KR20190057369A - A water treatment method and a water treatment apparatus using a reverse osmosis membrane - Google Patents

Abstract

There is provided a water treatment method for treating ammonia-containing water to be treated with a reverse osmosis membrane, the method comprising the step of inhibiting permeation of a reverse osmosis membrane of a bactericide containing a chlorine-based oxidizing agent or a bromine-based oxidizing agent and a sulfamic acid compound. A water treatment method using a reverse osmosis membrane for treating ammonia-containing water to be treated with a reverse osmosis membrane, comprising the steps of: introducing a bromine-based oxidizing agent or a bactericide containing a chlorine-based oxidizing agent and a sulfamic acid compound into a water- Membrane or a cationic sub-membrane, using a reverse osmosis membrane.

Description

A water treatment method and a water treatment apparatus using a reverse osmosis membrane

The present invention relates to a water treatment method and a water treatment apparatus using a reverse osmosis membrane (RO membrane).

In the water treatment method using a reverse osmosis membrane (RO membrane), various sanitizers (slime inhibitors) are generally used as measures against biofouling. Chlorine-based oxidizing agents such as hypochlorous acid are typical bactericides and are usually added to the shear of the reverse osmosis membrane for sterilization purposes in the system. Since the chlorine-based oxidizing agent is highly likely to deteriorate the reverse osmosis membrane, it is generally operated by reducing the chlorine-based oxidizing agent immediately before the reverse osmosis membrane or intermittently introducing the chlorine-based oxidizing agent into the reverse osmosis membrane.

In addition, a method of allowing a binding chlorine agent composed of a chlorine-based oxidizing agent and a sulfamic acid compound as a bactericide (slime inhibitor) in water to be treated in a reverse osmosis membrane (see Patent Document 1), a method of reacting a bromine- And a method of adding a mixture or reaction product of a sulfamic acid compound to the water to be treated (see Patent Document 2).

A chloric oxidizing agent or a bactericide containing a bromine-based oxidizing agent and a sulfamic acid compound has a high sterilizing ability and is difficult to oxidize the polyamide-based reverse osmosis membrane and has a high rejection rate in the reverse osmosis membrane, It is effective because it has little influence on quality.

JP 2006-263510 A JP 2015-062889 A

However, when the water to be treated contains ammonia (ammonium ion), it was found that a part of the bactericide containing the chlorine-based oxidizing agent or the bromine-based oxidizing agent and the sulfamic acid compound permeates the reverse osmosis membrane. When the sterilizing agent permeates the reverse osmosis membrane, the deterioration of the treated water quality and the deterioration of the downstream equipment are caused, and it is desired to suppress the permeation.

An object of the present invention is to provide a method and an apparatus for suppressing the permeation of a reverse osmosis membrane of a bactericide containing a chlorine-based oxidizing agent or a bromine-based oxidizing agent and a sulfamic acid compound in a water treatment for treating a treated water containing ammonia with a reverse osmosis membrane .

The present invention relates to a water treatment method using a reverse osmosis membrane that treats for-treatment water containing ammonia with a reverse osmosis membrane, wherein a bromine-based oxidizing agent or a bactericide containing a chlorine-based oxidizing agent and a sulfamic acid compound is present in the for- , And the reverse osmosis membrane is a neutral membrane or a cation-immobilized membrane.

The present invention also provides a water treatment method using a reverse osmosis membrane that treats for-treatment water containing ammonia with a reverse osmosis membrane, wherein a disinfectant containing bromine and a sulfamic acid compound is present in the for- This is a water treatment method using a reverse osmosis membrane in which the reverse osmosis membrane is a neutral membrane or a cation-immobilized membrane.

In the water treatment method using the reverse osmosis membrane, it is preferable that the ammonium ion concentration in the for-treatment water is 1 mg / liter or more.

In the water treatment method using the reverse osmosis membrane, it is preferable that the ammonia in the for-treatment water containing ammonia is reduced, and the sterilizing agent is present in the ammonia-reduced water with reduced ammonia.

In the water treatment method using the reverse osmosis membrane, it is preferable that the ammonia concentration of the ammonia reduced water is 5 mg / liter or less.

In the water treatment method using the reverse osmosis membrane, it is preferable to reduce ammonia in the for-treatment water containing ammonia by ammonia stripping treatment.

In the water treatment method using the reverse osmosis membrane, ammonia in the for-treatment water containing ammonia is preferably reduced by ammonia decomposition treatment with an oxidizing agent.

The present invention also provides a water treatment apparatus using a reverse osmosis membrane for treating ammonia-containing water to be treated with a reverse osmosis membrane, wherein a disinfectant containing a bromine-based oxidizing agent or a chlorine-based oxidizing agent and a sulfamic acid compound And the reverse osmosis membrane is a neutral membrane or a cation-immobilized membrane.

The present invention also provides a water treatment apparatus using a reverse osmosis membrane that treats for-treatment water containing ammonia with a reverse osmosis membrane, wherein a disinfectant containing bromine and a sulfamic acid compound is present in the for- And a reverse osmosis membrane in which the reverse osmosis membrane is a neutral membrane or a cation-immobilized membrane.

In the water treatment apparatus using the reverse osmosis membrane, it is preferable that the ammonium ion concentration in the for-treatment water is 1 mg / liter or more.

The water treatment apparatus using the reverse osmosis membrane may further comprise an ammonia reducing means for reducing the ammonia in the for-treatment water containing ammonia, wherein the sterilizing agent is present in the ammonia reducing water in which the ammonia is reduced by the ammonia reducing means desirable.

In the water treatment apparatus using the reverse osmosis membrane, it is preferable that the ammonia concentration of the ammonia reduced water is 5 mg / liter or less.

In the water treatment apparatus using the reverse osmosis membrane, it is preferable to provide an ammonia stripping treatment apparatus as the ammonia reduction means.

In the water treatment apparatus using the reverse osmosis membrane, it is preferable that the ammonia decomposing means by an oxidizing agent is provided as the ammonia reducing means.

In the present invention, permeation of a reverse osmosis membrane of a bactericide containing a chlorine-based oxidizing agent or a bromine-based oxidizing agent and a sulfamic acid compound can be suppressed in a water treatment method and a water treatment apparatus for treating ammonia-containing water to be treated with a reverse osmosis membrane .

BRIEF DESCRIPTION OF DRAWINGS FIG. 1 is a schematic block diagram showing an example of a water treatment system to which a water treatment method using a reverse osmosis membrane according to an embodiment of the present invention is applied.
2 is a schematic configuration diagram of a flat membrane test apparatus used for evaluation of a blocking ratio in a reverse osmosis membrane in Examples and Comparative Examples.
3 is a graph showing the bactericidal permeability (%) to the surface zeta potential (-㎷) in Example 1 and Comparative Example 1. Fig.
4 is a graph showing the bactericidal permeability (%) to the ammonium ion concentration (mg / l) in Example 2 and Comparative Example 2. Fig.
5 is a graph showing the bactericidal permeability (%) to the ammonium ion concentration (mg / l) in Example 3 and Comparative Example 3. Fig.
6 is a schematic structural view showing an example of a water treatment apparatus using a reverse osmosis membrane according to an embodiment of the present invention.
7 is a schematic block diagram showing an example of a water treatment system to which a water treatment apparatus using a reverse osmosis membrane according to an embodiment of the present invention is applied.
8 is a graph showing the bactericidal permeability (%) to the ammonium ion concentration (mg / l) in Example 4-1.
9 is a graph showing the fungicide permeability (%) to the ammonium ion concentration (mg / l) in Example 4-2.
10 is a schematic configuration diagram of a pilot apparatus used for evaluating the permeability of the bactericide in Examples 5 to 8;

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.

<Water treatment method using reverse osmosis membrane>

A water treatment method using a reverse osmosis membrane according to an embodiment of the present invention is characterized in that a bromine-based oxidizing agent or a bactericide containing a chlorine-based oxidizing agent and a sulfamic acid compound is present in the water to be treated containing ammonia and a neutral membrane or a cation This is a method using a charge film. &Quot; A bactericide comprising a bromine-based oxidizing agent and a sulfamic acid compound " may be a sterilizing agent containing a stabilized hypobromous acid composition comprising a mixture of " bromine-based oxidizing agent " and "Quot; reaction product of the compound " of the present invention. A " bactericide containing a chlorine-based oxidizing agent and a sulfamic acid compound " may be a bactericide containing a stabilized hypochlorous acid composition comprising a mixture of " chlorine-based oxidizing agent " and " &Lt; / RTI &gt; may be a sterilizing agent containing a stabilized hypochlorous acid composition.

That is, a water treatment method using a reverse osmosis membrane according to an embodiment of the present invention is a method of treating a for-treatment water containing ammonia with a reverse osmosis membrane, wherein a "bromine-based oxidizer" , Or a mixture of a " chlorine-based oxidizing agent " and a " sulfamic acid compound " is used, and a neutral membrane or a cationic charged membrane is used as a reverse osmosis membrane. Thus, it is considered that a stabilized hypobromous acid composition or a stabilized hypochlorous acid composition is produced in the water to be treated.

Further, a water treatment method using a reverse osmosis membrane according to an embodiment of the present invention is a method of treating a for-treatment water containing ammonia with a reverse osmosis membrane, wherein a reaction product of a bromine-based oxidizing agent and a sulfamic acid compound Quot; or a stabilized hypochlorous acid composition which is a " reaction product of a chlorine-based oxidizing agent and a sulfamic acid compound ", and using a neutral membrane or a cationic charged membrane as a reverse osmosis membrane.

More specifically, the water treatment method using the reverse osmosis membrane according to the embodiment of the present invention is a method of treating the for-treatment water containing ammonia with a reverse osmosis membrane, in which "bromine", "bromine chloride" , &Quot; hypobromic acid " or " a reaction product of sodium bromide and hypochlorous acid " and a " sulfamic acid compound " are used as a reverse osmosis membrane and a neutral membrane or a cationic charged membrane is used as a reverse osmosis membrane. Alternatively, a mixture of "hypochlorous acid" and "sulfamic acid compound" is present in the water to be treated, and a neutral membrane or a cationic charged membrane is used as a reverse osmosis membrane.

Further, the water treatment method using the reverse osmosis membrane according to the embodiment of the present invention is a method for treating the for-treatment water containing ammonia with a reverse osmosis membrane, wherein, for example, "bromine and sulfamic acid compounds Reaction product of sodium bromide and hypochlorous acid and reaction product of sulfamic acid compound ", " reaction product of sodium bromide and hypochlorous acid ", " reaction product of sodium bromide and hypochlorous acid compound & In the presence of a stabilized hypobromous acid composition and using a neutral membrane or a cationic charged membrane as the reverse osmosis membrane. Alternatively, a stabilized hypochlorous acid composition which is a "reaction product of hypochlorous acid and a sulfamic acid compound" is present in the water to be treated, and a neutral membrane or a cationic charged membrane is used as a reverse osmosis membrane.

The present inventors have repeatedly found that when the water to be treated contains ammonia, the permeability of the bactericide is changed by the charge of the reverse osmosis membrane to be used. The reverse osmosis membrane was usually before the load, but the permeability of the germicide decreased as the membrane approached the neutral charge. Permeation of a reverse osmosis membrane of a bactericide is suppressed by using a neutral membrane or a cationic charge membrane as a reverse osmosis membrane when a bromine-based oxidizing agent or a bactericide containing a chlorine-based oxidizing agent and a sulfamic acid compound is present in water to be treated containing ammonia .

In the water treatment method using the reverse osmosis membrane according to the present embodiment, the stabilized hypobromous acid composition or the stabilized hypochlorous acid composition exhibits a slime suppressing effect equal to or higher than that of hypochlorous acid oxidizing agent such as hypochlorous acid, It is possible to suppress oxidation deterioration of the reverse osmosis membrane while suppressing fouling in the reverse osmosis membrane because the influence of deterioration on the permeation membrane is low. Therefore, the stabilized hypobromous acid composition or the stabilized hypochlorous acid composition used in the water treatment method using the reverse osmosis membrane according to the present embodiment is a slime inhibitor used in the water treatment method for treating the for-treatment water containing ammonia with a reverse osmosis membrane .

Among the water treatment methods using the reverse osmosis membrane according to the present embodiment, in the case of the " bactericide containing a bromine-based oxidizing agent and a sulfamic acid compound ", there is no chlorine-based oxidizing agent and the influence of deterioration on the reverse osmosis membrane is lower. When a chlorine-based oxidizing agent is contained, generation of chloric acid is a concern.

Among the water treatment methods using the reverse osmosis membrane according to the present embodiment, when the "bromine-based oxidizing agent" is bromine, the influence of deterioration on the reverse osmosis membrane is remarkably low because no chlorine-based oxidizing agent is present.

In the water treatment method using the reverse osmosis membrane according to the present embodiment, for example, even when "bromine-based oxidizing agent" or "chlorine-based oxidizing agent" and "sulfamic acid compound" are injected into the water to be treated containing ammonia by a drug injection pump or the like do. The "bromine-based oxidizing agent" or the "chlorine-based oxidizing agent" and the "sulfamic acid compound" may be separately added to the for-treatment water, or may be added to the for-treatment water after mixing the undiluted solutions.

Further, for example, the reaction product of the bromine-based oxidizing agent and the sulfamic acid compound or the reaction product of the chlorine-based oxidizing agent and the sulfamic acid compound may be injected into the water to be treated containing ammonia by a drug injection pump or the like.

In the water treatment method using the reverse osmosis membrane according to the present embodiment, the equivalent ratio of the "sulfamic acid compound" to the equivalent of "bromine-based oxidizer" or "chlorine-based oxidizer" is preferably 1 or more, Is more preferable.

If the ratio of the equivalents of the "sulfamic acid compound" to the equivalents of the "bromine-based oxidizing agent" or "chlorinated oxidizing agent" is less than 1, there is a possibility of deteriorating the film, and if it exceeds 2, the production cost may be increased.

The total chlorine concentration in contact with the reverse osmosis membrane is preferably 0.01 to 100 mg / l 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 reverse osmosis membrane and corrosion such as piping may occur.

In the water treatment method using the reverse osmosis membrane according to the present embodiment, the ammonium ion concentration in the for-treatment water is preferably 1 mg / L or more, more preferably 5 mg / L or more. When the ammonium ion concentration in the for-treatment water is 1 mg / liter or more, the change in the permeability of the bactericide due to sub-culture is large, and when the ammonium ion concentration in the water to be treated is 5 mg / liter or more, It grows.

(Ammonia concentration (mg / l) / bactericide concentration (total chlorine concentration: mg / l)) of the concentration of ammonia to the total chlorine concentration in the for-treatment water is, for example, in the range of 0.01 to 50, 1.0. &Lt; / RTI &gt; When the ratio of the concentration of ammonia to the total chlorine concentration in the water to be treated is less than 0.01 or more than 1.0, the difference in the permeability of the bactericide between the anion sub-membrane and the neutral membrane and the cationic sub-membrane may be small.

Examples of the bromine-based oxidizing agent include bromine (liquid bromine), bromine chloride, bromine acid, bromate, and hypobromous acid. The hypobromic acid may be produced by reacting a brominated compound such as sodium bromide with a chlorinated oxidizing agent such as hypochlorous acid.

Among them, the preparation of "the reaction product of bromine and sulfamic acid compound (mixture of bromine and sulfamic acid compound)" or "bromine and sulfamic acid compound" using bromine is "a mixture of hypochlorous acid and bromine compound Fumaric acid " and a preparation of " bromine chloride and sulfamic acid ", it is more preferable as a slime inhibitor for a reverse osmosis membrane because the byproduct life of bromic acid is small and the reverse osmosis membrane is not further deteriorated.

That is, a water treatment method using a reverse osmosis membrane according to an embodiment of the present invention is a method in which bromine and a sulfamic acid compound are present (a mixture of a bromine and a sulfamic acid compound is present) in water to be treated containing ammonia desirable. Further, it is preferable that a reaction product of bromine and a sulfamic acid compound is present in the water to be treated.

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

The chlorine-based oxidizing agent includes, for example, 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, alkali hypochlorite such as calcium hypochlorite and barium hypochlorite, sodium chlorite such as sodium chlorite and potassium chlorite, Alkaline earth metal salts such as alkali metal salts and barium chlorites, other metal chlorites such as nickel chlorite, alkali metal chlorides such as ammonium chlorate, sodium chlorate and potassium chlorate, alkaline earth metal chlorides such as calcium chlorate and barium chlorate, etc. . These chlorine-based oxidizing agents may be used singly or in combination of two or more kinds. As the chlorine-based oxidizing agent, sodium hypochlorite is preferably used from the viewpoint 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 sulfamoic acid compound, for example, there may be mentioned sulfamic acid (amide sulfuric acid) in which two R groups are hydrogen atoms, and N-methylsulfamic acid, N- ethylsulfamic acid, N-propylsulfamic acid, N- Sulfamic acid, N, N-dimethylsulfamic acid, N, N-diethylethylsulfamic acid, N, N-dimethylsulfamic acid, and N, N-dimethylsulfamic acid, wherein one of the two R groups is a hydrogen atom and the other is an alkyl group having 1 to 8 carbon atoms. Two R groups such as fumaric 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 and an N-phenyl sulfamic acid group is a hydrogen atom and the other is an aryl group having 6 to 10 carbon atoms, or a salt thereof, and the like can be given . Examples of sulfamates include 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 view of environmental load and the like.

In the water treatment method using the reverse osmosis membrane according to the present embodiment, an 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. The alkali may be used not as a solid but as an aqueous solution.

The water treatment method using the reverse osmosis membrane according to the present embodiment can be suitably applied to a polyamide-based high molecular membrane as a reverse osmosis membrane in recent years. 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 water treatment method using the reverse osmosis membrane according to the present embodiment, such a remarkable deterioration of the membrane performance hardly occurs even in the polyamide-based polymer membrane.

The reverse osmosis membrane includes a neutral membrane, an anion sub-membrane and a cationic charge membrane. In the present specification, a film having a zeta potential at a pH of 7.0 to less than 5 kPa, a zeta potential film having a zeta potential of not less than 5 kPa, and a film having a zeta potential of not less than 5 kPa, Is defined as the anion-exchange membrane. The zeta potential of the neutral film is preferably -5 ㎷ or more, more preferably -3.9 ㎷ or more, even more preferably -1.3 ㎷ or more. The upper limit of the zeta potential of the cationic charge film is not particularly limited, but is, for example, 20 kPa or less.

In the water treatment method using the reverse osmosis membrane according to the present embodiment, by using the neutral membrane or the cationic charge membrane as the reverse osmosis membrane, it is possible to obtain a sterilizing agent containing chlorine-based oxidizing agent or bromine-based oxidizing agent and sulfamic acid compound Permeation of the permeable membrane can be suppressed.

Examples of commercially available neutral membranes include BW30XFR (manufactured by Dow chemical), LFC3 (manufactured by Nitto Denko Corporation), TML20 (manufactured by Toray Industries, Inc.), OFR625 (manufactured by Organo Corporation) And the like.

As a commercially available cationic lower electrophoresis film, for example, ES10C (manufactured by Nitto Denko Corporation) and the like can be given.

Examples of commercially available negative ion charge-controlling membranes include ES15, ES20, CPA3 and CPA5 (manufactured by Nitto Denko Corporation) and RE-8040BLN (manufactured by Unzin Corporation).

In the water treatment method using the reverse osmosis membrane according to the present embodiment, the pH of the for-treatment water supplied to the reverse osmosis membrane treatment apparatus having a reverse osmosis membrane is preferably 5.5 or more, more preferably 6.0 or more, desirable. If the pH of the water to be treated is less than 5.5, the permeation water may be lowered. The upper limit of the pH of the water to be treated is not particularly limited as long as it is not higher than the upper limit pH of application (for example, pH 10) of a normal reverse osmosis membrane. However, considering scale precipitation of hardness components such as calcium, It is preferable that the pH is, for example, 9.0 or less. When the water treatment method using the reverse osmosis membrane according to the present embodiment is used, deterioration of the reverse osmosis membrane and deterioration of water quality of the treated water (permeated water) are suppressed by operating the pH of the for-treatment water at the pH of 5.5 or more, It is possible to secure a sufficient amount of permeated water while exercising.

In the reverse osmosis membrane treating apparatus, when a scale occurs at pH 5.5 or higher of the water to be treated, a dispersant may be used in combination with the above-mentioned bactericide in order to suppress the scale. Examples of the dispersing agent include polyacrylic acid, polymaleic acid, and phosphonic acid. The amount of the dispersant to be added to the water to be treated 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 dispersing agent, for example, it is preferable that the silica concentration in the RO concentrated water is below the solubility, and the LANGELIER index, which is an index of the calcium scale, And adjusting the operating conditions such as the recovery rate of the film processing apparatus.

Examples of applications of the reverse osmosis membrane treating apparatus include pure water production, seawater desalination, drainage recovery, and the like.

The water treatment method using the reverse osmosis membrane according to the present embodiment is particularly applied to the application of drainage water, for example, to the recovery of the electronic industrial wastewater. The electronic industrial wastewater often contains a low-molecular organic matter and is a flow that drains and collects water. For example, the biological industrial wastewater includes a biological treatment system 10 having a biological treatment apparatus 10 and a membrane treatment apparatus 14 There is considered a process including a reverse osmosis membrane treatment system 26 including a reverse osmosis membrane treatment device 22 as a water treatment device applied to a water treatment method using a reverse osmosis membrane according to the present embodiment .

The water treatment system 1 shown in Fig. 1 includes a biological treatment device 10, a biological treatment water tank 12, a membrane treatment device 14 as a membrane treatment means, a membrane treatment water tank 18, And a reverse osmosis membrane treatment system 26 as a water treatment apparatus using a reverse osmosis membrane. The reverse osmosis membrane treatment system 26 includes a reverse osmosis membrane treatment device 22 having a neutral membrane or a cationic charge membrane as the reverse osmosis membrane treatment means. The reverse osmosis membrane treatment system 26 may include a water treatment tank 20 for storing the water to be treated and a second reverse osmosis membrane treatment device 24 as a second reverse osmosis membrane treatment means.

In the water treatment system 1, for example, the electronic industrial wastewater is sent to the biological treatment apparatus 10 as raw water, and biological treatment is performed in the biological treatment apparatus 10 (biological treatment step). The biologically treated biologically treated water is stored in the biological treatment water tank 12 as required and then sent to the membrane treatment device 14 where the membrane treatment is carried out by the treatment tank 14 (Membrane treatment process). The film-treated membrane treatment water is stored in the membrane treatment tank 18 as necessary, and then sent to the water treatment tank 20 of the reverse osmosis membrane treatment system 26 as the water to be treated and stored. The water to be treated is sent to the reverse osmosis membrane treatment device 22 from the water treatment tank 20 and the reverse osmosis membrane treatment is performed by the neutral membrane or the cationic charge membrane in the reverse osmosis membrane treatment device 22 Reverse osmosis membrane treatment process). The permeated water obtained by the reverse osmosis membrane treatment is discharged outside the system. The concentrated water may be discharged to the outside of the system, fed to the second reverse osmosis membrane treating device 24 as required, and further subjected to the reverse osmosis membrane treatment in the second reverse osmosis membrane treating device 24 Reverse osmosis membrane treatment process). The concentrated water obtained by the second reverse osmosis membrane treatment is discharged outside the system. The permeated water may be discharged out of the system, fed to the treated water tank 20 if necessary, and circulated.

A sterilizing agent containing a bromine-based oxidizing agent or a chlorine-based oxidizing agent and a sulfamic acid compound is present in the water to be treated, but the sterilizing agent may be at least one of the biological treatment water tank 12, the membrane treatment water tank 18, One species may be added. The sanitizer includes a pipe connecting the biological treatment device 10 and the biological treatment water tank 12, a pipe connecting the biological treatment water tank 12 and the membrane treatment device 14, a membrane treatment device 14, The pipe for connecting the membrane treatment water tank 18 and the water treatment tank 20 or the pipe for connecting the water treatment tank 20 and the reverse osmosis membrane treatment device 22 do. The most advantageous in terms of cost and the like is that the addition to the water treatment tank 20 or the addition to the pipe connecting the membrane treatment tank 18 and the water treatment tank 20 or the addition of the water treatment tank 20 and the reverse osmosis membrane And the addition to the piping connecting the processing device 22. [ However, if the occurrence of slime is confirmed at the time of the membrane treatment tank 18 before being concentrated by the reverse osmosis membrane of the reverse osmosis membrane treatment apparatus 22, the sterilization treatment may be performed in the membrane treatment water tank 18, However, since the membrane treatment water in the membrane treatment tank 18 is often used for backwashing the membrane treatment apparatus 14, a part of the added amount of the sterilizing agent is liable to be wasted. When a bactericide is added to the biological treatment water tank 12 or the piping before or after the biological treatment tank 12, the bactericidal component is consumed by the suspended organic matter after the biological treatment, thereby increasing the amount of the bactericide added and increasing the operation cost. It is better to employ when the risk of occurrence is recognized.

The water treatment system 1 of FIG. 1 exemplifies the biological treatment system 16 having the biological treatment apparatus 10, the biological treatment water tank 12 and the membrane treatment apparatus 14 separately, A combined membrane separation activated sludge device (MBR) may be used.

In the water treatment system 1 of Fig. 1, a low molecular organic material or the like contained in raw water is decomposed by a biological treatment, a biomass and the like are blocked by a membrane treatment device 14 having a detachable membrane, Or the reverse osmosis membrane treatment device 22 having a cationic charged membrane, the various ions and remaining organic substances are blocked to obtain treated water (permeated water). In such drainage, the drainage water itself contains ammonia, or ammonia is often generated by biological treatment. For example, biological treatment of waste water containing tetramethylammonium hydroxide as an organic matter tends to generate ammonia.

At this time, the biofouling of the downstream tank membrane or the reverse osmosis membrane is a concern due to the biological metabolites generated by the biological treatment or the low molecular organic matter remaining after the biological treatment. Although hypochlorous acid having a high sterilizing power may be used, hypochlorous acid may deteriorate the polyamide-based reverse osmosis membrane, which has become mainstream in recent years. It is also considered to form a chemical injection point of the activated carbon tower or the reducing agent on the front end of the reverse osmosis membrane, but all of the initial operation costs are problematic. Thus, in the water treatment system 1, by the presence of a bromine-based oxidizing agent or a bactericide containing a chlorine-based oxidizing agent and a sulfamic acid compound in the water to be treated containing ammonia, the sterilizing ability is high and the polyamide- It is difficult to deteriorate, the rejection rate in the reverse osmosis membrane is high, and the effect on the treated water (permeated water) quality in the rear stage is small.

In the case where the bactericide is added as described above, when the bactericide permeates the treated water side, deterioration of the treated water quality becomes a problem. Therefore, in the water treatment method using the reverse osmosis membrane according to the present embodiment, the use of the neutral membrane or the cationic charge membrane as the reverse osmosis membrane in the reverse osmosis membrane treatment device 22 makes it possible to detect the sterilizing agent in the permeated water almost Permeation of the reverse osmosis membrane of the bactericide is suppressed.

At this time, it is preferable that the pH of the water to be treated supplied to the reverse osmosis membrane treatment device 22, that is, the operation pH of the reverse osmosis membrane treatment device 22 is 9 or less. On the alkali side, which exceeds pH 9, the desalination rate of the reverse osmosis membrane may decrease and the oxidizing power of the bactericide may decrease. When the pH of the water to be treated supplied to the reverse osmosis membrane treatment device 22 is 9 or less, the water quality of the RO permeated water is maintained more favorably, and slime generation is further suppressed.

In the flow of drainage as in the water treatment system 1, a second reverse osmosis membrane treatment device 24 (brine RO) is generally installed in order to increase the water recovery rate. The second reverse osmosis membrane treating device 24 uses the concentrated water of the reverse osmosis membrane treating device 22 as raw water to return the permeated water to the water treatment tank 20 and discharge the concentrated water out of the system. If the permeability of the sterilizing agent is low in the reverse osmosis membrane treating device 22, the second reverse osmosis membrane treating device 24 is also liable to generate slime, and if the sterilizing agent component remains in the raw water of the second reverse osmosis membrane treating device 24 . By using a neutral membrane or a cationic charged membrane as the reverse osmosis membrane in the reverse osmosis membrane treatment device 22, a large amount of the bactericide component remains in the raw water of the second reverse osmosis membrane treatment device 24 and the second reverse osmosis membrane treatment The occurrence of slime in the device 24 is suppressed.

In the water treatment system 1 of Fig. 1, biological treatment is described as an example of pretreatment of reverse osmosis membrane treatment. However, in the pretreatment step of reverse osmosis membrane treatment, biological treatment, coagulation treatment, coagulation sedimentation treatment, A combination of two or more of biological, physical or chemical pretreatment such as treatment, membrane separation treatment, activated carbon treatment, ozone treatment, ultraviolet irradiation treatment, and the like may be carried out as necessary.

In the reverse osmosis membrane treatment system 26, a pump, a safety filter, a flow rate measuring device, a pressure measuring device, a temperature measuring device, an oxidation-reduction potential (ORP) measuring device, a residual chlorine measuring device, A conductivity measuring device, a pH measuring device, an energy recovery device, and the like may be provided as required.

In the water treatment system 1, scale inhibitors other than the stabilized hypobromous acid composition or the stabilized hypochlorous acid composition, a pH adjuster, a biological treatment water tank 12, pipings before and after the piping, a membrane treatment water tank 18, Treated water, at least one of the piping before and after the piping, the treated water tank 20, and the piping before and after the pipeline, the treated water, the treated water and the treated water.

An outline of an example of a water treatment apparatus using a reverse osmosis membrane according to an embodiment of the present invention is shown in Fig. 6, and the structure thereof will be described.

The water treatment apparatus 3 shown in Fig. 6 is an ammonia reduction means for reducing ammonia in the for-treatment water containing ammonia. The ammonia reduction apparatus 30 and the reverse osmosis membrane treatment means have a neutral membrane or a cationic charge membrane And a reverse osmosis membrane treating device (34). The water treatment apparatus 3 may be provided with an ammonia reduction water tank 32 for storing ammonia reduction water.

In the water treatment apparatus 3, an untreated water pipe 36 is connected to the entrance of the ammonia reduction device 30. [ The outlet of the ammonia reduction device 30 and the inlet of the ammonia reduction water tank 32 are connected by an ammonia reduction water pipe 38. The outlet of the ammonia reducing water tank 32 and the inlet of the reverse osmosis membrane treating device 34 are connected by a sterilizing agent-containing water pipe 40. Permeate pipe 42 is connected to the permeate outlet of the reverse osmosis membrane treatment device 34 and a concentrated water pipe 44 is connected to the concentrated water outlet. A sterilizing agent addition pipe 46 is connected to the ammonia reduction water tank 32.

The operation of the water treatment method and the water treatment apparatus 3 according to the present embodiment will be described.

In the water treatment apparatus 3, the water to be treated containing ammonia (ammonium ion) is supplied to the ammonia reduction apparatus 30 through the water supply pipe 36, and in the ammonia reduction apparatus 30, (Ammonia reduction process).

Ammonia reduction water whose ammonia has been reduced by the ammonia reduction apparatus 30 is sent to the ammonia reduction water tank 32 through the ammonia reduction water pipe 38 as necessary and stored. In the ammonia reducing water tank 32, a bromine-based oxidizing agent or a bactericidal agent containing a chlorine-based oxidizing agent and a sulfamic acid compound is added to the ammonia-reduced water to provide a sterilizing agent (a bactericide addition step). The bactericide may be added to the ammonia-reducing water pipe 38 or may be added to the bactericide-containing water pipe 40.

The sterilizing agent-containing water containing the sterilizing agent is supplied to the reverse osmosis membrane treating device 34 through the sterilizing agent-containing water pipe 40 and the reverse osmosis membrane treating device 34 performs reverse osmosis membrane treatment Reverse osmosis membrane treatment process). The permeated water obtained by the reverse osmosis membrane treatment is discharged as treated water through the permeated water pipe 42, and the concentrated water is discharged through the concentrated water pipe 44.

As a result of extensive studies, the inventors of the present invention have found that the permeability of a bactericide containing a bromine-based oxidizing agent or a chlorine-based oxidizing agent and a sulfamic acid compound increases with the concentration of ammonia in the water to be treated. Thus, as the pretreatment of the reverse osmosis membrane treatment, permeation of the reverse osmosis membrane of the bactericide containing the chlorine-based oxidizing agent or the bromine-based oxidizing agent and the sulfamic acid compound can be suppressed by reducing the ammonia concentration in the water to be treated. In particular, when the ammonia concentration in the ammonia-reduced water is 5 mg / liter or less, the effect of reducing the bactericide permeability by ammonia reduction is effective.

The ammonia reduction apparatus 30 is not particularly limited as long as it can reduce the amount of ammonia (ammonium ion) in the water to be treated. Examples of the ammonia reduction apparatus 30 include an ammonia stripping apparatus for performing ammonia stripping treatment, an ammonia decomposition apparatus for performing an ammonia decomposition treatment by an oxidizing agent, and a pretreatment by a reverse osmosis membrane. Among them, the ammonia stripping treatment apparatus for carrying out the ammonia stripping treatment from the viewpoints that there is little increase in the slime risk, that the kinds of the chemicals to be used are not increased by using the chemicals such as the sterilizing agent used as the oxidant, An ammonia decomposition treatment apparatus that performs an ammonia decomposition treatment by an oxidizing agent is preferable.

The ammonia stripping treatment is a treatment method in which ammonia in the ammonia-containing water is moved to the gas side by adding an alkali solution to the ammonia-containing water, warming it, passing it through a column filled with the packing, and bringing it into contact with steam and air.

The ammonia stripping treatment apparatus includes, for example, a perforated plate or a packing in the interior of the distillation column, in which the ammonia-containing water is introduced from the upper portion of the distillation tower, the steam is sucked from the lower portion, Free ammonia in the water is poured into the vapor side. The immobilized ammonia gas may be decomposed further. Examples of the ammonia gas decomposition treatment include a method of decomposing into harmless nitrogen through a catalyst reaction column packed with a catalyst, a method of converting ammonium sulfate into sulfuric acid by reaction with sulfuric acid, and recovering and reusing ammonia water.

The pH in the ammonia stripping treatment is preferably 10 or more, more preferably 10.5 or more, and further preferably 10.5 to 12. If the pH in the ammonia stripping treatment is less than 10, the fraction of free ammonia (NH ₃ ) is lowered and the removal efficiency of ammonia may be lowered. If the pH in the ammonia stripping treatment is more than 12, there is a possibility that the perforated plate or the packing in the distillation column in the ammonia stripping treatment may be deteriorated, but the cost of the alkali chemicals may increase.

Since the ammonia stripping treatment is more efficient at higher temperatures, it is preferable to raise the temperature of the water by 40 to 100 占 폚, preferably 80 to 100 占 폚, by steam.

Examples of the oxidizing agent used for the ammonia decomposition treatment by the oxidizing agent include a chlorinated oxidizing agent, a brominated oxidizing agent, a stabilized hypochlorous acid composition containing a bromine-based oxidizing agent and a sulfamic acid compound, a stabilized hypochlorous acid composition containing a chlorinated oxidizing agent and a sulfamic acid compound And a stabilized hypobromous acid composition and a stabilized hypochlorous acid composition are preferable. Examples of the chlorine-based oxidizing agent, the bromine-based oxidizing agent, the stabilized hypochlorous acid composition, and the stabilized hypochlorous acid composition include the chlorine-based oxidizing agent, the bromine-based oxidizing agent, the stabilized hypochlorous acid composition and the stabilized hypochlorous acid composition. As the oxidizing agent used in the ammonia decomposition treatment, it is preferable that the oxidizing agent is present in the ammonia reducing water at the end of the ammonia reducing step. It is possible to use an oxidizing agent such as a sterilizing agent which is present in ammonia reducing water and use an oxidizing agent in an amount larger than that required for ammonia decomposition so that the oxidizing agent remaining in the ammonia decomposing treatment can also act as a sterilizing agent in the downstream reverse osmosis membrane treating apparatus have.

The amount of the oxidizing agent to be used in the ammonolysis process, and preferably not less than target ammonium nitrogen (NH ₄ -N) to the molar concentration of the active chlorine concentration of the effective molar concentration of halogen in terms of the ratio of the number of 1.6, 2.0 or higher Is more preferable. The larger the ratio is, the higher the effect of reducing ammonia is. Since the ratio of the molar concentration of the effective halogen in terms of the effective chlorine concentration to the molarity of ammonia nitrogen in the for-treatment water is 2.0 or more, the oxidizing agent remaining in the ammonia decomposition treatment can be also used as the disinfectant in the subsequent reverse osmosis membrane treating apparatus . The upper limit of the molarity ratio is, for example, 100 or less.

The pH in the ammonia decomposition treatment by the oxidizing agent is, for example, in the range of 3 to 10, and preferably in the range of 4 to 9. [ If the pH in the ammonia decomposition treatment is less than 3, the decomposition effect of ammonia nitrogen may be lowered. If the pH is more than 10, it may be necessary to adjust the pH to neutrality in order to improve the blocking rate of the reverse osmosis membrane at the subsequent stage .

The temperature in the ammonia decomposition treatment with the oxidizing agent is, for example, in the range of 0 占 폚 to 100 占 폚, and preferably in the range of 0 占 폚 to 40 占 폚. If the temperature in the ammonia decomposition treatment is less than 0 占 폚, the treated water may be frozen in some cases. If the temperature exceeds 100 占 폚, the oxidizing agent or ammonia may volatilize and the ammonia decomposition efficiency may decrease.

The concentration of ammonia in the water to be treated in the ammonia reduction process is, for example, in the range of 0.1 mg / l to 500 mg / l, and preferably in the range of 0.1 mg / l to 30 mg / l.

In the water treatment apparatus and method using the reverse osmosis membrane according to the embodiment of the present invention, a bactericide containing a bromine-based oxidizing agent or a chlorine-based oxidizing agent and a sulfamic acid compound is present in ammonia-reduced water with reduced ammonia by the ammonia- . &Quot; A bactericide comprising a bromine-based oxidizing agent and a sulfamic acid compound " may be a sterilizing agent containing a stabilized hypobromous acid composition comprising a mixture of " bromine-based oxidizing agent " and "Quot; reaction product of the compound " of the present invention. A " bactericide containing a chlorine-based oxidizing agent and a sulfamic acid compound " may be a bactericide containing a stabilized hypochlorous acid composition comprising a mixture of " chlorine-based oxidizing agent " and " &Lt; / RTI &gt; may be a sterilizing agent containing a stabilized hypochlorous acid composition.

That is, in the water treatment apparatus and method using the reverse osmosis membrane according to the embodiment of the present invention, a mixture of the "bromine-based oxidizing agent" and the "sulfamic acid compound" or the "chlorinated oxidizing agent" and the "sulfamic acid compound" A mixture is present. By this, it is considered that a stabilized hypobromous acid composition or a stabilized hypochlorous acid composition is produced in ammonia-reduced water.

In the water treatment apparatus and method using the reverse osmosis membrane according to the embodiment of the present invention, a stabilized hypobromous acid composition, which is a reaction product of a bromine-based oxidizing agent and a sulfamic acid compound, or a " There is present a stabilized hypochlorous acid composition which is " the reaction product of the compound ".

Specifically, in the water treatment apparatus and method using the reverse osmosis membrane according to the embodiment of the present invention, the concentration of ammonia in the aqueous ammonia reduced water is increased by adding "bromine", "bromine chloride", "hypochlorous acid" or "sodium hypochlorite" Reactant " and " sulfamic acid compound " are present. Alternatively, a mixture of " hypochlorous acid " and " sulfamic acid compound &quot; is present in the ammonia reducing water.

Further, in the water treatment apparatus and method using the reverse osmosis membrane according to the embodiment of the present invention, for example, the reaction product of bromine and sulfamic acid compound, the reaction of bromine chloride and sulfamic acid compound There is present a stabilized hypobromous acid composition which is a reaction product of hypobromous acid and a sulfamic acid compound or a reaction product of sodium bromide and hypochlorous acid and a sulfamic acid compound. Alternatively, a stabilized hypochlorous acid composition is present in the ammonia reduction water, which is a "reaction product of hypochlorous acid and a sulfamic acid compound".

In the water treatment apparatus and method using the reverse osmosis membrane according to the present embodiment, although the stabilized hypobromous acid composition or the stabilized hypochlorous acid composition exhibits a slime suppressing effect equal to or higher than that of the chlorinated oxidizing agent such as hypochlorous acid, , The deterioration effect on the reverse osmosis membrane is low, so that the oxidation deterioration of the reverse osmosis membrane can be suppressed while suppressing fouling in the reverse osmosis membrane. For this reason, the stabilized hypobromous acid composition or the stabilized hypochlorous acid composition used in the water treatment apparatus and method using the reverse osmosis membrane according to the present embodiment is a water treatment apparatus and method for treating ammonia-containing water to be treated with a reverse osmosis membrane It is suitable as a slime inhibitor to be used.

Among the water treatment apparatus and method using the reverse osmosis membrane according to the present embodiment, in the case of " a bactericide containing a bromine-based oxidizing agent and a sulfamic acid compound ", there is no chlorine-based oxidizing agent. When a chlorine-based oxidizing agent is contained, generation of chloric acid is a concern.

When the " bromine-based oxidizing agent " is bromine in the water treatment apparatus and method using the reverse osmosis membrane according to the present embodiment, the influence of deterioration on the reverse osmosis membrane is remarkably low because no chlorine-based oxidizing agent is present.

In the water treatment apparatus and method using the reverse osmosis membrane according to the present embodiment, for example, "bromine-based oxidizing agent" or "chlorine-based oxidizing agent" and "sulfamic acid compound" may be injected into the ammonia reducing water by a drug injection pump or the like. The "bromine-based oxidizing agent" or "chlorine-based oxidizing agent" and "sulfamic acid compound" may be separately added to the ammonia reducing water, or may be added to the ammonia reducing water after mixing the undiluted solutions.

Further, for example, the reaction product of the bromine-based oxidizing agent and the sulfamic acid compound or the reaction product of the chloric oxidizing agent and the sulfamic acid compound may be injected into the ammonia-reduced water by a drug injection pump or the like.

In the water treatment apparatus and method using the reverse osmosis membrane according to the present embodiment, the equivalent ratio of the "sulfamic acid compound" to the equivalent of "bromine-based oxidizer" or "chlorine-based oxidizer" is preferably 1 or more, Is more preferable. If the ratio of the equivalent amount of the "sulfamic acid compound" to the equivalent amount of the "bromine-based oxidizing agent" or "chlorine-based oxidizing agent" is less than 1, there is a possibility of deteriorating the film, and if exceeding 2, the production cost may increase.

The total chlorine concentration in contact with the reverse osmosis membrane is preferably 0.01 to 100 mg / l 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 reverse osmosis membrane and corrosion such as piping may occur.

In the water treatment apparatus and method using the reverse osmosis membrane according to the present embodiment, the ammonium ion concentration in the ammonia reduced water is preferably 5 mg / liter or less, more preferably 1 mg / liter or less. If the ammonium ion concentration in the ammonia reducing water exceeds 5 mg / L, the bactericide easily permeates through the reverse osmosis membrane.

The ratio (ammonia concentration (mg / l) / bactericide concentration (total chlorine concentration: mg / l)) of the concentration of ammonia to the total chlorine concentration in the ammonia reduction water is, for example, in the range of 0.01 to 50. If the ratio of the concentration of ammonia to the total chlorine concentration in the ammonia reduction water is less than 0.01, the bactericide is sufficiently blocked by the reverse osmosis membrane, so there is no effect of further ammonia reduction. On the other hand, if it exceeds 50, The bactericide permeability is sufficiently high and the effect of reducing the permeability may not be seen.

In the water treatment apparatus and method using the reverse osmosis membrane according to the present embodiment, more alkali may be present in the ammonia reduced water.

In the water treatment apparatus and method using the reverse osmosis membrane according to the present embodiment, it is preferable that the pH of ammonia reduction water supplied to the reverse osmosis membrane treatment apparatus having a reverse osmosis membrane is 5.5 or more, more preferably 6.0 or more, Is more preferable. If the pH of the ammonia reduction water is less than 5.5, the permeation water may be lowered. The upper limit of the pH of the ammonia-reduced water is not particularly limited as long as it is not higher than the upper limit pH of application (for example, pH 10) of a conventional reverse osmosis membrane. However, considering scale precipitation of hardness components such as calcium, For example, 9.0 or less. When the water treatment apparatus and method using the reverse osmosis membrane according to the present embodiment is used, deterioration of the reverse osmosis membrane and deterioration of water quality of the treated water (permeated water) are suppressed by operating the pH of the ammonia- It is possible to secure sufficient permeated water while exhibiting the effect.

In the reverse osmosis membrane treating apparatus, when a scale occurs at a pH of 5.5 or lower of the ammonia-reduced water, a dispersant may be used in combination with the above-mentioned bactericide in order to suppress the scale. Examples of the dispersing agent include polyacrylic acid, polymaleic acid, and phosphonic acid. The amount of the dispersant to be added to the ammonia reduction 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 not more than the solubility and the Langage index, which is an index of calcium scale, And adjusting the operating conditions such as the recovery rate.

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

The water treatment apparatus and method using the reverse osmosis membrane according to the present embodiment are particularly considered to be applied to drainage recovery, for example, recovery of the electronic industrial wastewater. The electronic industrial wastewater often contains low-molecular organic matter, and is a flow that collects the wastewater. As shown in Fig. 7, the biological wastewater treatment system 50 includes a biological treatment system (for example, The flow including the water treatment apparatus 3 including the ammonia reduction apparatus 30 and the reverse osmosis membrane treatment apparatus 34 applied to the water treatment method using the reverse osmosis membrane according to the present embodiment do.

The water treatment system 5 shown in Fig. 7 includes a biological treatment device 50, a biological treatment water tank 52, a membrane treatment device 54 as a membrane treatment means, a membrane treatment tank 58, , And the water treatment device (3). The water treatment system 5 may include the second reverse osmosis membrane treatment device 60 as the second reverse osmosis membrane treatment means.

In the water treatment system 5, for example, the electronic industrial wastewater as raw water is fed to the biological treatment apparatus 50, and biological treatment is performed in the biological treatment apparatus 50 (biological treatment step). The biotreatment water subjected to the biological treatment is stored in the biological treatment water tank 52 as necessary and then sent to the membrane treatment apparatus 54. The membrane treatment apparatus 54 is provided with a membrane treatment (Membrane treatment process). The film-treated membrane treatment water is stored in the membrane treatment tank 58 as required and then supplied to the ammonia reduction apparatus 30 of the water treatment apparatus 3 as water to be treated so as to be supplied to the ammonia reduction apparatus 30 , And ammonia is reduced (ammonia reduction process).

The ammonia reduction water whose ammonia has been reduced by the ammonia reduction apparatus 30 is fed to the ammonia reduction water tank 32 as required and stored. In the ammonia reducing water tank 32, a bromine-based oxidizing agent or a bactericidal agent containing a chlorine-based oxidizing agent and a sulfamic acid compound is added to the ammonia-reduced water to provide a sterilizing agent (a bactericide addition step). The bactericide may be added to the piping before and after the ammonia reduction water tank 32.

The sterilizing agent-containing water containing the sterilizing agent is supplied to the reverse osmosis membrane treatment device 34, and the reverse osmosis membrane treatment is performed in the reverse osmosis membrane treatment device 34 (reverse osmosis membrane treatment step). The permeated water obtained by the reverse osmosis membrane treatment is discharged as treated water through the permeated water pipe, and the concentrated water is discharged through the concentrated water pipe. The permeated water obtained by the reverse osmosis membrane treatment is discharged outside the system. The concentrated water may be discharged out of the system, fed to the second reverse osmosis membrane treating device 60 as required, and further treated with reverse osmosis membrane in the second reverse osmosis membrane treating device 60 Reverse osmosis membrane treatment process). The concentrated water obtained by the second reverse osmosis membrane treatment is discharged outside the system. The permeated water may be discharged out of the system, fed to the ammonia reduction water tank 32 if necessary, and circulated.

The water treatment system 5 shown in Fig. 7 exemplifies the biological treatment system 56 having the biological treatment apparatus 50, the biological treatment water tank 52 and the membrane treatment apparatus 54 separately, A combined membrane separation activated sludge device (MBR) may be used.

In the water treatment system 5 shown in Fig. 7, the low-molecular organic substances contained in the raw water are decomposed by biological treatment, the biomass and the like are blocked by a membrane treatment device 54 having a detoxifying membrane, Ammonia is reduced in the apparatus 30, and the reverse osmosis membrane treating device 34 blocks various ions and remaining organic substances to obtain treated water (permeated water). In such drainage, the drainage water itself contains ammonia, or ammonia is often generated by biological treatment. For example, biological treatment of waste water containing tetramethylammonium hydroxide as an organic matter tends to generate ammonia.

At this time, biofouling of the reverse osmosis membrane at the downstream is concerned by the biological metabolites generated by the biological treatment or the low molecular organic matter remaining after the biological treatment. Although hypochlorous acid having a high sterilizing power may be used, hypochlorous acid may deteriorate a polyamide-based reverse osmosis membrane, which has become mainstream in recent years. It is also considered to form an activated carbon tower or a reducing agent drug introduction site at the front end of the reverse osmosis membrane, but all of the initial operation costs are problematic. Thus, in the water treatment system 5, ammonia is reduced in the ammonia reduction apparatus, and a bactericidal agent including a bromine-based oxidizing agent or a chlorine-based oxidizing agent and a sulfamic acid compound is present in the ammonia reduced water, It is difficult to oxidize and deteriorate the reverse osmosis membrane of the system, the rate of blocking in the reverse osmosis membrane is high, and the effect on the treated water (permeated water) quality in the downstream is small.

When the bactericide is added to the treated water as described above, deterioration of the treated water becomes a problem. Therefore, in the water treatment apparatus and method using the reverse osmosis membrane according to the present embodiment, as the pretreatment of the reverse osmosis membrane treatment, the sterilizing agent is rarely detected in the permeated water by reducing the ammonia concentration in the water to be treated, Permeation of the permeable membrane is suppressed.

At this time, it is preferable to set the pH of the ammonia-reduced water supplied to the reverse osmosis membrane treating device 34, that is, the operating pH of the reverse osmosis membrane treating device 34 to 9 or less. On the alkali side exceeding pH 9, the desalination rate of the reverse osmosis membrane is lowered, and the oxidizing power of the bactericide may be lowered. When the pH of ammonia-reduced water supplied to the reverse osmosis membrane treatment device 34 is 9 or less, the water quality of the RO permeated water is maintained more favorably, and slime generation is further suppressed.

In the flow of drainage such as the water treatment system 5, it is general to install a second reverse osmosis membrane treatment device (brine RO) 60 in order to increase the water recovery rate. The second reverse osmosis membrane treatment device 60 uses the concentrated water of the reverse osmosis membrane treatment device 34 as raw water, transfers the permeated water to the ammonia reduction water tank 32, and discharges the concentrated water out of the system. If the permeability of the sterilizing agent is low in the reverse osmosis membrane treating device 34, the second reverse osmosis membrane treating device 60 is also liable to generate slime, and if the sterilizing agent component remains in the raw water of the second reverse osmosis membrane treating device 60 . A large amount of the bactericide component remains in the raw water of the second reverse osmosis membrane treating device 60 and the occurrence of slime in the second reverse osmosis membrane treating device 60 is suppressed.

In the water treatment system 5 of Fig. 7, biological treatment is described as an example of pretreatment of reverse osmosis membrane treatment. However, in the pretreatment step of reverse osmosis membrane treatment, biological treatment, coagulation treatment, coagulation sedimentation treatment, A combination of two or more of biological, physical or chemical pretreatment such as treatment, membrane separation treatment, activated carbon treatment, ozone treatment, ultraviolet irradiation treatment, and the like may be carried out as necessary.

In the water treatment apparatus 3, a pump, a safety filter, a flow rate measuring device, a pressure measuring device, a temperature measuring device, an oxidation-reduction potential (ORP) measuring device, a residual chlorine measuring device, , a pH measuring device, an energy recovery device, and the like may be provided as needed.

In the water treatment system 5, scale inhibitors other than the stabilized hypobromous acid composition or the stabilized hypochlorous acid composition, the pH adjuster, the biological treatment water tank 52, pipings before and after it, the membrane treatment water tank 58, Treated water, membrane treated water, and ammonia-reduced water in at least one of the piping before and after the piping, the piping before and after the piping, the ammonia reduction water tank 32, and the piping before and after the pipeline.

<Disinfectant>

The bactericide according to the present embodiment contains a stabilized hypobromous acid composition or a stabilized hypochlorous acid composition containing a mixture of "bromine-based oxidizing agent or chlorine-based oxidizing agent" and "sulfamic acid compound", and may further contain an alkali.

Further, the bactericide according to the present embodiment is a stabilized hypobromous acid composition comprising a " reaction product of a bromine-based oxidizing agent and a sulfamic acid compound " or a stabilized hypobromous acid composition comprising a " reaction product of a chlorine- And may further contain an alkali.

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

As a commercially available product of the stabilized hypochlorous acid composition containing a chlorine-based oxidizing agent and a sulfamic acid compound, for example, "Kuribata IK-110" manufactured by Kurita Kogyo Co., Ltd. can be mentioned.

As the bactericide according to the present embodiment, bromine and a compound containing a sulfamic acid compound (containing a mixture of a bromine and a sulfamic acid compound), for example, bromine and A mixture of a sulfamic acid compound and an alkali and water or a reaction product of a bromine and a sulfamic acid compound, for example, a reaction product of a bromine and a sulfamic acid compound, and an alkali and water are preferable.

Among the bactericides according to the present embodiment, the bactericide containing a stabilized hypobromic acid composition comprising a bromine-based oxidizing agent and a sulfamic acid compound, in particular, a sterilizing agent containing a stabilized hypobromous acid composition containing bromine and a sulfamic acid compound, Compared with a bactericide (chlorosulfamic acid and the like) containing an oxidizing agent and a sulfamic acid compound, remarkable film deterioration such as hypochlorous acid having a high oxidizing power, high slush deterring ability and slime peeling force, There is almost nothing to cause. At the normal use concentration, the influence on the film deterioration can be substantially ignored. Therefore, it is the most suitable as a bactericide.

Unlike hypochlorous acid, the bactericide according to the present embodiment does not substantially permeate the reverse osmosis membrane and has little influence on the quality of treated water. In addition, since concentration can be measured in the field such as hypochlorous acid, more accurate concentration control is possible.

The pH of the bactericide is, for example, more than 13.0, more preferably more than 13.2. When the pH of the bactericide is 13.0 or less, the effective halogen in the bactericide may become unstable.

The concentration of the Bromic acid in the bactericide is preferably less than 5 mg / kg. If the concentration of bromic acid in the bactericide is 5 mg / kg or more, the concentration of bromate ion in the RO permeate water may be increased.

&Lt; Preparation method of bactericide &

The bactericide according to the present embodiment is obtained by mixing a bromine-based oxidizing agent or a chlorine-based oxidizing agent with a sulfamic acid compound, and further mixed with an alkali.

Examples of a method for producing a sterilizing agent containing a stabilized hypobromic acid composition containing bromine and a sulfamic acid compound include a step of adding bromine to a mixed solution containing water, an alkali and a sulfamic acid compound under an inert gas atmosphere, or And 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 the presence of an inert gas atmosphere or under an inert gas atmosphere, the bromic acid ion concentration in the bactericide is lowered and the bromic acid ion concentration in the RO permeated water is lowered.

The inert gas to be used is not limited, but at least one of nitrogen and argon is preferable from the standpoint of production and the like, and nitrogen is preferable from the viewpoint of manufacturing 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 during the reaction of bromine exceeds 6%, the amount of bromic acid produced in the reaction system sometimes increases.

The addition amount of bromine is preferably 25 wt% or less, more preferably 1 wt% or more and 20 wt% or less with respect to the total amount of the bactericide. If the addition rate of bromine exceeds 25 wt% with respect to the total amount of the bactericide, the amount of the produced bromic acid in the reaction system may be increased. If it is less than 1% by weight, the sterilizing power may be poor.

The reaction temperature at the time of bromine addition is preferably controlled within the range of 0 占 폚 to 25 占 폚, but from the viewpoint of production cost and the like, it is more preferable to control the reaction temperature within the range of 0 占 폚 to 15 占 폚. When the reaction temperature at the time of bromine addition exceeds 25 DEG C, the amount of the produced bromic acid in the reaction system sometimes increases. When the reaction temperature is lower than 0 DEG C, the reaction 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.

[Preparation of stabilized hypobromic acid composition (composition 1)] [

Under the nitrogen atmosphere, the stabilized hypobromic acid composition (composition) was prepared by mixing liquid remnants of bromine: 16.9 wt%, sulfamic acid: 10.7 wt%, sodium hydroxide: 12.9 wt%, potassium hydroxide: 3.94 wt% Composition 1) was prepared. The pH of the stabilized hypobromous acid composition was 14 and the total chlorine concentration was 7.5% by weight. A detailed preparation method of the stabilized hypobromous acid composition is as follows.

1436 g of water and 361 g of sodium hydroxide were added and mixed 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% After adding 300 g of sulfamic acid and mixing, 473 g of liquid bromine was added while maintaining the temperature of the reaction solution at 0 to 15 캜, and 230 g of a 48% potassium hydroxide solution was added, To obtain a desired stabilized hypochlorous acid composition (Composition 1) having a sulfamacic acid content of 10.7%, bromine content of 16.9% and an equivalent ratio of sulfamic acid to equivalents of bromine of 1.04. The pH of the obtained solution was 14 as measured by a glass electrode method. The bromine content in the obtained solution was 16.9% as determined by a method of redox titration using bromine in the form of potassium iodide and then sodium thiosulfate. The bromine content was 100.0% of the theoretical content (16.9%). The oxygen concentration in the reaction vessel at the time of the bromine reaction was measured using "Oxygen Monitor JKO-02 LJDII" manufactured by Zico Co., Ltd. Also, the concentration of bromic acid was less than 5 mg / kg.

The pH was measured under the following conditions.

Electrode type: Glass electrode type

pH meter: IOL-30 type manufactured by DKK-TOA CORPORATION

Calibration of the electrode: Two-point calibration of neutral pH (6.86) standard solution (second grade) manufactured by Kanto Chemical Co., Ltd. and standard solution (second grade) of borate salt pH 9.18 manufactured by Kanto Kagaku Co., Ltd.

Measuring temperature: 25 ° C

Measured value: The electrode was immersed in the measuring solution, and the value obtained after the stabilization was used as the measured value. The average value

[Preparation of stabilized hypochlorous acid composition (Composition 2)] [

A stabilized hypochlorous acid composition (Composition 2) was prepared by mixing 12% sodium hypochlorite aqueous solution: 50% by weight, sulfamic acid: 12% by weight, sodium hydroxide: 8% by weight, and water: Composition 2 had a pH of 13.7 and a total chlorine concentration of 6.2% by weight.

[Measurement of zeta potential of reverse osmosis membrane]

The zeta potential of the reverse osmosis membrane was obtained using a zeta potential / particle size measurement system ELSZ series manufactured by Otsuka Electronics Co., Ltd. The zeta potential of the reverse osmosis membrane was calculated from the electro-penetration plots measured from the equation of Himori, Okamoto, and the formula of Smoluchowski.

(Expression of Mori, Okamoto)

_{U obs (z) = AU 0} (z / b) 2 + ΔU 0 (z / b) + (1-A) U 0 + U p

From here,

z: distance from the cell center position

U _obs (z): the apparent mobility at the z-position in the cell

A: 1 / [(2/3) - (0.420166 / K)]

K = a / b: 2a and 2b are the lengths of the cross section of the cell cross section, and a> b

U _p : True mobility of particles

U ₀ : Average mobility on the upper and lower surfaces of the cell

ΔU ₀ : Difference in mobility on the upper and lower surfaces of the cell

(Expression of Small Rhoffsky)

ζ = 4πηU / ε

here,

U: Electricity mobility

ε: permittivity of solvent

η: viscosity of solvent

A 10 mM NaCl aqueous solution (pH of about 5.4) was used as a measuring solution. Two pairs of the aqueous solution and the sample were prepared for each sample, and the pH was acidic (pH 2, 3, 4, 5, 6, 7) on one side and alkaline (pH 8, 9) And the zeta potential at each pH was measured. The physical properties of the solvent were pure water (refractive index: 1.3328, viscosity: 0.8878, dielectric constant: 78.3) at 25 캜.

[Test conditions and test method]

The permeability of the bactericide was measured in a flat membrane test. As the flat membrane cell, a Membrane Master C70-F flow flat membrane test cell manufactured by Nitto Denko Co., Ltd. was used. As the flat membrane, reverse osmosis membranes ES15, ES10C, LFC3 manufactured by Nitto Denko Corporation, reverse osmosis membrane OFR625 manufactured by Organo Corp., and reverse osmosis membrane TML20 manufactured by Toray Co., Ltd. were used. The LFC3 from Nitto Denko is a typical neutral membrane. ES10C manufactured by Nitto Denko is a membrane which has been sold as a cationic subordinate film. TML20 manufactured by Toray Industries Inc., OFR625 manufactured by Organo Corporation is a neutral film, and ES15 manufactured by Nitto Denko Corporation is an anion sublayer. The flat membrane was circular and had a diameter of 75 mm. The flow is shown in Fig.

The test water (for-treatment water) of the flat membrane test was prepared by adding a sterilizing agent to water obtained by dissolving 500 mg / L of sodium chloride in pure water and adjusting it with hydrochloric acid or sodium hydroxide so as to have a pH of 7.0. The concentration of the bactericide was added so that the total chlorine concentration was about 3 to 10 mg / l. The water temperature was adjusted to 25 ± 1 ℃ using a cooler. The operation pressure of the reverse osmosis membrane was 0.75 MPa. The feed rate to the reverse osmosis membrane was 5 liters / minute. After passing water for about 3 hours, the bactericide concentration (total chlorine concentration) of the water to be treated and the permeated water was measured, and the permeability of the bactericide was obtained. The total chlorine concentration was measured (as mg / l, Cl ₂ ) by the total chlorine measurement method (DPD (diethyl-p-phenylenediamine) method) by using a multi-item water quality analyzer DR / to be.

Ammonium chloride was added so that the ammonia concentration was 0 mg / L, 1 mg / L, 5 mg / L and 10 mg / L, and the concentration of the water to be treated (total chlorine concentration) Chlorine concentration) and transmittance were measured. The measurement results are shown in Table 1.

&Lt; Example 1 >

In Example 1, a stabilized hypobromous acid composition (Composition 1) was used as a bactericide, and ammonium ion concentration of 10 mg / L (Example 1-1), 5 mg / L (Example 1-2) (%) Of the bactericide in each zeta potential (㎷) in the case of (Example 1-3). The results are shown in Fig.

&Lt; Comparative Example 1 &

In Comparative Example 1, the stabilized hypobromous acid composition (Composition 1) was used as a bactericide, and the bactericidal permeability (%) in each zeta potential ()) at an ammonium ion concentration of 0 mg / Were measured. The results are shown in Fig.

In Comparative Example 1, the permeability of the bactericide is low and the dependency of the permeability on the zeta potential is hardly observed. However, in Example 1, the permeability of the bactericide is high, and the higher the zeta potential, the lower the permeability is. This tendency becomes even greater when the ammonium ion concentration is 5 mg / L or more.

&Lt; Example 2 >

(Example 2-1), TML20 (Example 2-2), and LFC3 (Example 2-4)) and the neutral membranes (Example 2-1), TML20 (Example 2-2), and LFC3 (Example 2-4) were used as a sterilizing agent and a stabilized hypobromous acid composition The permeability of the bactericide in the cationic sub-membrane (ES10C (Example 2-3)) was measured. The correlation between the bactericidal permeability (%) and the ammonium ion concentration (mg / l) is shown in Fig.

&Lt; Comparative Example 2 &

In Comparative Example 2, the stabilized hypobromous acid composition (Composition 1) was used as the bactericide, and the bactericidal permeability in the anion-under-charged membrane (ES15 (Comparative Example 2-1)) was measured. The correlation between the bactericidal permeability (%) and the ammonium ion concentration (mg / l) is shown in Fig.

The permeability of the germicide is lower in Example 2 than in Comparative Example 2. Particularly, when the ammonium ion concentration is 5 mg / L or more, the difference in the transmittance increases.

&Lt; Example 3 >

In Example 3, the stabilized hypochlorous acid composition (Composition 2) was used as the bactericide, and the bactericidal permeability in the neutral membrane (LFC3 (Example 3-1)) was measured in the same manner as in Example 2. [ The correlation between the bactericidal permeability (%) and the ammonium ion concentration (mg / l) is shown in Fig.

&Lt; Comparative Example 3 &

In Comparative Example 3, the stabilized hypochlorous acid composition (Composition 2) was used as the bactericide, and the bactericidal permeability in the anion-under-charged membrane (ES15 (Comparative Example 3-1)) was measured in the same manner as in Comparative Example 2. The correlation between the bactericidal permeability (%) and the ammonium ion concentration (mg / l) is shown in Fig.

In the chlorine-based stabilized hypochlorous acid composition, the permeability of the sterilizing agent is lower when the neutral membrane and the cationic charged membrane are used. In addition, when the ammonium ion concentration is 5 mg / L or more, the difference in the transmittance increases.

As described above, in the water treatment method of treating the for-treatment water containing ammonia with the reverse osmosis membrane by the method of the embodiment, the permeation of the reverse osmosis membrane of the bactericide containing the chlorine-based oxidizing agent or the bromine- Could.

&Lt; Example 4, Comparative Example 4 >

[Test conditions and test method]

The permeability of the bactericide was measured in a flat membrane test. As the flat membrane cell, a Membrane Master C70-F flow flat membrane test cell manufactured by Nitto Denko Co., Ltd. was used. As the flat membrane, a reverse osmosis membrane ES15 (Comparative Example 4) and LFC3 (Example 4) manufactured by Nitto Denko Co., Ltd. were used. (Zeta potential: -35 mV) manufactured by Nitto Denko Corporation, and neutral film (zeta potential: -1.3 mV) manufactured by Nitto Denko Corporation. The flat membrane was circular and had a diameter of 75 mm. The flow is shown in Fig.

The test water (treated water) of the flat membrane test was prepared by dissolving 500 mg / L of sodium chloride in pure water and adding a sterilizing agent (Example 4-1, Comparative Example 4-1) or Composition 2 (Example 4- 2, Comparative Example 4-2)) was added, and adjusted with hydrochloric acid or sodium hydroxide to adjust the pH to 7.0. The concentration of the bactericide was added so that the total chlorine concentration was about 3 to 10 mg / l. The water temperature was adjusted to 25 ± 1 ℃ using a chiller. The operation pressure of the reverse osmosis membrane was 0.75 MPa. The feed rate to the reverse osmosis membrane was 5 liters / minute.

Ammonium chloride was added so that the ammonia concentration was 0 mg / L, 1 mg / L, 5 mg / L and 10 mg / L, and after passing for about 3 hours, the concentration of the water to be treated (total chlorine concentration ), Permeate concentration (total chlorine concentration), and permeability were measured. The results of the measurement are shown in Table 2, and the correlation between the bactericide permeability (%) and the ammonium ion concentration (mg / l) is shown in Fig. 8 (Example 1 (Example 4-1 and Comparative Example 4-1)) and Fig. 9 Example 4-2, Comparative Example 4-2).

The permeability of the germicide increased with the concentration of ammonia. In particular, when the ammonia concentration is 5 mg / liter or less, the tendency of the increase of the permeability is relatively large, and it is considered that the pretreatment for reducing the ammonia concentration to 5 mg / liter or less is preferable.

As a kind of the reverse osmosis membrane in this system, it was found that the permeability of the sterilizing agent was lower when the neutral membrane LFC3 was used than the anion lower membrane ES15.

&Lt; Examples 5 to 8 and Comparative Examples 5 and 6 >

The test was performed using the pilot apparatus shown in Fig. In the raw water (for-treatment water), 500 mg / L of sodium chloride was dissolved in purified water and the pH was adjusted to 7.0. As the pH adjusting agent, hydrochloric acid or sodium hydroxide was used. As the reverse osmosis membrane, LFC3 (Examples 5 to 8) or ES15 (Comparative Examples 5 and 6) manufactured by Nitto Denko Co., Ltd. were used, the treated water of raw water was 25 m 3 / d, the supplied water temperature was 25 ° C, MPa. As the bactericide, a stabilized hypobromous acid composition (Composition 1) was used, and the total chlorine concentration was measured as the concentration of the bactericide.

(Examples 5 and 6 and Comparative Example 5)

In Example 5 and Comparative Example 5-1, an ammonia stripping device was used as the ammonia reduction means, and in Example 6 and Comparative Example 5-2, no ammonia stripping device was used. Ammonium chloride was added so that the ammonia concentration of the raw water (for-treatment water) was 200 mg / l, 100 mg / l and 20 mg / l. The liquid temperature for carrying out ammonia stripping was 80 DEG C and the pH was 10. At this time, the ammonia concentration in the water to be treated and the reverse osmosis membrane inlet, the number of reverse osmosis membrane inlet and the bactericide concentration (total chlorine) in the treated water were measured, and the permeability of the bactericide in each condition was calculated. The results are shown in Table 3.

RO
Film type Ammonia concentration in water to be treated
[Mg / l] RO inlet ammonia concentration
[Mg / l] RO inlet sanitizer concentration (total chlorine)
[Mg / l] Treated bactericidal concentration (total chlorine)
[Mg / l] disinfectant
Transmittance
[%] disinfectant
Permeability Example 5-1 LFC3 200 11 9.3 0.5 5.1 0.268 times
(Example 5 / Example 6) Example 6-1 199 8.9 1.7 19 Example 5-2 LFC3 100 5.0 9.8 0.1 1.1 0.069 times
(Example 5 / Example 6) Example 6-2 98 9.4 1.5 16 Example 5-3 LFC3 20 1.1 10.8 0.1 0.5 0.058 times
(Example 5 / Example 6) Example 6-3 19 10.2 0.9 8.6 Comparative Example 5-1 ES15 20 1.1 10.8 0.8 7 0.389 times
(Comparative Example 5-1 / Comparative Example 5-2) Comparative Example 5-2 19 10.2 1.8 18

In Example 5, the permeability of the bactericide could be reduced as compared with Example 6. [ Further, when the ammonia concentration in the for-treatment water is 100 mg / L or less, the ammonia concentration at the inlet of the reverse osmosis membrane becomes 5 mg / L or less, the permeability of the bactericide becomes 0.069 times or less as compared with Example 6, The transmittance can be effectively reduced.

(Examples 7 and 8 and Comparative Example 6)

In Example 7 and Comparative Example 6-1, an oxidizing agent was added as an ammonia reducing means, and no oxidizing agent was added in Examples 8 and 6-2. As the oxidizing agent, a stabilized hypobromous acid composition (Composition 1) added in the reverse osmosis membrane at the downstream was added. Ammonium chloride was added so that the ammonia concentration of the raw water (for-treatment water) was 20 mg / l, 15 mg / l, and 3 mg / l. The concentration of the added oxidizing agent was 10 mg / L as total chlorine and the pH was 7.2. The reaction time for the oxidative decomposition was 30 minutes. The results are shown in Table 4.

RO
Film type Ammonia concentration in water to be treated
[Mg / l] RO inlet ammonia concentration
[Mg / l] RO inlet sanitizer concentration (total chlorine)
[Mg / l] Treated bactericidal concentration (total chlorine)
[Mg / l] disinfectant
Transmittance
[%] disinfectant
Permeability Example 7-1 LFC3 20 6.4 10.8 0.2 2.3 0.267 times
(Example 7 / Example 8) Example 8-1 20 10.2 0.9 8.6 Example 7-2 LFC3 15 4.8 10.8 0.1 1.0 0.056 times
(Example 7 / Example 8) Example 8-2 15 10.3 1.9 18 Example 7-3 LFC3 3 1.0 10.8 0.1 0.5 0.029 times
(Example 7 / Example 8) Example 8-3 8 10.5 1.8 17 Comparative Example 6-1 ES15 3 1.0 10.8 0.8 7 0.412 times
(Comparative Example 6-1 / Comparative Example 6-2) Comparative Example 6-2 8 10.5 1.8 17

In Example 7, the permeability of the germicide could be reduced as compared with Example 8. When the ammonia concentration of the water to be treated is 15 mg / L or less, the ammonia concentration at the inlet of the reverse osmosis membrane becomes 5 mg / L or less, the permeability of the bactericide becomes 0.056 times or less as compared with Example 8, The transmittance can be effectively reduced.

&Lt; Examples 9-1 to 9-5 >

As simulated drainage, ammonia chloride was added to Sagamihara City water having residual chlorine removed with activated carbon so that the concentration of ammonia nitrogen (NH ₄ -N) was 7.8 mg-N / L (0.56 mmol / To prepare an aqueous solution. The pH of the prepared simulated drainage was 7.2. To the simulated drainage, a stabilized hypobromous acid composition (Composition 1) (Examples 9-1 to 9-5) was mixed with 15 mg / l (as Cl ₂ ) (0.21 mmol / l) -1), 40 mg / l (as Cl ₂ ) (0.56 mmol / l) (Example 9-2), 61 mg / l (as Cl ₂ ) (0.87 mmol / ), 79 mg / l (as Cl ₂ ) (1.11 mmol / l) (Example 9-4), 99 mg / l (as Cl ₂ ) (1.40 mmol / , Respectively. The test solution was agitated by a digital stirrer at 500 rpm while changing the ammonia nitrogen (NH ₄ -N) concentration over time (after 10 minutes and after 30 minutes). After 30 minutes, the total chlorine concentration of the test water was measured. The results are shown in Table 5.

The total chlorine concentration was measured (as mg / l, Cl ₂ ) by the total chlorine measurement method (DPD (diethyl-p-phenylenediamine) method) by using a multi-item water quality analyzer DR / to be. The ammonia nitrogen (NH ₄ -N) concentration (mg / l, as N) was determined by a pack test (ammonium type nitrogen, type WAK-NH4) of Kyoritsu Rikagakuken Kagaku Co., The coloring principle of the indocyanine blue absorption spectrophotometry of JIS K 010242.2 was measured.

In Table 5, the molar concentration of the effective halogen in terms of the effective chlorine concentration (the addition amount of the stabilized hypobromous acid composition (relative to the molar concentration of the ammonia nitrogen (NH ₄ -N) in the simulated wastewater before treatment (0.56 mmol / Molar concentration), the effect of reducing ammonia nitrogen is also increased. In particular, the ammonia in the simulated multiple-nitrogen (NH ₄ -N), the molar concentration ratio of 1.6 (addition molar concentration of the stabilized hypochlorite bromate composition) of the molar concentration, in terms of effective chlorine concentration of available halogen in (Example 9-3 ), It became clear that ammonia nitrogen can be almost completely decomposed.

Example 9-1 Example 9-2 Example 9-3 Examples 9-4 Examples 9-5 Additive agent Stabilized hypobromic acid composition (Composition 1) Additive agent
density [Mg / l (as Cl ₂ )] 15 40 61 79 99 [m mol / l (as Cl ₂ )] 0.21 0.56 0.87 1.11 1.40 NH ₄ -N concentration in simulated drainage [Mg / l] 7.8 [m mol / l] 0.56 The ratio of the molar concentration of the additive agent to the NH ₄ -N molar concentration in the simulated drainage 0.4 1.0 1.6 2.0 2.5 NH ₄ -N concentration in simulated drainage
[Mg / l] Before processing 7.8 7.8 7.8 7.8 7.8 After 10 minutes 2.9 2.3 0.9 0 0 30 minutes later 2.5 2.2 0.8 0 0 Total chlorine concentration in simulated drainage
[Mg / l (as Cl ₂ )]
30 minutes later 3.9 4.4 4.5 14.5 32.0

As described above, in the water treatment method of treating the for-treatment water containing ammonia with the reverse osmosis membrane by the method of the embodiment, the permeation of the reverse osmosis membrane of the bactericide containing the chlorine-based oxidizing agent or the bromine- Could.

1, 5: water treatment system 3: water treatment apparatus
10, 50: biological treatment device 12, 52: biological treatment tank
14, 54: membrane treatment device 16, 56: biological treatment system
18, 58: membrane treatment tank 20:
22, 34: reverse osmosis membrane treatment device 24, 60: second reverse osmosis membrane treatment device
26: Reverse osmosis membrane treatment system 30: Ammonia reduction device
32: Ammonia reduction water tank 36: Pipe for treatment water
38: Ammonia reduction water piping 40: Disinfectant-containing water piping
42: Permeated water piping 44: Condensated water piping
46: Disinfection piping

Claims (14)

A water treatment method using a reverse osmosis membrane that treats water to be treated containing ammonia with a reverse osmosis membrane,
Wherein a bromine-based oxidizing agent or a bactericide containing a chlorine-based oxidizing agent and a sulfamic acid compound is present in the water to be treated,
Wherein the reverse osmosis membrane is a neutral membrane or a cation-immobilized membrane. A water treatment method using a reverse osmosis membrane that treats water to be treated containing ammonia with a reverse osmosis membrane,
A sterilizing agent containing bromine and a sulfamic acid compound is present in the water to be treated,
Wherein the reverse osmosis membrane is a neutral membrane or a cation-immobilized membrane. 3. The method according to claim 1 or 2,
Characterized in that the ammonium ion concentration in the for-treatment water is 1 mg / liter or more. 4. The method according to any one of claims 1 to 3,
Characterized in that ammonia in the for-treatment water containing ammonia is reduced, and the bactericide is present in ammonia-reduced water with reduced ammonia. 5. The method of claim 4,
Characterized in that the ammonia concentration of the ammonia-reduced water is 5 mg / liter or less. The method according to claim 4 or 5,
A method for water treatment using a reverse osmosis membrane, characterized by reducing ammonia in the water to be treated containing ammonia by ammonia stripping treatment. The method according to claim 4 or 5,
A method for water treatment using a reverse osmosis membrane, characterized by reducing ammonia in the water to be treated containing ammonia by an ammonia decomposition treatment with an oxidizing agent. A water treatment apparatus using a reverse osmosis membrane for treating ammonia-containing water to be treated with a reverse osmosis membrane,
Wherein a bromine-based oxidizing agent or a bactericide containing a chlorine-based oxidizing agent and a sulfamic acid compound is present in the water to be treated,
Characterized in that the reverse osmosis membrane is a neutral membrane or a cationic anion-exchange membrane. A water treatment apparatus using a reverse osmosis membrane for treating ammonia-containing water to be treated with a reverse osmosis membrane,
A sterilizing agent containing bromine and a sulfamic acid compound is present in the water to be treated,
Characterized in that the reverse osmosis membrane is a neutral membrane or a cationic anion-exchange membrane. 10. The method according to claim 8 or 9,
Characterized in that the ammonium ion concentration in the for-treatment water is 1 mg / liter or more. 11. The method according to any one of claims 8 to 10,
Characterized by comprising ammonia reducing means for reducing the ammonia in the water to be treated containing ammonia, wherein the sterilizing agent is present in the ammonia reducing water in which the ammonia is reduced by the ammonia reducing means, . 12. The method of claim 11,
Characterized in that the ammonia concentration of the ammonia-reduced water is 5 mg / liter or less. 13. The method according to claim 11 or 12,
Characterized in that an ammonia stripping treatment device is provided as the ammonia reducing means. 13. The method according to claim 11 or 12,
The water treatment apparatus using a reverse osmosis membrane, characterized by comprising ammonia decomposition treatment means by an oxidant as the ammonia reduction means.

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