiment is more effective. The upper limit of the TOC of the water feed or washing water to the membrane separation apparatus is not particularly limited, but is, for example, 500 mg / liter or less. Further, when measured in Examples described later, the trihalomethane-producing ability of 0.01 mg / L corresponds to 5.0 mg / L of TOC.

In particular, when the trihalomethane precursor contains a hush acid, if the hyaluronic acid is present in an amount of 0.89 mg / L or more, a trihalomethane is likely to be formed. Therefore, the fumed acid in the water supply or washing water to the membrane separator is 0.89 mg / L or more, preferably 8.9 mg / L or more, and more preferably 890 mg / L or more, the slime suppression method of the separator according to the present embodiment is more effective. There is no particular limitation on the upper limit of the amount of the humic acid in the feed water or the washing water to the membrane separator, but it is, for example, 180 mg / liter or less. In addition, when measured in the examples described later, the trihalomethane-producing ability of 0.01 mg / L corresponds to 8.9 mg / L of humic acid.

In the method of suppressing slime of the separation membrane according to the present embodiment, the effect is more exerted when the water supply or washing water to the membrane separation apparatus including the separation membrane further contains bromide ions. According to the slime suppressing method of the separation membrane according to the present embodiment, in the membrane separating apparatus using the feed water or the cleansing water containing the bromine ion and the trihalomethane precursor, the membrane separation apparatus having sufficient slime suppression effect, The content of halomethane can be reduced.

As described above, when a chlorine-based oxidizing agent such as hypochlorous acid is added to water containing a trihalomethane precursor, a trihalomethane such as chloroform is produced. However, when bromine ions are contained in water such as sea water For example, 5 mg / L or more) and at the same time contains a trihalomethane precursor such as a humic acid, the addition of hypochlorous acid as a slime inhibitor produces a bromine-based trihalomethane. Since the bromine-based trihalomethane has a molecular weight larger than that of the chlorine-based trihalomethane, the total trihalomethane concentration becomes large.

The slime inhibitor such as " hypobromic acid " used in the slime suppressing method of the separator according to the embodiment of the present invention and " hypobromic acid stabilizing composition having bromine-based oxidizer and sulfamic acid coexist " (Sterilization effect) is demonstrated. In addition, when a trihalomethane precursor and bromide ion are present in the system, they mainly produce bromine based trihalomethanes. However, unlike conventional hypochlorous acid, these "hypochloric acid" and "hypochloric acid stabilizing composition" rarely increase the amount of the trihalomethane produced along with the increase of the bromide ion concentration. Therefore, according to the slime suppression method of the separator according to the present embodiment using a slime inhibitor such as " hypobromic acid " or " hypobromic acid stabilizing composition in which bromine-based oxidizing agent and sulfamic acid coexist " It is considered that the concentration of the produced trihalomethane is lower than that in the case of using hypochlorous acid.

On the other hand, since the "stabilized hypochlorous acid" such as chlorosulfamic acid is stabilized, the trihalomethane generating ability is suppressed, but the sterilizing power is lower than that of "hypochloric acid" or "hypochloric acid stabilizing composition" The effect is not obtained.

Although the slime inhibitor used in the slime suppressing method of the separation membrane according to the present embodiment exhibits a slime suppressing effect equal to or higher than that of hypochlorous acid, when bromide ions are contained in the water to be treated, compared with hypochlorous acid, The amount of trihalomethanes produced is small. Therefore, the slime suppression method of the separation membrane according to the present embodiment is suitable as a slime suppression method of a membrane separation apparatus using feed water or cleansing water containing a bromide ion and a trihalomethane precursor.

As described above, the slime suppression method of the separation membrane according to the present embodiment has a high slime suppression effect, and it is possible to perform the slime suppression treatment in which the concentration of the trihalomethane in the permeated water of the separation membrane is minimized.

Particularly, when bromine ions are present in an amount of 5 mg / L or more in the feed water or washing water to the membrane separator, trihalomethanes tend to be formed in the case of hypochlorous acid. Therefore, If the concentration of ions is 5 mg / liter or more, preferably 18 mg / liter or more, the slime suppression method of the separation membrane according to the present embodiment is more effective. There is no particular limitation on the upper limit of the concentration of bromide ions in the water feed or washing water to the membrane separation apparatus, but it is, for example, 1000 mg / liter or less.

In the method of suppressing slime of the separation membrane according to the present embodiment, for example, a method in which a "bromine-based oxidizing agent" or "bromine-based oxidizing agent" is added to water or washing water in a membrane separation apparatus using feed water or cleaning water containing a trihalomethane precursor Reaction product of the chlorine-based oxidizing agent and the chlorine-based oxidizing agent "may be injected by a drug injection pump or the like. The " bromine compound " and " chlorine-based oxidizing agent " may be separately added to the aqueous system or may be added to the aqueous system after mixing the undiluted solutions.

For example, in a water supply or cleaning water to a membrane separation apparatus using a feed water or a cleansing water containing a trihalomethane precursor, a "bromine-based oxidizer" or "a reaction product of a bromine compound and a chlorine-based oxidizer" Sulfamic acid compound "may be injected by a drug injection pump or the like. The "bromine-based oxidizing agent" or "the reaction product of the bromine compound and the chlorine-based oxidizing agent" and the "sulfamic acid compound" may be separately added to the aqueous system or may be added to the aqueous system after mixing the undiluted solutions.

Further, it is also possible to use, for example, a reaction product of a bromine-based oxidizing agent and a sulfamic acid compound, or a reaction product of a bromine-containing oxidizing agent and a sulfamic acid compound in water or washing water to a membrane separation apparatus using a feed water or a cleansing water containing a trihalomethane precursor A reaction product of a chlorine-based oxidizing agent and a sulfamic acid compound " may be injected by a drug injection pump or the like.

The aforementioned slime inhibitor added to the feed water or washing water to the membrane separator may be decomposed by a reducing agent or the like immediately before the separation membrane.

With the slime suppression method of the separation membrane according to the present embodiment, deterioration of the separation membrane can be suppressed even in the membrane separation system that performs operation and stop operation, and the separation membrane can be effectively sterilized during operation stop.

<Membrane Separation System>

An outline of an example of a membrane separation system according to an embodiment of the present invention is shown in Fig. 1, and the structure thereof will be described. The membrane separation system (1) includes a raw water tank (10) and a membrane separation device (12).

In the membrane separation system 1 of Fig. 1, a raw water pipe 16 is connected to the inlet of the raw water tank 10. The outlet of the raw water tank 10 and the inlet of the membrane separator 12 are connected by a raw water supply pipe 18 via a pump 14. A permeated water pipe 20 is connected to the permeate water outlet of the membrane separation device 12, and a concentrated water pipe 22 is connected to the concentrated water outlet. A sterilizing agent supply pipe 24 is connected between the pump 14 and the inlet of the membrane separation device 12 in the raw water supply pipe 18.

The operation of the membrane separation system 1 according to the present embodiment and the method of sterilizing the separation membrane will be described.

The raw water to be treated is stored in the raw water tank 10 as needed and then supplied to the membrane separation device 12 through the raw water supply pipe 18 by the pump 14. In the membrane separator 12, a membrane separation process is performed by a separation membrane (membrane separation process step). The permeated water (treated water) obtained by the membrane separation treatment is discharged through the permeated water pipe 20, and the concentrated water is discharged through the concentrated water pipe 22. The concentrated water may be circulated in the raw water tank 10 or the raw water supply pipe 18.

A sterilizing agent supply mechanism may be provided between the pump 14 in the raw water supply pipe 18 and the inlet of the membrane separation device 12 and the raw water in the raw water tank 10 may be supplied to the membrane separation device 12 At the same time, a predetermined concentration of the bactericide is added from the bactericide addition device to the raw water through the bactericide supply pipe 24. When the operation of the membrane separation system 1 is stopped, the pump 14 is stopped, and the sterilizing agent is present in the membrane separation apparatus 12 during the operation stop of the membrane separation system 1. The sterilizing agent supply mechanism may be provided in the raw water supply pipe 18 or the raw water tank 10.

It is also possible to feed the raw water in the raw water tank 10 to the membrane separation device 12 and add a sterilizing agent of a predetermined concentration from the bactericide addition mechanism through the bactericide supply piping 24 to the raw water, The pump 14 is stopped after the sterilizing agent of the predetermined concentration is added from the sterilizing agent addition pipe through the sterilizing agent supply pipe 24 to the raw water, and during the operation stop of the membrane separation system 1 A sterilizing agent may be present in the membrane separation apparatus 12.

Here, "stop operation" refers to a state in which no treated water (permeated water) is obtained in the membrane separation system 1.

When the membrane separation apparatus 12 is backwashed by using reverse osmosis water or using permeated water as reverse osmosis water, a sterilizing agent is added to the reverse osmosis water to remove the sterilizing agent Or may be present in the separation device 12.

In the membrane separation system 1, a level switch is provided in the raw water tank 10, and when the level in the raw water tank 10 detected by the level switch at the time of operation becomes lower than a predetermined height, the operation is stopped, The operation may be resumed when the water level in the raw water tank 10 detected by the level switch becomes higher than a predetermined height.

The slime suppression method of the separation membrane according to the present embodiment is a method of separating "bromine-based oxidizing agent" and "sulfamate compound" as a bactericide (slime inhibitor) during the operation stop of the membrane separation system 1 in which operation and operation stop are performed Or a reaction product of a bromine compound and a chlorine-based oxidizing agent and a sulfamate compound in a membrane separator 12. The method of the present invention is not particularly limited, By this, it is considered that the hypobromic acid stabilizing composition is produced in the sterilizing agent-containing water or the bactericide-containing water.

The method of suppressing the slime of the separation membrane according to the present embodiment is a method in which the reaction product of a bromine-based oxidizing agent and a sulfamic acid compound as a bactericide (slime inhibitor) during the operation stop of the membrane separation system 1, Or a &quot; reaction product of a bromine compound and a chlorine-based oxidizing agent, and a reaction product of a sulfamic acid compound &quot;, is applied to the membrane separator 12, .

Concretely, the slime suppression method of the separation membrane according to the present embodiment is characterized in that, during the operation stoppage of the membrane separation system 1 in which the operation and the operation stop are performed, for example, "bromine", "bromine chloride" Bromic acid &quot; or &quot; a reaction product of sodium bromide and hypochlorous acid &quot; and &quot; sulfamic acid compound &quot;

The method of suppressing the slime of the separation membrane according to the present embodiment is a method for suppressing the slime of the separation membrane according to the present invention, for example, during the operation stoppage of the membrane separation system 1 in which the operation and the operation stop are performed, A reaction product of bromine and a sulfamic acid compound "or" a reaction product of sodium bromide and hypochlorous acid and a sulfamic acid compound "is present in the membrane separation apparatus 12.

By these methods, deterioration of the separation membrane of the membrane separation device 12 can be suppressed in the membrane separation system 1 that performs the operation and the operation stop, and the separation membrane can be effectively sterilized during the operation stop. In addition, there is no need for complicated additional equipment for periodically supplying the sterilizing agent, thus simplifying the system.

In the slime suppression method of the separation membrane according to the present embodiment, for example, during the operation stoppage of the membrane separation system 1 in which the operation and the operation stop are performed, the "bromine-based oxidizer" or "the reaction product of the bromine compound and the chlorine- , &Quot; sulfamic acid compound &quot; may be injected into the aqueous system by a drug injection pump or the like. The "bromine-based oxidizing agent" or "the reaction product of the bromine compound and the chlorine-based oxidizing agent" and the "sulfamic acid compound" may be separately added to the aqueous system or may be added to the aqueous system after mixing the undiluted solutions.

Further, for example, during the operation stoppage of the membrane separation system 1 in which the operation and the operation stop are carried out, the reaction product of the bromine compound and the chlorine-based oxidizer and the reaction product of the bromine-based oxidizing agent and the sulfamic acid compound, Reaction product of the compound &quot; may be injected into the aqueous system by a drug injection pump or the like.

In the slime suppression method of the separation membrane according to the present embodiment, the ratio of the equivalence of the "sulfamic acid compound" to the equivalent of "bromine-based oxidizer" or "reaction product of bromine compound and chlorine-based oxidizer" More preferably in a range of 1 or more and 2 or less. If the equivalent ratio of the "bromine-based oxidizing agent" or "reaction product of the bromine compound and chlorine-based oxidizing agent" to the equivalent amount of the "sulfamic acid compound" is less than 1, there is a possibility of deteriorating the film. have.

The effective halogen concentration in contact with the separation membrane is preferably 0.01 to 100 mg / liter in terms of effective chlorine concentration. If it is less than 0.01 mg / L, a sufficient slime inhibiting effect may not be obtained. If it is more than 100 mg / L, deterioration of the separation membrane and corrosion of piping and the like may occur.

Examples of the bromine-based oxidizing agent include bromine (liquid bromine), bromine chloride, bromine acid, bromate, and hypobromic acid.

Among them, the preparation of "a reaction product of bromine and a sulfamic acid compound (mixture of bromine and sulfamic acid compound)" or "a reaction product of bromine and a sulfamic acid compound" using bromine is described in "Preparation of hypochlorous acid and a bromine compound and (RO membrane) without further deteriorating the reverse osmosis membrane (RO membrane) or the like, as compared with the formulation of "fumaric acid" and the preparation of "bromamine chloride and sulfamic acid" It is more preferable to use a slime inhibitor for a separator such as a reverse osmosis membrane (RO membrane) because the amount of effective halogen leakage to membrane permeated water such as permeated water is less.

That is, the slime suppression method of a separation membrane according to an embodiment of the present invention is characterized in that bromine and a sulfamic acid compound are present in water or washing water in a membrane separation apparatus containing a separation membrane containing a trihalomethane precursor (In which a mixture of bromine and sulfamic acid compound is present). It is also desirable to have a reaction product of bromine and a sulfamic acid compound present in the water or washing water in a membrane separation apparatus containing a separating membrane containing a trihalomethane precursor.

Examples of the bromine compound include sodium bromide, potassium bromide, lithium bromide, ammonium bromide, and hydrobromic acid. Of these, sodium bromide is preferable in terms of preparation cost and the like.

Examples of the chlorine-based oxidizing agent include chlorine gas, chlorine dioxide, hypochlorous acid or its salt, chlorous acid or its salt, chloric acid or its salt, perchloric acid or its salt, chlorinated isocyanuric acid or its salt . Among them, examples of the salt include alkali metal hypochlorite such as sodium hypochlorite, potassium hypochlorite and the like, hypochlorous acid alkaline earth metal salts such as calcium hypochlorite and barium hypochlorite, alkali metal chlorides such as sodium chlorite and potassium hypochlorite , Alkali earth metal chlorides such as sodium chlorite and barium chlorite, other metal chlorites such as nickel chlorite, alkali metal chlorides such as ammonium chlorate, sodium chlorate and potassium chlorate, and alkaline earth metal chlorides such as calcium chlorate and barium chlorate. . These chlorine-based oxidizing agents may be used singly or in combination of two or more kinds. As the chlorine-based oxidizing agent, it is preferable to use sodium hypochlorite in view of handleability and the like.

The sulfamic acid compound is a compound represented by the following general formula (1):

R ₂ NSO ₃ H (1)

Wherein R is independently a hydrogen atom or an alkyl group having 1 to 8 carbon atoms.

As the sulfamic acid compound, for example, sulfamic acid (amide sulfuric acid) in which two R groups are hydrogen atoms, as well as N-methylsulfamic acid, N-ethylsulfamic acid, N-propylsulfamic acid, Sulfamic acid, N, N-dimethylsulfamic acid, N, N-diethyl (meth) acrylamide, sulfamic acid compounds in which one of the two R groups, Two R groups such as sulfamic acid, N, N-dipropylsulfamic acid, N, N-dibutylsulfamic acid, N-methyl-N-ethylsulfamic acid and N- A sulfamic acid compound in which one of two R groups such as a sulfamic acid compound having a number of 1 to 8 and N-phenylsulfamic acid is a hydrogen atom and the other is an aryl group having 6 to 10 carbon atoms, . Examples of sulfamates are alkali metal salts such as sodium salts and potassium salts, alkaline earth metal salts such as calcium salts, strontium salts and barium salts, manganese salts, copper salts, zinc salts, iron salts, cobalt salts and nickel salts Other metal salts, ammonium salts, and guanidine salts. The sulfamic acid compound and salts thereof may be used singly or in combination of two or more kinds. As the sulfamic acid compound, sulfamic acid (amide sulfuric acid) is preferably used in terms of environmental load and the like.

In the slime suppressing method of the separation membrane according to the present embodiment, alkali may be further present. Examples of the alkali include alkali hydroxides such as sodium hydroxide and potassium hydroxide. Sodium hydroxide and potassium hydroxide may be used in combination in view of the stability of the product at low temperatures and the like. Further, the alkali may be used not as a solid but as an aqueous solution.

Examples of the separation membrane include a reverse osmosis membrane (RO membrane), a nanofiltration membrane (NF membrane), a microfiltration membrane (MF membrane), and an ultrafiltration membrane (UF membrane). Among them, the slime suppression method of the separation membrane according to the embodiment of the present invention can be suitably applied to the reverse osmosis membrane (RO membrane) in particular. In addition, the slime suppression method of the separation membrane according to the embodiment of the present invention can be appropriately applied to the polyamide-based polymer membrane which is the mainstream as the reverse osmosis membrane. The polyamide-based polymer membrane has a relatively low resistance to an oxidizing agent, and if the free chlorine or the like is continuously brought into contact with the polyamide-based polymer membrane, the membrane performance is remarkably lowered. However, in the method of suppressing the slime of the separator according to the present embodiment, such a remarkable deterioration of the membrane performance hardly occurs even in the polyamide polymer membrane.

In the slime suppression method of the separation membrane according to the present embodiment, in the case of the RO apparatus in which the membrane separation apparatus includes the reverse osmosis membrane (RO membrane) as the separation membrane, the pH of water supplied to the RO apparatus is preferably 5.5 or more, More preferably at least 6.5, and still more preferably at least 6.5. If the pH of the water supplied to the RO device is less than 5.5, the permeation amount may decrease. The upper limit value of the pH of the water supplied to the RO device is not particularly limited as far as the upper limit of the applied reverse osmosis membrane (RO membrane) is applied (for example, pH 10). However, It is preferable that the pH is, for example, 9.0 or less. When the slime suppressing method according to the present embodiment is used, the deterioration of the reverse osmosis membrane (RO membrane) and deterioration of the water quality of the treated water (permeated water) It is possible to secure sufficient permeation water while exhibiting a sufficient slime suppressing effect.

In the RO device, when the water supply to the RO device occurs at a pH of 5.5 or higher, a dispersant may be used in combination with a bromine-based oxidizing agent or a hypobromous acid stabilizing composition for scale inhibition. Examples of the dispersing agent include polyacrylic acid, polymaleic acid, and phosphonic acid. The addition amount of the dispersing agent to the feed water is, for example, in the range of 0.1 to 1,000 mg / l as the concentration in the RO concentrated water.

In order to suppress the generation of scale without using a dispersant, for example, it is preferable that the concentration of silica in the RO concentrated water is made to be equal to or less than the solubility and the Langelier index, which is an index of calcium scale, And the like, and the like.

Examples of applications of the RO apparatus include desalination of seawater, drainage of water, and the like.

&Lt; Slime inhibitor composition for separation membrane &

The slime inhibitor composition for a separation membrane according to the present embodiment contains a "bromine-based oxidizing agent" or "a reaction product of a bromine compound and a chlorine-based oxidizing agent" and a "sulfamic acid compound" and may further contain an alkali.

The slime inhibitor composition for a separator according to the present embodiment contains the reaction product of a bromine-based oxidizing agent and a sulfamic acid compound or the reaction product of a bromine compound and a chlorine-based oxidizing agent and a sulfamic acid compound, And may further contain an alkali.

The bromine-based oxidizing agent, the bromine compound, the chlorine-based oxidizing agent and the sulfamic acid compound are as described above.

The slime inhibitor composition for a separator according to the present embodiment is advantageous in that it does not further deteriorate the reverse osmosis membrane (RO membrane) or the like and has less leakage of effective halogens to permeate water such as RO permeated water, (Containing a mixture of bromine and a sulfamic acid compound), for example, a mixture of a bromine and a sulfamic acid compound, a mixture of an alkali and water, or a reaction product of a bromine and a sulfamic acid compound For example, a reaction product of bromine and a sulfamic acid compound, and a mixture of an alkali and water are preferable.

Although the slime inhibitor composition for separation membrane according to the present embodiment has a higher oxidative power and a remarkably higher slime deterrent and slime peel strength than the binding chlorinated slime inhibitor such as chlorosulfamic acid and the like, There is almost no possibility of causing remarkable film deterioration. The effect on the film deterioration can be substantially ignored at the normal use concentration. Therefore, it is optimal as a slime inhibitor for a separator such as a reverse osmosis membrane (RO membrane).

Unlike the hypochlorous acid, the slime inhibitor composition for separation membrane according to the present embodiment scarcely influences the reverse osmosis membrane (RO membrane), so that it hardly affects the quality of treated water. In addition, since the concentration can be measured in the field like hypochlorous acid, more accurate concentration control is possible. In addition, the slime inhibitor composition for a separation membrane according to the present embodiment reacts with a trihalomethane precursor to produce a bromine-based trihalomethane, but is easily excluded by the separation membrane, Methane is considered to be greatly reduced.

The pH of the composition is, for example, more than 13.0 and more preferably more than 13.2. If the pH of the composition is 13.0 or less, the effective halogen in the composition sometimes becomes unstable.

The concentration of bromic acid in the slime inhibitor composition for separator is preferably less than 5 mg / kg. If the concentration of bromic acid in the slime inhibitor composition for separation membrane is 5 mg / kg or more, the concentration of bromate ions in the permeate water may be increased.

&Lt; Preparation method of slime inhibitor composition for separation membrane &

The slime inhibitor composition for a separation membrane according to the present embodiment may be obtained by mixing a bromine-based oxidizing agent and a sulfamic acid compound, or by mixing a reaction product of a bromine compound and a chlorine-based oxidizing agent with a sulfamic acid compound, .

As a method for producing a slime inhibitor composition for a separation membrane containing bromine and a sulfamic acid compound or a slime inhibitor composition for a separation membrane containing a reaction product of bromine and a sulfamic acid compound, a mixed solution containing water, an alkali and a sulfamic acid compound Adding bromine to the mixed solution containing water, an alkali, and a sulfamic acid compound under an inert gas atmosphere, or a step of adding bromine to the mixed solution containing water, an alkali and a sulfamic acid compound under an inert gas atmosphere. When the reaction is carried out in an inert gas atmosphere or under an inert gas atmosphere, the bromate ion concentration in the composition is lowered and the bromate ion concentration in the permeated water such as RO permeated water is lowered.

The inert gas to be used is not particularly limited, but at least one of nitrogen and argon is preferable in terms of production and the like, and nitrogen is particularly preferable in view of production cost and the like.

The concentration of oxygen in the reactor during the addition of bromine is preferably 6% or less, more preferably 4% or less, still more preferably 2% or less, and particularly preferably 1% or less. When the oxygen concentration in the reactor at the time of bromine reaction exceeds 6%, the amount of bromic acid produced in the reaction system sometimes increases.

The addition amount of bromine is preferably 25% by weight or less, more preferably 1% by weight or more and 20% by weight or less based on the total amount of the composition. When the addition ratio of bromine exceeds 25 wt% with respect to the total amount of the composition, the amount of bromic acid produced in the reaction system sometimes increases. If it is less than 1% by weight, the sterilizing power may be lowered.

The reaction temperature at the time of bromine addition is preferably controlled in the range of 0 占 폚 to 25 占 폚, but more preferably in the range of 0 占 폚 to 15 占 폚 in terms of production cost and the like. If the reaction temperature at the time of bromine addition exceeds 25 DEG C, the amount of bromic acid produced in the reaction system sometimes increases. If the reaction temperature is lower than 0 DEG C, it may be frozen.

Example

Hereinafter, the present invention will be described in more detail with reference to Examples and Comparative Examples, but the present invention is not limited to the following Examples.

In the case of using a hypobromic acid stabilizing composition "a reaction product of a bromine-based oxidizing agent and a sulfamic acid compound" (Example 1) as a slime inhibitor, a "reaction product of a bromine compound and a chlorinated oxidizing agent and a reaction product of a sulfamic acid compound" (Example 3) in the case of using the bromine acid stabilizing composition (Example 2), the case of using the "bromine-based oxidizing agent" (Example 3) and the case of using hypochlorous acid as the general slime inhibitor (Comparative Example 1) Phosphorus concentration, and reverse osmosis membrane (RO membrane) performance.

[Preparation of composition 1]

Composition 1 was prepared by mixing 16.9 wt% of liquid bromine, 10.7 wt% of sulfamic acid, 12.9 wt% of sodium hydroxide, 3.94 wt% of potassium hydroxide and 3.94 wt% of water, in a nitrogen atmosphere. The pH of the composition 1 was 14, and the effective halogen concentration (effective chlorine conversion concentration) was 7.5% by weight. The detailed preparation method of the composition 1 is as follows.

1436 g of water and 361 g of sodium hydroxide were added to a 2 L four-necked flask sealed with continuous injection while the flow rate of nitrogen gas was controlled by a mass flow controller so that the oxygen concentration in the reaction vessel was maintained at 1% Then, 300 g of sulfamic acid was added and mixed. Then, 473 g of liquid bromine was added while maintaining the temperature of the reaction solution at 0 to 15 캜, and furthermore, 230 g of a 48% potassium hydroxide solution was added, To obtain a desired composition 1 having a sulfamacic acid content of 10.7%, bromine content of 16.9% and an equivalent ratio of sulfamic acid to bromine equivalent of 1.04. The pH of the resulting solution was 14 as measured by a glass electrode method. The bromine content in the resulting solution was 16.9% as measured by the redox titration method using bromine in the form of potassium iodide and sodium thiosulfate, which was 100.0% of the theoretical content (16.9%) . The oxygen concentration in the reaction vessel during the bromine reaction was measured using "Oxygen Monitor JKO-02LJDII" manufactured by Jikco Ltd. In addition, the concentration of bromic acid was less than 5 mg / kg.

[Preparation of Composition 2]

Composition 2 was prepared by mixing 11 wt% sodium bromide, 12 wt% sodium hypochlorite aqueous solution, 50 wt% sodium sulfamate, 8 wt% sodium hydroxide, and 8 wt% water. The pH of the composition 2 was 14, and the effective halogen concentration (effective chlorine concentration) was 6% by weight. The detailed preparation method of the composition 2 is as follows.

17 g of water was added to the reaction vessel, and 11 g of sodium bromide was added to the solution and stirred to dissolve the mixture. 50 g of a 12% aqueous solution of sodium hypochlorite was added and mixed. 14 g of sodium sulfamate was then added and stirred to dissolve. Sodium hydroxide was added and dissolved by stirring to obtain the desired composition 2.

The content of chloric acid in the composition was smaller than that of the composition 2 (1100 mg / kg) by one method in accordance with the method specified in the sodium hypochlorite standard for drinking water (JWWA K 1202008) / Kg).

[Composition 3]

A 9 wt% sodium hypochlorite aqueous solution (product of Kanto Chemical Co., Inc., Cica I grade) was used as Composition 3.

[Composition 4]

A 12 wt% sodium hypochlorite aqueous solution was used as Composition 4.

&Lt; Examples 1 to 3, Comparative Example 1, Reference Examples 1 and 2 >

Compositions 1 to 4 were respectively added to the raw water of the reverse osmosis membrane device under the following conditions to determine the total concentration of the trihalomethane in the feed water of the separation membrane and permeate permeated membrane and the concentration of the total trihalomethane in the reverse osmosis membrane (RO membrane) Were compared. As the raw water, the following simulations were used in Examples 1 to 3 and Comparative Example 1, and pure water was used in Reference Examples 1 and 2.

(Exam conditions)

· Tester: Flat Tester

Separation membrane: Nitto Denko Corporation, a polyamide-based polymer reverse osmosis membrane ES15

Operating pressure: 0.75MPa

Raw water: Simulated water having a trihalomethane production capacity of 0.01 mg / l (8.9 mg / l of pure water as a precursor of hush acid (manufactured by Wako Pure Chemical Industries, Ltd.) as a trihalomethane precursor) Added, TOC: 5 mg / l) or pure water

Agent: The composition 1 to 4 was added so as to have an effective halogen concentration (effective chlorine conversion concentration) of 3 mg / l

· Raw water pH: The pH of test water is adjusted to 8 after the addition of drug.

· Test temperature: 25 ℃

- Method for measuring the trihalomethane generating ability: A sample was prepared by adding sodium hypochlorite so that the concentration of the free residual chlorine after the reaction was 24 hours and 24 hours at pH 7.0, 20 ° C, and 1 to 2 mg / The amount of produced trihalomethanes was determined by the method of the crude analysis by a purge-trap gas chromatography mass spectrometer. Agilent Technologies, Inc., 7890 "for gas chromatography and" Agilent product, 5975C "for mass spectrometry are used for the fuzzy trap device" TEKMAR Stratum "by Teledyne Tekmar Inc. Respectively.

Method for Measuring Effective Halogen Concentration: Measurement by a DPD method using a residual chlorine measuring device (product of Hach Company, "DR-4000")

(Assessment Methods)

[Total trihalomethane concentration in RO water and RO permeate water, rejection rate of total trichloromethane by reverse osmosis membrane (RO membrane)] [

The simulated water or purified water was added with Composition 1 to 4 as shown in Table 1 and the pH was adjusted to 8. The water temperature was adjusted to 25 캜 and circulated and circulated in the RO device. After 4 hours, the total concentration of trihalomethanes (mg / l) in RO water and RO permeate was measured. From the total trichloromethane concentration in the RO water and the RO permeate, the rejection rate (%) of the total trichloromethane by the reverse osmosis membrane (RO membrane) was calculated. The results are shown in Table 1. Wherein the total trihalomethanes refer to the four materials chloroform, bromodichloromethane, dibromochloromethane and bromoform.

The concentration of total trihalomethanes was determined by the method of Japanese traditional method by purge-trap gas chromatography mass spectrometry according to the method prescribed by the Minister of Health, Labor and Welfare (2003 Ministry of Health, Labor and Welfare Notice No. 261) Respectively.

drugs
Number of Tests Total trihalomethane concentration
(Mg / l) Excretion rate of total trihalomethanes by RO membrane (%) RO grade
(After drug addition) RO permeability
(After drug addition) Example 1 Composition 1 Mock number 0.022 <0.001 > 95 Example 2 Composition 2 Mock number 0.042 <0.001 > 95 Example 3 Composition 3 Mock number 0.036 <0.001 > 95 Comparative Example 1 Composition 4 Mock number 0.005 0.002 60 Comparative Example 2 Composition 1 pure <0.001 <0.001 - Comparative Example 3 Composition 4 pure <0.001 <0.001 -

As described above, in Examples 1 to 3, the content of the trihalomethanes in the permeated water could be reduced while having a sufficient slime suppressing effect as compared with Comparative Example 1. Further, in the case of Reference Examples 1 and 2 using pure water as the raw water, almost no trihalomethane was produced.

&Quot; Influence on rejection rate of reverse osmosis membrane (RO membrane), effect on permeated water, comparative test of oxidizing power &quot;

The effect of the bromine-based oxidizing agent, the reaction product of the bromine compound and the chlorine-based oxidizing agent, the case of using the sulfamic acid compound, and the rejection rate of the reverse osmosis membrane (RO membrane) when hypochlorous acid and hypobromic acid, which are general slime inhibitors, The effect on permeation water, the oxidizing power and the sterilizing power were compared.

Compositions 1, 2 and 4 to 7 were added to the raw water of the reverse osmosis membrane device under the following conditions to compare the effect on the rejection rate of the reverse osmosis membrane (RO membrane), the effect on the permeated water and the oxidizing power.

[Composition 5]

Each composition of Composition 2 was added separately in water.

[Composition 6]

Composition 6 containing bromine chloride, sodium sulfamate and sodium hydroxide was used. The pH of the composition 6 was 14, and the effective halogen concentration (effective chlorine concentration) was 7% by weight.

[Composition 7]

15% by weight of sodium bromide, and 42.4% by weight of a 12% sodium hypochlorite aqueous solution were added separately to water.

(Exam conditions)

· Tester: Flat Tester

Membrane: Polyamide-based polymer reverse osmosis membrane ES20 (manufactured by Nitto Denko Co., Ltd.)

Operating pressure: 0.75MPa

· Raw water: Sagamihara well (pH 7.2, conductivity 240 μS / cm, bromide ion concentration less than 1.0 mg / l)

Pharmaceutical agent: The compositions 1, 2 and 4 to 7 were added so as to have an effective halogen concentration (effective chlorine conversion concentration) of 10 mg / l

(Assessment Methods)

· Effect on rejection rate of reverse osmosis membrane (RO membrane): Conductivity rejection rate (%) after 30 days water flow

(100 - [Permeation Water Conductivity / Water Conductivity] x 100)

Influence on permeated water: The effective halogen concentration (effective chlorine conversion concentration, mg / l) in the permeated water 1 hour after the addition of the drug was measured using a residual chlorine measuring device ("DR-4000" Measured by

Oxidation power: The oxidation-reduction potential (ORP) of the water supply after 1 hour was measured using an oxidation-reduction potential meter (product of DKK-TOA Corporation, RM-20P type ORP system)

&Quot; Sterility Test &quot;

Compositions 1, 2 and 4 to 7 were added to the simulated water under the following conditions to compare the sterilizing power.

(Exam conditions)

· Water: Sagamihara A simulated water adjusted to have a normal bacterial count of 10 ⁵ CFU / ml by adding normal bouillon to the well

(Method for Measuring Effective Halogen Concentration: Residual chlorine measuring device (manufactured by Hach, "DR-4000", available from Hach Co., Ltd.) Quot;) measured by the DPD method)

(Assessment Methods)

The number of normal bacteria after 24 hours from the addition of the drug was measured using a bacterial counting kit (San-Ai Oil Co., Ltd., Biochecker TTC)

The test results are shown in Table 2.

RO exclusion rate
(After 30 days of water) (%) RO permeated water
Effective Halogen Concentration (mg / l) ORP
(㎷) 24 hours later
Bacteria (CFU / ml) Composition 1 99 <0.01 650 <10 ³ Composition 2 92 0.5 620 <10 ³ Composition 5 90 1.0 660 <10 ³ Composition 6 97 0.2 630 <10 ³ Composition 4 71 5.5 790 <10 ³ Composition 7 70 2.0 800 <10 ³

Compositions 1, 2, 5, and 6 had a high reverse osmosis membrane (RO membrane) rejection rate, low effective halogen concentration (effective chlorine conversion concentration) of permeated water, and high oxidizing and sterilizing power. Among Composition 1, 2, 5 and 6, Composition 1 had the highest rejection rate of the reverse osmosis membrane (RO membrane) and the lowest effective halide concentration (effective chlorine conversion concentration) of permeate water was lowest.

Composition 4 exhibited high oxidizing power and sterilizing power, but the rejection rate of the reverse osmosis membrane (RO membrane) was lowered and the effective halogen concentration (effective chlorine conversion concentration) of permeated water was also high. Composition 7 had high oxidizing power and sterilizing power, but had a somewhat higher effective halogen concentration (effective chlorine conversion concentration) of permeated water.

&Quot; Comparative Experiment of Concentration of Bromate Ion in Permeate Water &quot;

The concentration of bromate ion in the permeated water was compared with the presence or absence of nitrogen gas purge at the time of preparing the composition.

Preparation of composition 1 '

In the same manner as in the composition 1, the composition was mixed in a nitrogen atmosphere to prepare a composition 1 (1) by mixing liquid bromine: 17 wt% (wt%), sulfamic acid: 10.7 wt%, sodium hydroxide: 12.9 wt%, potassium hydroxide: 3.95 wt% '. The pH of the composition 1 'was 14, the effective halogen concentration (effective chlorine conversion concentration) was 7.5% by weight, and the bromic acid concentration was less than 5 mg / kg.

[Preparation of composition 8]

The residue was mixed with 17.7 wt% of liquid bromine, 10.7 wt% of sulfamic acid, 12.9 wt% of sodium hydroxide, 3.95 wt% of potassium hydroxide and 3.95 wt% of water, under nitrogen atmosphere without nitrogen purge, Was prepared. The pH of the composition 8 was 14, the effective halogen concentration (effective chlorine conversion concentration) was 7.4% by weight, and the bromic acid concentration was 63 mg / kg.

(Exam conditions)

· Tester: Flat Tester

Membrane: Polyamide-based polymer reverse osmosis membrane ES20 (manufactured by Nitto Denko Co., Ltd.)

Operating pressure: 0.75MPa

· Raw water: Sagamihara well (pH 7.2, conductivity 240 μS / cm)

Agents: The compositions 1 'and 8 were added so as to have an effective halogen concentration (effective chlorine conversion concentration) of 50 mg / l

(Assessment Methods)

The bromate ion concentration of permeated water was measured by the ion chromatography post column absorbance method.

The test results are shown in Table 3.

In the water supply (㎍ / ℓ) In the permeated water (/ / l) Composition 1 ' <1 <1 Composition 8 42 One

In the composition 1 ', the bromate ion concentration in the water supply and permeated water was less than 1 / / ℓ. In the composition 8, the bromate ion concentration in the water supply and the permeated water was higher than that of the composition 1 '.

Next, in the case where a hypobromic acid stabilizing composition "a reaction product of a bromine-based oxidizing agent and a sulfamic acid compound" was used as a slime inhibitor (Example 4), a case of using a "bromine-based oxidizing agent" (Example 5) In the case of using hypochlorous acid which is an inhibitor (Comparative Example 2), the concentration of the trihalomethane in the treated water in the case of using the hypochlorous acid acid stabilizing composition "reaction product of hypochlorous acid and sulfamic acid compound" Were compared.

[Composition 9]

Composition 9 was prepared by mixing 12% sodium hypochlorite aqueous solution: 50% by weight, sulfamic acid: 10% by weight, sodium hydroxide: 8% by weight, and water: The pH of the composition 9 was 14, and the effective halogen concentration (effective chlorine conversion concentration) was 6% by weight.

&Lt; Examples 4 and 5, Comparative Examples 2 and 3 >

Compositions 1, 3 and 4 were respectively added to the raw water under the following conditions to compare the total concentration of the trihalomethane in the treated water. The following simulations were used as raw water.

(Exam conditions)

Raw water: Simulated water (8.9 mg / l of hygromic acid (manufactured by Wako Pure Chemical Industries, Ltd.) as a trihalomethane precursor in pure water) and sodium bromide (Kanto Kagaku Co., Product, special grade) so as to have a concentration of 0.1 to 300 mg / L)

Agent: The compositions 1, 3 and 4 were added so that the effective halogen concentration (effective chlorine conversion concentration) was 3 mg / l

· Raw water pH: The pH of test water is adjusted to 8 after the addition of drug.

· Test temperature: 25 ℃

Method for Measuring Effective Halogen Concentration: Measurement by a DPD method using a residual chlorine measuring device ("DR-4000", manufactured by Hach)

(Assessment Methods)

[Total trichloromethane concentration in treated water]

Compositions 1, 3 and 4 were added to the simulated water, respectively, and the pH was adjusted to 8. The mixture was adjusted to a water temperature of 25 ° C and stirred for 4 hours. After 4 hours of stirring, the total concentration of trihalomethanes (mg / l) in the treated water was measured. The results are shown in Fig. Wherein the total trihalomethanes refer to the four materials chloroform, bromodichloromethane, dibromochloromethane and bromoform.

The concentration of total trihalomethanes was determined according to the method prescribed by the Minister of Health, Labor and Welfare (2003 Ministry of Health, Labor and Welfare Notice No. 261) based on the provisions of the Holy Spirit on water quality standards. .

[Comparison test of sterilizing power]

Compositions 1 and 9 were added to the simulated water under the following conditions to compare the sterilizing power.

(Exam conditions)

Water: Sagamihara A simulated water adjusted to have a normal bacterial count of 10 ⁵ CFU / ml by adding normal water to the well

(Method for Measuring Effective Halogen Concentration: Residual chlorine measuring device (product of Hach, &quot; DR-4000 &quot;)) was added to each of the compositions 1 and 9 so as to have an effective halogen concentration (effective chlorine conversion concentration) And measured by the DPD method)

(Assessment Methods)

· The number of normal bacteria after 24 hours from the addition of the drug was measured using a bacterial counting kit (San Iseki, Bio-Checker TTC).

The test results are shown in Table 4.

Initial number of bacteria (CFU / ml) The number of bacteria after 24 hours (CFU / ml) Example 4 (Composition 1) 10 ⁵ <10 ³ Comparative Example 3 (Composition 9) 10 ⁵ 10 ⁴

As described above, in Examples 4 and 5, formation of a slurry in water containing a trihalomethane precursor and bromide ion was suppressed compared with Comparative Examples 2 and 3, and generation of a trihalomethane .

&Quot; Changes in effective halogen concentration over time in water containing a trihalomethane precursor &quot;

Preparation of composition 2 '

Based on the description in JP-A-11-506139.

The pH of the composition 2 'was 14, the effective halogen concentration (effective chlorine conversion concentration) was 5 wt%, and the bromic acid concentration was 15 mg / kg.

(1) To a pure solution of 27.0 g of 40% by weight sodium bromide, 41.7 g of a 12% sodium hypochlorite solution was added and stirred.

(2) 56.0 g of pure water, 26.0 g of sulfamic acid and 18.0 g of sodium hydroxide was prepared.

(3) To the solution of (1), 31.3 g of the stabilizing solution of (2) was added with stirring to obtain the desired composition 2 '.

&Lt; Example 6, Comparative Example 4 >

The simulated seawater A having a trihalomethane generating capacity of 0.11 mg / L under the conditions shown in Table 5 (8.9 mg / L of humic acid (produced by Wako Pure Chemical Industries, Ltd.) as a precursor of a trihalomethane was added to artificial seawater, TOC: 5 mg / L), or simulated sea water B (trichloromethane having a trihalomethane generating capacity of 0.04 mg / L) (8.9 mg / L of humic acid (manufactured by Wako Pure Chemical Industries, Ltd.) as a trihalomethane precursor (TOC: 5 mg / l) or a simulated water C having a trihalomethane generating capacity of 0.01 mg / l (8.9 mg / l of pure water as a precursor of a trichloromethane precursor, produced by Wako Pure Chemical Industries, Ltd.) that the added, TOC: in each 5㎎ / ℓ), composition 1, composition 2 ", or the composition 4, as an active halogen 10㎎ / ℓ (as Cl ₂₎ or 5㎎ / ℓ (as Cl ₂₎ . The pH of the test solution was adjusted to be 8.4 using an aqueous sodium hydroxide solution or an aqueous sulfuric acid solution, and the solution was stored at room temperature (25 DEG C) under light-shielding conditions, and the change with time in the total halogen concentration was measured. The results are shown in Table 5. The simulated sea water A and the simulated sea water B were subjected to artificial seawater (Aquamarine (registered trademark) manufactured by Yashima Pure Chemicals Co., Ltd.) Was dissolved in pure water. The productivity of the trihalomethanes was measured in the same manner as in Example 1.

In addition, the total halogen concentration (effective chlorine conversion concentration) was measured according to the following procedure.

The effective halogen concentration was determined by diluting the sample and using a multi-item water quality analyzer DR / 4000 from HACH (for total halogen concentration, the measurement item is "total chlorine"), an effective chlorine measurement method (DPD (As mg / l (as Cl ₂ )) measured by the &lt; RTI ID = 0.0 &gt; The term "effective halogen" used herein is a value measured by an effective chlorine measurement method (DPD method). The effective bromine concentration (mg / l (as Cl ₂ )), which is the effective halogen concentration in terms of chlorine, can be calculated from the effective chlorine concentration and the measured value by the effective chlorine measurement method (DPD method) is 2.25 (159.8 The molecular weight of chlorine (Cl ₂ ) is 70.9 (g / mol) and the molecular weight of bromine (Br ₂ ) is 159.8 (g / mol) do).

Example
6-1 Example
6-2 Example
6-3 Example
6-4 Comparative Example
4-1 Comparative Example
4-2 Comparative Example
4-3 adding
drugs Composition 1 Composition 1 Composition 1 Composition 2 ' Composition 4 Composition 4 Composition 4 water Simulated sea water A Simulated sea water B Number of simulations C Simulated sea water A Simulated sea water A Simulated sea water B Number of simulations C gun
halogen
[Mg / l] gun
halogen
[Mg / l] gun
halogen
[Mg / l] gun
halogen
[Mg / l] gun
halogen
[Mg / l] gun
halogen
[Mg / l] gun
halogen
[Mg / l] On start 10.0 5.0 10.0 10.0 10.0 5.0 10.0 After 1 day 8.6 3.8 8.5 8.1 6.5 3.2 8.3 3 days later 8.2 3.4 8.3 7.3 3.2 2.0 7.2 After 7 days 7.5 3.1 7.7 6.7 0.8 0.4 6.6

ingredient Simulated sea water A Simulated sea water B The amount of each component [g] contained in 20 liters of simulated seawater Magnesium chloride hexahydrate 222.23 16.988 Calcium chloride dihydrate 30.70 2.347 Strontium hexahydrate 0.85 0.065 Potassium chloride 13.89 1.062 Sodium hydrogencarbonate 4.02 0.307 Potassium bromide 2.01 0.154 Boric acid 0.54 0.041 Sodium fluoride 0.06 0.005 Sodium chloride 490.68 37.509 Sodium sulfate (anhydrous) 81.88 6.259 Humic acid 0.18 0.18 pure Residue Residue Bromide ion concentration [mg / l] 67.5 5.2

In Table 5, from the comparison between the examples and the comparative examples, it was found that the compositions 1 and 2 'remained high in the residual halogen over a long period of time as compared with the composition 4, and that the membrane could be effectively sterilized . Here, from the comparison between the comparative examples 4-1 and 4-2 and the comparative example 4-3, the reason why the rate of decrease in the total halogen concentration in the simulated seawater A and B is larger than the simulated number C is as follows. It is considered that bromide ions in seawater reacted and changed to more unstable babochromic acid. Further, in Examples 6-1, 6-2 and 6-4, the compositions 1 and 2 'as the hypobromic acid stabilizing composition were suppressed from lowering the total halogen concentration even in the simulated seawater as compared with the composition 4. The reason for this is that the hypobromic acid stabilizing composition is more stable than hypochlorous acid or hypobromic acid, and a part of the hypobromic acid stabilizing composition reacts with chloride ions in artificial seawater, resulting in highly stable binding chlorine It is considered.

&Quot; Rejection rate of reverse osmosis membrane (RO membrane) after immersion in a sterilizing agent solution and its influence on permeation amount &quot;

&Lt; Example 7 >

Table 7 shows the results of measuring the conductivity rejection rate and permeation rate of the membranes after the membranes were immersed in each bactericide solution for 30 days.

(Exam conditions)

Membrane: polyamide-based reverse osmosis membrane ES15 manufactured by Nitto Denka Co., Ltd.

· Number of tests: Simulated sea water A or simulated sea water B or simulated water C

Agent: added so as to give a total halogen concentration of 10 mg / L (as Cl ₂ )

Test water pH: Adjusted to a predetermined pH using an aqueous sodium hydroxide solution or an aqueous sulfuric acid solution

· Membrane immersion period: 30 days

Conditions for immersion: Under light-shielding conditions, room temperature (25 ° C)

(Method of measuring rejection rate)

· Tester: Flat Tester

Operating pressure: 0.75MPa

· Raw water: Sagamihara well (pH 7.2, conductivity: 24 mS / m)

Conductivity rejection rate [%] = 100 - [permeated water conductivity / water conductivity rate] × 100

Percentage of permeated water retained [%] = [Permeate amount of separator kept immersed in test water / Percentage of new separator permeated] × 100

Example
7-1 Example
7-2 Example
7-3 Example
7-4 Example
7-5 Example
7-6 Example
7-7 Comparative Example
5-1 Comparative Example
5-2 adding
drugs Composition 1 Composition 1 Composition 1 Composition 1 Composition 1 Composition 1 Composition 2 ' Composition 4 Composition 4 Number of Tests imitation
Sea water A Mock number
C imitation
Sea water B imitation
Sea water B imitation
Sea water B imitation
Sea water B Number of simulations C imitation
Sea water A Mock number
C Test water pH 8.4 8.4 8.4 6.0 5.5 5.0 8.4 8.4 8.4 RO membrane
Conductivity
Exclusion rate (%)
98
98
98
98
98
98
98
<70
<70 RO membrane
Water addition amount retention ratio (%)
> 90
> 90
> 90
> 90
79
60
> 90
> 90
> 90

In the composition 4, when the separation membrane was kept immersed for a long period of time, the separation membrane deteriorated and the rate of blocking greatly deteriorated. However, the compositions 1 and 2 'retained a high blocking rate even when the separation membrane was kept immersed for a long period of time.

As described above, in the embodiment using the hypobromous acid stabilizing composition, it was found that in the membrane separation system in which the operation and the operation stop are performed, deterioration of the separation membrane can be suppressed and the separation membrane can be effectively sterilized during operation stoppage.

1: membrane separation system 10: raw water tank
12: membrane separator 14: pump
16: raw water pipe 18: raw water supply pipe
20: permeate water pipe 22: concentrated water pipe
24: Disinfectant supply piping

Claims (13)

Characterized in that a reaction product of a bromine-based oxidizing agent or a bromine compound and a chlorinated oxidizing agent is present in the feed water or washing water to a membrane separation apparatus containing a separation membrane containing a trihalomethane precursor, slime) suppression method. Characterized in that a bromine-based oxidizing agent or a reaction product of a bromine compound and a chlorine-based oxidizing agent and a sulfamic acid compound are present in water or washing water in a membrane separation apparatus containing a separation membrane containing a trihalomethane precursor, Of the slurry. A reaction product of a bromine-based oxidizing agent or a reaction product of a bromine compound and a chlorine-based oxidizing agent and a reaction product of a sulfamic acid compound in water or washing water in a membrane separation apparatus containing a separation membrane containing a trihalomethane precursor &Lt; / RTI &gt; Characterized in that a reaction product of bromine and a sulfamic acid compound or a reaction product of bromine and a sulfamic acid compound is present in water or washing water in a membrane separation apparatus containing a separation membrane containing a trihalomethane precursor Of the slurry. 5. The process according to claim 4, wherein the reaction product of bromine and sulfamic acid compound is obtained by a process comprising the step of adding bromine to a mixed solution containing water, an alkali and a sulfamic acid compound under an inert gas atmosphere Characterized in that the slime suppression method of the separator. The separation membrane according to any one of claims 1 to 5, characterized in that the concentration of the trihalomethane precursor in the water supply or washing water is 0.001 mg / Inhibition method. The slime suppressing method according to any one of claims 1 to 6, wherein the separation membrane is a polyamide-based polymer membrane. 8. A method according to any one of claims 1 to 7, wherein the trihalomethane precursor comprises humin. 9. The method according to any one of claims 1 to 8, wherein the water or washing water further contains bromide ions. The slime suppressing method according to claim 9, wherein the concentration of bromide ions in the feed water or washing water is 5 mg / L or more. 11. The membrane separation apparatus according to any one of claims 1 to 10, wherein the membrane separation apparatus including the separation membrane is operated and stopped, wherein during the operation stop of the membrane separation apparatus, the bromine-based oxidizing agent, Or a reaction product of a bromine compound and a chlorine-based oxidizing agent, or a reaction product of the bromine-based oxidizing agent or a bromine compound and a chlorine-based oxidizing agent, or a sulfamic acid compound, or a bromine-based oxidizing agent or a bromine- Wherein the reaction product of the bromine and the sulfamic acid compound is present or the reaction product of the bromine and the sulfamic acid compound is present. The slime suppressing method according to claim 11, wherein the pH of the water present in the membrane separation apparatus is at least pH 5.5. The slime suppressing method according to claim 10 or 11, wherein the water present in the membrane separation apparatus is at least one of seawater and brine.

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