JP2018183751A - Water treatment method and water treatment apparatus using reverse osmosis membrane - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a water treatment method and a water treatment apparatus for treating water to be treated containing ammonia with a reverse osmosis membrane, wherein a bactericide containing a bromine base oxidant and a sulfamic acid compound is inhibited from passing through the reverse osmosis membrane.SOLUTION: The present invention provides a water treatment method for treating water to be treated containing ammonia with a reverse osmosis membrane, wherein a bactericide containing a bromine base oxidant and a sulfamic acid compound is caused to be present in the water to be treated, and the sulfamic acid compound is caused to be present in the bactericide, the water to be treated before causing the bactericide to be present therein, or both of them so that a molar concentration of the sulfamic acid compound is 1.11 times or more of that of bromine in the bactericide.SELECTED DRAWING: None

Description

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

  In a water treatment method using a reverse osmosis membrane (RO membrane), various bactericides (slime inhibitors) are generally used as a measure against biofouling. Chlorine oxidizers such as hypochlorous acid are typical fungicides and are usually added to the front of the reverse osmosis membrane for the purpose of sterilization in the system. Chlorine oxidizers are likely to degrade reverse osmosis membranes, so in general, chlorinated oxidants are reduced and decomposed immediately before reverse osmosis membranes, or chlorine oxidants flow into reverse osmosis membranes intermittently. It is operated by letting.

  Also, a method of adding bromine-based oxidant as a bactericide (slime inhibitor), a reaction product of bromine compound and chlorine-based oxidant, and a mixture or reaction product of sulfamic acid compound to water to be treated (patent document) 1) is known.

  A disinfectant containing a bromine-based oxidant and a sulfamic acid compound has a high disinfecting ability, hardly oxidizes and degrades a polyamide-based reverse osmosis membrane, and has a high rejection rate in the reverse osmosis membrane. ) Effective because it has little effect on quality.

  In Patent Document 2, it is preferable that the ratio of the equivalent of sulfamic acid to the equivalent of bromine is in the range of 1.01 to 1.1 in a fungicide containing bromine and a sulfamic acid compound as bromine-based oxidizing agents. Is described.

Japanese Patent Laying-Open No. 2015-062889 Japanese Patent No. 5918109

  However, it has been found that when the water to be treated contains ammonia (ammonium ions), a part of the bactericide containing the bromine-based oxidizing agent and the sulfamic acid compound permeates the reverse osmosis membrane. For example, when the ammonium ion concentration of to-be-processed water is 10 mg / L, it turned out that the transmittance | permeability of a disinfectant rises to about 20-30%. Ammonium ions are present in electronic industrial wastewater, biologically treated water, groundwater, and the like, and are often contained in water to be treated by reverse osmosis membranes. When the bactericidal agent permeates through the reverse osmosis membrane, the quality of the treated water is deteriorated and the downstream equipment is deteriorated. Therefore, it is desired to suppress the penetration of the bactericidal agent.

  An object of the present invention is to suppress permeation of a bactericide containing a bromine-based oxidant and a sulfamic acid compound through a reverse osmosis membrane in a water treatment method and a water treatment apparatus for treating water to be treated containing ammonia with a reverse osmosis membrane. The present invention provides a water treatment method and a water treatment apparatus.

  The present invention relates to a water treatment method using a reverse osmosis membrane for treating water to be treated containing ammonia with a reverse osmosis membrane, wherein the treatment water contains a bromine-based oxidizing agent and a sulfamic acid compound. And the sulfamic acid compound in the disinfectant, the treated water before the disinfectant is present, or both so that the molar concentration of bromine in the disinfectant is 1.11 times or more. Is a water treatment method using a reverse osmosis membrane.

  Further, the present invention is a water treatment method using a reverse osmosis membrane for treating water to be treated containing ammonia with a reverse osmosis membrane, wherein a bactericidal agent containing bromine and a sulfamic acid compound is contained in the water to be treated. The sulfamic acid compound is present in the disinfectant, the treated water before the disinfectant is present, or both so that the molar concentration of bromine in the disinfectant is 1.11 times or more. This is a water treatment method using a reverse osmosis membrane.

  In the water treatment method using the reverse osmosis membrane, 1.57 times or less of the molar concentration of bromine in the disinfectant in the disinfectant, the water to be treated before the disinfectant is present, or both It is preferable that the sulfamic acid compound is present.

  In the water treatment method using the reverse osmosis membrane, it is preferable that the water to be treated is treated with the reverse osmosis membrane immediately after the disinfectant is present in the water to be treated.

  In the water treatment method using the reverse osmosis membrane, the disinfectant is added to the pipe for passing the treated water through the reverse osmosis membrane, and immediately after the disinfectant is added to the pipe, It is preferable to treat with an osmotic membrane.

  Further, the present invention is a water treatment apparatus using a reverse osmosis membrane for treating the water to be treated containing ammonia with a reverse osmosis membrane, wherein the water to be treated contains a bromine-based oxidizing agent and a sulfamic acid compound. The sulfamine is present so that the molar concentration of bromine in the disinfectant is 1.11 times or more in the disinfectant, in the water to be treated before the disinfectant is present, or both. It is a water treatment apparatus using a reverse osmosis membrane in which an acid compound is present.

  The present invention is also a water treatment apparatus using a reverse osmosis membrane for treating water to be treated containing ammonia with a reverse osmosis membrane, wherein a bactericidal agent containing bromine and a sulfamic acid compound is contained in the water to be treated. The sulfamic acid compound is present in the disinfectant, the treated water before the disinfectant is present, or both so that the molar concentration of bromine in the disinfectant is 1.11 times or more. A water treatment apparatus using a reverse osmosis membrane.

  In the water treatment apparatus using the reverse osmosis membrane, 1.57 times or less of the molar concentration of bromine in the disinfectant in the disinfectant, the water to be treated before the disinfectant is present, or both It is preferable that the sulfamic acid compound is present.

  In the water treatment apparatus using the reverse osmosis membrane, it is preferable that the water to be treated is treated with the reverse osmosis membrane immediately after the disinfectant is present in the water to be treated.

  In the water treatment apparatus using the reverse osmosis membrane, the disinfectant is added to the pipe for passing the water to be treated through the reverse osmosis membrane in a line, and the water to be treated is immediately added to the reverse osmosis membrane. It is preferable to treat with an osmotic membrane.

  In the present invention, in a water treatment method and a water treatment apparatus for treating water to be treated containing ammonia with a reverse osmosis membrane, the permeation of the reverse osmosis membrane of a disinfectant containing a bromine-based oxidant and a sulfamic acid compound is suppressed. Can do.

It is a schematic block diagram which shows an example of the water treatment apparatus using the reverse osmosis membrane which concerns on embodiment of this invention. It is a schematic block diagram which shows the other example of the water treatment apparatus using the reverse osmosis membrane which concerns on embodiment of this invention. It is a schematic block diagram which shows an example of the water treatment system to which the water treatment apparatus using the reverse osmosis membrane which concerns on embodiment of this invention is applied. It is a schematic block diagram of the flat film test apparatus used for evaluation of the transmittance | permeability of a disinfectant in an Example and a comparative example. It is a graph which shows the disinfectant transmittance | permeability (%) with respect to sulfamic acid / bromine (mol / mol) in an Example and a comparative example.

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

<Water treatment method and water treatment apparatus using reverse osmosis membrane>
An example of a water treatment apparatus according to an embodiment of the present invention is schematically shown in FIG.

  A water treatment device 1 shown in FIG. 1 includes a reverse osmosis membrane treatment device 12 as a reverse osmosis membrane treatment means. The water treatment apparatus 1 may include a water tank 10 to be treated for storing the water to be treated containing ammonia.

  In the water treatment apparatus 1, a water treatment pipe 14 is connected to the inlet of the water tank 10 to be treated. The outlet of the water tank 10 to be treated and the inlet of the reverse osmosis membrane treatment device 12 are connected by a water supply pipe 16 to be treated. A permeate pipe 18 is connected to the permeate outlet of the reverse osmosis membrane treatment apparatus 12, and a concentrate water pipe 20 is connected to the concentrate outlet. A bactericide addition pipe 22 is connected to the water tank 10 to be treated.

  The operation of the water treatment method and the water treatment apparatus 1 according to this embodiment will be described.

  In the water treatment apparatus 1, the water to be treated containing ammonia (ammonium ions) is sent to the water tank 10 to be treated and stored through the water pipe 14 to be treated as necessary. In the water tank 10 to be treated, a bactericidal agent containing a bromine-based oxidant and a sulfamic acid compound is added to the water to be treated, and the bactericidal agent is present (bactericidal agent adding step). At this time, the sulfamic acid compound is present in the disinfectant, in the water to be treated before the disinfectant is present, or both so that the molar concentration of bromine in the disinfectant is 1.11 times or more. A disinfectant may be added in the to-be-processed water piping 14, and may be added in the to-be-processed water supply piping 16 like the water treatment apparatus 3 shown in FIG.

  The bactericide-containing water containing the bactericide is supplied to the reverse osmosis membrane treatment device 12 through the treated water supply pipe 16, and the reverse osmosis membrane treatment device 12 performs the 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 18, and the concentrated water is discharged through the concentrated water pipe 20.

  As a result of repeated investigations, the present inventors have previously added an excessive amount of a sulfamic acid compound to a bromine-based oxidant, so that a reverse osmosis membrane of a bactericide containing a bromine-based oxidant and a sulfamic acid compound can be obtained. It has been found that transmission can be suppressed. The sulfamic acid compound may be added in the bactericidal agent, or may be added before the bactericidal agent is added to the water to be treated before the bactericidal agent is present, that is, You may add to both in a disinfectant and to-be-processed water before making a disinfectant exist. Usually, the sulfamic acid compound may be present in the fungicide so as to be 1.11 times or more the molar concentration of bromine in the fungicide.

  At this time, the larger the amount of the sulfamic acid compound present in excess, the more the permeation of the bactericide through the reverse osmosis membrane can be suppressed, but it should be 1.11 times the molar concentration of bromine in the bactericide. By allowing the sulfamic acid compound to exist, the permeation of the reverse osmosis membrane of the bactericidal agent can be suppressed as compared with the prior art, and the sulfamic acid compound is less than 1.57 times the molar concentration of bromine in the bactericidal agent. In the presence of, the penetration of the bactericide through the reverse osmosis membrane can be efficiently suppressed in terms of cost.

  In the water treatment method according to this embodiment, almost no residence time is required. That is, the treated water may be treated with a reverse osmosis membrane immediately after the disinfectant is present in the treated water. Here, “immediately” is, for example, within 10 minutes, preferably within 1 minute. If the sulfamic acid compound is excessively present in the treated water or the sterilizing agent in advance, the sterilizing agent is added to the treated water supply pipe 16 as shown in FIG. It is also possible to add a line. Thereby, the disinfectant addition tank for adding a disinfectant, for example, the to-be-processed water tank 10 does not need to be provided in the example of FIG. 2, and the water treatment apparatus having no disinfectant addition tank also relates to this embodiment. Water treatment methods can be applied. This makes it possible to construct a device that is advantageous in terms of initial cost, device installation area, and the like. In addition, for example, a reverse osmosis membrane treatment apparatus in the second and subsequent stages of two or more stages of reverse osmosis membrane treatment, further comprising at least one reverse osmosis membrane treatment apparatus in the subsequent stage of the reverse osmosis membrane treatment apparatus 12, or a reverse osmosis membrane treatment apparatus The water treatment method according to this embodiment can also be applied to a reverse osmosis membrane treatment apparatus immediately after a deaeration membrane in a reverse osmosis membrane treatment provided with a deaeration membrane in the preceding 12 stages.

  In a water treatment method and a water treatment apparatus using a reverse osmosis membrane according to an embodiment of the present invention, a bactericide containing a bromine-based oxidant and a sulfamic acid compound is present in water to be treated containing ammonia. “A disinfectant containing a bromine-based oxidant and a sulfamic acid compound” is a disinfectant containing a stabilized hypobromite composition containing a mixture of a “bromine-based oxidant” and a “sulfamic acid compound”. Alternatively, it may be a disinfectant containing a stabilized hypobromite composition containing “reaction product of bromine-based oxidant and sulfamic acid compound”.

  That is, in the water treatment method and the water treatment apparatus using the reverse osmosis membrane according to the embodiment of the present invention, a mixture of “bromine-based oxidant” and “sulfamic acid compound” is present in the water to be treated containing ammonia. . Thereby, it is thought that the stabilized hypobromite composition produces | generates in to-be-processed water.

  Further, in the water treatment method and the water treatment apparatus using the reverse osmosis membrane according to the embodiment of the present invention, a stable product that is a “reaction product of a bromine-based oxidant and a sulfamic acid compound” is contained in the water to be treated containing ammonia. A chemical hypobromite composition is present.

  Specifically, in the water treatment method and the water treatment apparatus using the reverse osmosis membrane according to the embodiment of the present invention, in the water to be treated containing ammonia, “bromine”, “bromine chloride”, “hypochlorous acid” or A mixture of “reaction product of sodium bromide and hypochlorous acid” and “sulfamic acid compound” is present.

  Moreover, in the water treatment method and the water treatment apparatus using the reverse osmosis membrane according to the embodiment of the present invention, for example, “reaction product of bromine and sulfamic acid compound”, “bromine chloride” Reaction product of sulfamic acid compound "," Reaction product of hypobromite and sulfamic acid compound "or" Reaction of sodium bromide and hypochlorous acid with sulfamic acid compound " There is a stabilized hypobromite composition that is "product".

  In the water treatment method and water treatment apparatus using the reverse osmosis membrane according to the present embodiment, the stabilized hypobromite composition exhibits a slime suppression effect equivalent to or better than that of a chlorine-based oxidizing agent such as hypochlorous acid. Nevertheless, since the deterioration effect on the reverse osmosis membrane is low as compared with the chlorine-based oxidant, the oxidative deterioration of the reverse osmosis membrane can be suppressed while suppressing fouling in the reverse osmosis membrane. Therefore, the water treatment method using the reverse osmosis membrane according to the present embodiment and the stabilized hypobromite composition used in the water treatment apparatus are water treatment methods for treating water to be treated containing ammonia with a reverse osmosis membrane. And as a slime inhibitor used in water treatment equipment.

  In the water treatment method and the water treatment apparatus using the reverse osmosis membrane according to the present embodiment, the “bactericidal agent containing bromine-based oxidant and sulfamic acid compound” has no chlorine-based oxidant, Deterioration effect is lower. When a chlorinated oxidant is included, there is a concern about the production of chloric acid.

  In the water treatment method and the water treatment apparatus using the reverse osmosis membrane according to the present embodiment, when the “bromine-based oxidant” is bromine, there is no chlorine-based oxidant, so the deterioration effect on the reverse osmosis membrane is significant. Low.

  In the water treatment method and water treatment apparatus using the reverse osmosis membrane according to the present embodiment, for example, “bromine-based oxidant” and “sulfamic acid compound” are injected into the water to be treated containing ammonia by a chemical injection pump or the like. May be. The “bromine-based oxidizing agent” and the “sulfamic acid compound” may be added separately to the water to be treated, or may be added to the water to be treated after being mixed with the stock solutions.

  Further, for example, “reaction product of bromine-based oxidant and sulfamic acid compound” may be injected into the water to be treated containing ammonia by a chemical injection pump or the like.

  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 the amount is less than 0.01 mg / L, a sufficient slime-inhibiting effect may not be obtained. If the amount is more than 100 mg / L, the reverse osmosis membrane may be deteriorated and the piping may be corroded.

  In the water treatment method and the water treatment apparatus using the reverse osmosis membrane according to the present embodiment, the ammonium ion concentration in the water to be treated is preferably 0.01 mg / L or more and 1000 mg / L or less, preferably 0.1 mg / L or more. More preferably, it is 100 mg / L or less. If the ammonium ion concentration in the water to be treated is less than 0.01 mg / L, the bactericidal agent is sufficiently blocked by the reverse osmosis membrane. When it exceeds / L, the disinfectant permeability is high and the permeation suppression effect of the reverse osmosis membrane of the disinfectant may be difficult to appear.

  The ratio of ammonia concentration to total chlorine concentration in the water to be treated (ammonia concentration (mg / L) / disinfectant concentration (total chlorine concentration: mg / L)) is, for example, in the range of 0.01 to 50, and 0 A range of 0.01 to 1.0 is preferable. When the ratio of the concentration of ammonia to the total chlorine concentration in the water to be treated is less than 0.01, the bactericidal agent is sufficiently blocked by the reverse osmosis membrane, so that the permeation suppression effect of the reverse osmosis membrane of the bactericide is difficult to appear. If it exceeds 50, the disinfectant permeability is high and the permeation inhibiting effect of the reverse osmosis membrane of the disinfectant may be difficult to appear.

  Examples of bromine-based oxidizing agents include bromine (liquid bromine), bromine chloride, bromic acid, bromate, and hypobromite. Hypobromous acid may be produced by reacting a bromide such as sodium bromide with a chlorine-based oxidizing agent such as hypochlorous acid.

  Among these, the preparation of “bromine and sulfamic acid compound (mixture of bromine and sulfamic acid compound)” or “reaction product of bromine and sulfamic acid compound” using bromine is composed of “hypochlorous acid and bromine compound and Compared with the preparation of “sulfamic acid” and the preparation of “bromine chloride and sulfamic acid”, etc., since there is less by-product of bromic acid and the reverse osmosis membrane is not further deteriorated, it is more preferable as a fungicide for reverse osmosis membrane.

  That is, in the water treatment method and water treatment apparatus using the reverse osmosis membrane according to the embodiment of the present invention, bromine and a sulfamic acid compound are present in the water to be treated containing ammonia (mixture of bromine and sulfamic acid compound). Is preferably present). Moreover, it is preferable to make the reaction product of a bromine and a sulfamic acid compound exist in the to-be-processed water containing ammonia.

  Examples of bromine compounds include sodium bromide, potassium bromide, lithium bromide, ammonium bromide and hydrobromic acid. Of these, sodium bromide is preferable from the viewpoint of formulation cost and the like.

  Examples of the chlorine-based oxidizing agent include chlorine gas, chlorine dioxide, hypochlorous acid or a salt thereof, chlorous acid or a salt thereof, chloric acid or a salt thereof, perchloric acid or a salt thereof, chlorinated isocyanuric acid or a salt thereof. Etc. Among these, examples of the salt include alkali metal hypochlorites such as sodium hypochlorite and potassium hypochlorite, alkaline earth hypochlorite such as calcium hypochlorite and barium hypochlorite. Metal salts, alkali metal chlorites such as sodium chlorite and potassium chlorite, alkaline earth metal chlorites such as barium chlorite, and other metal chlorites such as nickel chlorite , Alkali metal chlorates such as ammonium chlorate, sodium chlorate and potassium chlorate, and alkaline earth metal chlorates such as calcium chlorate and barium chlorate. These chlorine-based oxidants may be used alone or in combination of two or more. As the chlorine-based oxidant, sodium hypochlorite is preferably used from the viewpoint of handleability.

The sulfamic acid compound is a compound represented by the following general formula (1).
R ₂ NSO ₃ H (1)
(In the formula, R is independently a hydrogen atom or an alkyl group having 1 to 8 carbon atoms.)

  Examples of the sulfamic acid compound include sulfamic acid (amidosulfuric acid) in which both two R groups are hydrogen atoms, N-methylsulfamic acid, N-ethylsulfamic acid, N-propylsulfamic acid, N- A sulfamic acid compound in which one of two R groups such as isopropylsulfamic acid and N-butylsulfamic acid is a hydrogen atom and the other is an alkyl group having 1 to 8 carbon atoms, N, N-dimethylsulfamic acid, N, Two R groups such as N-diethylsulfamic acid, N, N-dipropylsulfamic acid, N, N-dibutylsulfamic acid, N-methyl-N-ethylsulfamic acid, N-methyl-N-propylsulfamic acid, etc. One of two R groups such as a sulfamic acid compound and N-phenylsulfamic acid, both of which are alkyl groups having 1 to 8 carbon atoms, An atom, the other is sulfamic acid compound or a salt thereof, such as an aryl group having 6 to 10 carbon atoms. Examples of the sulfamate include alkali metal salts such as sodium salt and potassium salt, alkaline earth metal salts such as calcium salt, strontium salt and barium salt, manganese salt, copper salt, zinc salt, iron salt, cobalt salt, Other metal salts such as nickel salts, ammonium salts, guanidine salts and the like can be mentioned. The sulfamic acid compounds and salts thereof may be used alone or in combination of two or more. As the sulfamic acid compound, sulfamic acid (amidosulfuric acid) is preferably used from the viewpoint of environmental load.

  In the water treatment method and the water treatment apparatus using the reverse osmosis membrane according to the present embodiment, alkali may be further present in the water to be treated. Examples of the alkali include alkali hydroxides such as sodium hydroxide and potassium hydroxide. Sodium hydroxide and potassium hydroxide may be used in combination from the viewpoint of product stability at low temperatures. Further, the alkali is not solid and may be used as an aqueous solution.

  The water treatment method and water treatment apparatus using the reverse osmosis membrane according to the present embodiment can be suitably applied to polyamide polymer membranes that are currently mainstream as reverse osmosis membranes. Polyamide polymer membranes have a relatively low resistance to oxidizing agents, and when free chlorine or the like is continuously brought into contact with the polyamide polymer membrane, the membrane performance is significantly reduced. However, in the water treatment method and the water treatment apparatus using the reverse osmosis membrane according to this embodiment, such a remarkable membrane performance deterioration hardly occurs even in the polyamide polymer membrane.

  Reverse osmosis membranes include neutral membranes, anion charged membranes, and cation charged membranes. In the present specification, a membrane having a zeta potential at pH 7.0 of −10 mV or more and less than 5 mV determined by the method for measuring a zeta potential described in Examples described later is a neutral membrane, and a membrane having a zeta potential of 5 mV or more is a cation charged membrane. , A membrane of less than −10 mV is defined as an anion charged membrane. The zeta potential of the neutral membrane is preferably −5 mV or more, more preferably −3.9 mV or more, and even more preferably −1.3 mV or more. The upper limit of the zeta potential of the cationic charged membrane is not particularly limited, but is, for example, 20 mV or less.

  In the water treatment method using a reverse osmosis membrane according to the present embodiment, an anion charged membrane is preferably used by using a neutral membrane or a cation charged membrane, more preferably a neutral membrane as reverse osmosis. Compared with the case, the permeation | transmission of the reverse osmosis membrane of the disinfectant containing a bromine type oxidizing agent and a sulfamic acid compound can be suppressed.

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

  Examples of commercially available cationic charged membranes include ES10C (manufactured by Nitto Denko Corporation).

  Examples of commercially available anion charged membranes include ES15, ES20, CPA3, CPA5 (manufactured by Nitto Denko Corporation), RE-8040BLN (manufactured by Eunjin Co., Ltd.), and the like.

  In the water treatment method and the water treatment apparatus using the reverse osmosis membrane according to the present embodiment, the pH of the water to be treated supplied to the reverse osmosis membrane treatment apparatus including the reverse osmosis membrane is preferably 5.5 or more. Is more preferably 0.0 or more, and further preferably 6.5 or more. If the pH of the water to be treated is less than 5.5, the amount of permeated water may decrease. In addition, the upper limit of the pH of the water to be treated is not particularly limited as long as it is equal to or lower than the application upper limit pH of a normal reverse osmosis membrane (for example, pH 10), but considering the scale precipitation of hardness components such as calcium, the pH Is preferably operated at, for example, 9.0 or less. In the case of using the water treatment method and the water treatment apparatus using the reverse osmosis membrane according to the present embodiment, the degradation of the reverse osmosis membrane and the treated water (permeated water) are caused by operating at a pH of the treated water of 5.5 or more. It is possible to secure a sufficient amount of permeated water while suppressing deterioration of water quality and exhibiting a sufficient slime suppressing effect.

  In a reverse osmosis membrane treatment apparatus, when scale is generated at a pH of 5.5 or higher, water may be used in combination with the above bactericide to suppress scale. Examples of the dispersant include polyacrylic acid, polymaleic acid, and phosphonic acid. The amount of the dispersant 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 addition, in order to suppress the occurrence of scale without using a dispersant, for example, reverse osmosis is performed so that the silica concentration in RO concentrated water is less than the solubility and the Langeria index, which is a calcium scale index, is less than 0. Adjusting the operating conditions such as the recovery rate of the membrane processing apparatus can be mentioned.

  Examples of the use of the reverse osmosis membrane treatment apparatus include pure water production, seawater desalination, wastewater recovery, and the like.

  The water treatment method and the water treatment apparatus using the reverse osmosis membrane according to the present embodiment are particularly applied to wastewater recovery, such as electronic industrial wastewater, food production wastewater, drinking water production wastewater, chemical factory wastewater, plating factory wastewater, etc. Can be applied to the recovery of In particular, the recovered water of the electronic industrial wastewater often contains ammonia, and as a flow for recovering the wastewater, for example, the latter stage of the biological treatment system 56 including the biological treatment device 50 and the membrane treatment device 54 as shown in FIG. Moreover, the flow which has the water treatment apparatus 1 and 3 provided with the reverse osmosis membrane processing apparatus 12 to which the water treatment method using the reverse osmosis membrane which concerns on this embodiment is applied can be considered.

  The water treatment system 5 shown in FIG. 3 includes a biological treatment device 50, a biological treatment water tank 52 as a biological treatment means, a membrane treatment device 54 as a membrane treatment means, a membrane treatment water tank 58, and the water treatment devices 1 and 3 described above. Is provided. The water treatment system 5 may include a second reverse osmosis membrane treatment device 60 as the second reverse osmosis membrane treatment means.

  In the water treatment system 5, for example, electronic industrial wastewater is fed as raw water to the biological treatment device 50, and biological treatment is performed in the biological treatment device 50 (biological treatment step). Biologically treated biologically treated water is stored in the biologically treated water tank 52 as necessary, and then sent to the membrane treatment device 54 where membrane treatment (turbidity) is performed by the turbidity membrane. (Membrane treatment step). The membrane-treated water that has been subjected to membrane treatment is stored in the membrane-treated water tank 58 as necessary, and is then sent to the treated water tank 10 of the water treatment devices 1 and 3 as the treated water as needed and stored. . For example, a bactericide containing a bromine-based oxidant and a sulfamic acid compound is added to the water to be treated in the water tank 10 to be treated, the water pipe 14 to be treated or the water supply pipe 16 to be treated, so that the bactericide exists. Addition step). At this time, the sulfamic acid compound is present so that the molar concentration of bromine in the disinfectant is 1.11 times or more.

  The bactericide-containing water in which the bactericide is present is supplied to the reverse osmosis membrane treatment device 12, and the reverse osmosis membrane treatment device 12 performs the reverse osmosis membrane treatment (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 out of the system. The concentrated water may be discharged out of the system, or may be sent to the second reverse osmosis membrane treatment device 60 as necessary, and further the reverse osmosis membrane treatment may be performed in the second reverse osmosis membrane treatment device 60. (Second reverse osmosis membrane treatment step). The concentrated water obtained by the second reverse osmosis membrane treatment is discharged out of the system. The permeated water may be discharged out of the system, or may be sent to the treated water tank 10 and circulated as necessary.

  In the water treatment system 5 of FIG. 3, the biological treatment system 56 including the biological treatment device 50, the biological treatment water tank 52, and the membrane treatment device 54 is illustrated as an example, but the membrane separation activated sludge device ( MBR) may be used.

  In the water treatment system 5 of FIG. 3, the low-molecular-weight organic substance etc. which are contained in raw | natural water are decomposed | disassembled by biological treatment, a biological metabolite etc. are blocked | prevented with the membrane treatment apparatus 54 provided with a turbidity membrane etc. In step 12, various ions and remaining organic substances are blocked to obtain treated water (permeated water). In such wastewater recovery, ammonia is often contained in the wastewater itself, or ammonia is often generated by biological treatment. For example, when wastewater containing tetramethylammonium hydroxide as an organic substance is biologically treated, ammonia is likely to be generated.

  At this time, biofouling of the reverse osmosis membrane in the latter stage is a concern due to biological metabolites generated by biological treatment and low molecular weight organic matter remaining after biological treatment. Although it is conceivable to use hypochlorous acid having a high sterilizing power, hypochlorous acid may deteriorate a polyamide-based reverse osmosis membrane which has become the mainstream in recent years. It is conceivable to provide an activated carbon tower or a reducing agent pouring point in front of the reverse osmosis membrane, but both have problems in terms of initial running cost. Therefore, in the water treatment system 5, the disinfection agent containing bromine-based oxidant and sulfamic acid compound is present in the water to be treated containing ammonia, so that the sterilization ability is high and the polyamide-based reverse osmosis membrane is oxidized and deteriorated. It is effective because it has a high rejection rate at the reverse osmosis membrane and has little influence on the quality of the treated water (permeated water) in the subsequent stage.

  When the bactericidal agent is added in this way, if the bactericidal agent permeates the treated water side, deterioration of the treated water becomes a problem. Therefore, in the water treatment method and the water treatment apparatus using the reverse osmosis membrane according to the present embodiment, the molar concentration of bromine in the disinfectant is contained in the disinfectant, the water to be treated before the disinfectant is present, or both. By allowing the sulfamic acid compound to be 1.11 times or more, the bactericide is hardly detected in the permeated water, and the permeation of the bactericide through the reverse osmosis membrane 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 12, that is, the operating pH of the reverse osmosis membrane treatment device 12 is 9 or less. On the alkali side exceeding pH 9, the desalination rate of the reverse osmosis membrane may decrease, and the oxidizing power of the bactericide may decrease. If the pH of the water to be treated supplied to the reverse osmosis membrane treatment device 12 is 9 or less, the quality of the RO permeate is kept better, and slime generation is further suppressed.

  In the flow of wastewater recovery like the water treatment system 5, it is common to provide the 2nd reverse osmosis membrane processing apparatus 60 (brine RO) in order to raise a water recovery rate. The second reverse osmosis membrane treatment device 60 uses the concentrated water of the reverse osmosis membrane treatment device 12 as raw water, returns the permeated water to the water tank 10 to be treated, and discharges the concentrated water out of the system. The second reverse osmosis membrane treatment apparatus 60 also has a risk of slime generation, and if the reverse osmosis membrane treatment apparatus 12 has a low disinfectant permeability, the disinfectant component remains in the raw water of the second reverse osmosis membrane treatment apparatus 60. become. Many germicide components remain in the raw water of the second reverse osmosis membrane treatment device 60, and slime generation in the second reverse osmosis membrane treatment device 60 is suppressed.

  In the water treatment system 5 of FIG. 3, the biological treatment is described as an example of the pretreatment of the reverse osmosis membrane treatment. However, in the pretreatment step of the reverse osmosis membrane treatment, the biological treatment, the coagulation treatment, the coagulation sedimentation treatment, and the pressure levitation Biological, physical or chemical pretreatment such as treatment, filtration treatment, membrane separation treatment, activated carbon treatment, ozone treatment, ultraviolet irradiation treatment, and combinations of two or more of these pretreatments as necessary It may be done.

  In the water treatment devices 1 and 3, in addition to the reverse osmosis membrane in the system, a pump, a safety filter, a flow rate measuring device, a pressure measuring device, a temperature measuring device, a redox potential (ORP) measuring device, a residual chlorine measuring device, an electric A conductivity measuring device, a pH measuring device, an energy recovery device, and the like may be provided as necessary.

  In the water treatment system 5, if necessary, a scale inhibitor other than the stabilized hypobromite composition or a pH adjuster is added to the biological treatment water tank 52 and the pipes before and after the biological treatment water tank 58 and the pipes before and after the membrane treatment water tank 58. In at least one of the water tank 10 and the pipes before and after the water tank 10, the water may be added to at least one of the biologically treated water, the membrane treated water, and the treated water.

<Fungicide>
The disinfectant according to the present embodiment contains a stabilized hypobromite composition containing a mixture of a “bromine-based oxidizing agent” and a “sulfamic acid compound”, and may further contain an alkali.

  Moreover, the disinfectant according to the present embodiment contains a stabilized hypobromite composition containing “a reaction product of a bromine-based oxidant and a sulfamic acid compound”, and further contains an alkali. Good.

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

  As the disinfectant according to the present embodiment, in order not to further deteriorate the reverse osmosis membrane, one containing bromine and a sulfamic acid compound (containing a mixture of bromine and sulfamic acid compound), for example, bromine and sulfamic acid A mixture of a compound, an alkali and water, or a reaction product containing a reaction product of bromine and a sulfamic acid compound, for example, a reaction product of bromine and a sulfamic acid compound, and a mixture of an alkali and water is preferable.

  Among the bactericides according to the present embodiment, a bactericide containing a stabilized hypobromite composition containing bromine and a sulfamic acid compound in particular is a bactericidal agent containing chlorinated oxidant and sulfamic acid compound (chlorosulfamine). Compared with acid, etc.), although the oxidizing power is high and the slime inhibiting power and the slime peeling power are remarkably high, the film hardly causes remarkable film deterioration like hypochlorous acid having a high oxidizing power. At normal use concentrations, the effect on film degradation can be substantially ignored. For this reason, it is optimal as a disinfectant.

  Unlike hypochlorous acid, the disinfectant according to the present embodiment hardly permeates the reverse osmosis membrane, and therefore has little influence on the quality of treated water. Further, since the concentration can be measured on site in the same manner as hypochlorous acid or the like, more accurate concentration management is possible.

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

  The bromic acid concentration in the disinfectant is preferably less than 5 mg / kg. If the bromate concentration in the bactericide is 5 mg / kg or more, the concentration of bromate ions in the RO permeate may increase.

<Manufacturing method of disinfectant>
The disinfectant according to the present embodiment is obtained by mixing a bromine-based oxidizing agent and a sulfamic acid compound, and may further be mixed with an alkali.

  As a method for producing a disinfectant containing a stabilized hypobromite composition containing bromine and a sulfamic acid compound, bromine is added to a mixed liquid containing water, an alkali and a sulfamic acid compound in an inert gas atmosphere. It is preferable to include a step of reacting or adding bromine to a mixed solution containing water, an alkali and a sulfamic acid compound in an inert gas atmosphere. By adding and reacting under an inert gas atmosphere or adding under an inert gas atmosphere, the bromate ion concentration in the disinfectant is lowered, and the bromate 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 viewpoint of manufacturing and the like, and nitrogen is particularly preferable from the viewpoint of manufacturing cost and the like.

  The oxygen concentration in the reactor upon addition of bromine is preferably 6% or less, more preferably 4% or less, further preferably 2% or less, and particularly preferably 1% or less. If the oxygen concentration in the reactor during the bromine reaction exceeds 6%, the amount of bromic acid produced in the reaction system may increase.

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

  The reaction temperature during the addition of bromine is preferably controlled in the range of 0 ° C. to 25 ° C., but more preferably in the range of 0 ° C. to 15 ° C. from the viewpoint of production cost and the like. When the reaction temperature at the time of bromine addition exceeds 25 degreeC, the production amount of the bromic acid in a reaction system may increase, and when it is less than 0 degreeC, it may freeze.

  Hereinafter, although an example and a comparative example are given and the present invention is explained more concretely in detail, the present invention is not limited to the following examples.

[Preparation of Stabilized Hypobromite Composition (Composition 1)]
Under nitrogen atmosphere, liquid bromine: 16.9% by weight (wt%), sulfamic acid: 10.7% by weight, sodium hydroxide: 12.9% by weight, potassium hydroxide: 3.94% by weight, water: remaining The components were mixed to prepare a stabilized hypobromite composition (Composition 1). The stabilized hypobromite composition had a pH of 14 and a total chlorine concentration of 7.5% by weight. The total chlorine concentration is a value (mg / L asCl ₂ ) measured by a total chlorine measurement method (DPD (diethyl-p-phenylenediamine) method) using a multi-item water quality analyzer DR / 4000 manufactured by HACH. The detailed method for preparing the stabilized hypobromite composition is as follows.

  Add 1436 g of water and 361 g of sodium hydroxide to a 2 L four-necked flask sealed by continuous injection while controlling the flow rate of nitrogen gas with a mass flow controller so that the oxygen concentration in the reaction vessel is maintained at 1%. Next, after adding 300 g of sulfamic acid and mixing, 473 g of liquid bromine was added while maintaining cooling so that the temperature of the reaction solution was 0 to 15 ° C., and 230 g of 48% potassium hydroxide solution was added. The desired stabilized hypobromite composition, wherein the sulfamic acid is 10.7% by weight relative to the total amount of the composition, 16.9% bromine, and the equivalent ratio of sulfamic acid to the equivalent of bromine is 1.04. Composition 1) was obtained. The pH of the resulting solution was 14 as measured by the glass electrode method. The bromine content of the resulting solution was 16.9% as measured by a redox titration method using sodium thiosulfate after bromine was converted to iodine with potassium iodide, and the theoretical content (16.9% ) Of 100.0%. In addition, the oxygen concentration in the reaction vessel during the bromine reaction was measured using “Oxygen Monitor JKO-02 LJDII” manufactured by Zico Corporation. The bromic acid concentration 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 Toa DKK Corporation Electrode calibration: Neutral phosphate pH (6.86) standard solution (type 2) manufactured by Kanto Chemical Co., boric acid manufactured by the same company Salt temperature (9.18) Standard solution (type 2) was measured by two-point calibration Measurement temperature: 25 ° C
Measurement value: Immerse the electrode in the measurement solution and use the value after stabilization as the measurement value.

[Measurement of zeta potential of reverse osmosis membrane]
The zeta potential of the reverse osmosis membrane was determined using a zeta potential / particle size measurement system ELSZseries manufactured by Otsuka Electronics Co., Ltd. The zeta potential of the reverse osmosis membrane was calculated based on the measured electroosmosis plot from the following Mori-Okamoto equation and Smoluchowski equation.

(Mori / Okamoto formula)
U _obs (z) = AU ₀ (z / b) ² + ΔU ₀ (z / b) + (1−A) U ₀ + U _p
here,
z: Distance from the cell center position U _obs (z): Apparent mobility at the z position in the cell A: 1 / [(2/3) − (0.420166 / K)]
K = a / b: 2a and 2b are the horizontal and vertical lengths of the cell cross section, 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 between the upper and lower surfaces of the cell (Smoluchowski equation)
ζ = 4πηU / ε
here,
U: Electric mobility ε: Dielectric constant of solvent η: Viscosity of solvent

  A 10 mM NaCl aqueous solution (pH about 5.4) was used as a measurement solution. Two pairs of this aqueous solution and sample are prepared for each sample, one is adjusted to acidic (pH 2, 3, 4, 5, 6, 7) and the other is adjusted to alkaline (pH 8, 9), The zeta potential at each pH was measured. As the physical properties of the solvent, pure water values (refractive index: 1.3328, viscosity: 0.8878, dielectric constant: 78.3) at 25 ° C. were used.

<Examples 1-6>
[Test conditions and test methods]
The transmittance of the bactericide was measured by a flat membrane test. As the flat membrane cell, a membrane master C70-F flow type flat membrane test cell manufactured by Nitto Denko Corporation was used. As the flat membrane, a reverse osmosis membrane ES15 manufactured by Nitto Denko Corporation was used. Nitto Denko's ES15 is an anion charged membrane (zeta potential: -35 mV). The flat membrane was circular and had a diameter of 75 mm. The flow is shown in FIG.

The test water (treated water) for the flat membrane test was prepared by dissolving 500 mg / L sodium chloride in pure water and adding ammonium chloride so that the ammonia concentration was 10 mg / L. Depending on the test conditions, sodium sulfamate was added to the water to be treated to adjust the concentration of sulfamic acid, and the pH was adjusted to 6.5 with hydrochloric acid or sodium hydroxide. The concentration of the disinfectant was added so that the total chlorine concentration was about 5 to 12 mg / L. The water temperature was adjusted using a chiller so as to be 25 ± 1 ° C. The operating pressure of the reverse osmosis membrane was 0.75 MPa. The water supplied to the reverse osmosis membrane was passed at 5 L / min. Sampling was performed within 10 minutes after the start of water flow, and the disinfectant concentration (total chlorine concentration) of the water to be treated and the permeated water was measured to determine the disinfectant permeability. The total chlorine concentration is a value (mg / L asCl ₂ ) measured by a total chlorine measurement method (DPD (diethyl-p-phenylenediamine) method) using a multi-item water quality analyzer DR / 4000 manufactured by HACH.

  The above test was conducted by changing the molar ratio of sulfamic acid to bromine (sulfamic acid / bromine) from 1.11 to 9.40 as shown in Table 1. The results are shown in FIG.

<Comparative Example 1>
As Comparative Example 1, the above test was carried out with a sulfamic acid / bromine molar ratio of 1.04. The results are shown in FIG.

  It was found that the higher the molar ratio of sulfamic acid to bromine (sulfamic acid / bromine), the lower the germicide permeability. When the molar ratio of sulfamic acid to bromine (sulfamic acid / bromine) exceeds 1.57, the effect of decreasing the germicide permeability due to the increase in sulfamic acid becomes gradual, which is disadvantageous from the viewpoint of increasing the cost due to the addition of sulfamic acid. It is considered to be.

  Thus, in the water treatment method and the water treatment apparatus for treating the water to be treated containing ammonia with the reverse osmosis membrane according to the method of the embodiment, in the reverse osmosis membrane of the bactericide containing the bromine-based oxidant and the sulfamic acid compound Transmission could be suppressed.

  1,3 water treatment apparatus, 5 water treatment system, 10 treated water tank, 12 reverse osmosis membrane treatment apparatus, 14 treated water pipe, 16 treated water supply pipe, 18 permeated water pipe, 20 concentrated water pipe, 22 disinfectant Addition piping, 50 biological treatment device, 52 biological treatment water tank, 54 membrane treatment device, 56 biological treatment system, 58 membrane treatment water tank, 60 second reverse osmosis membrane treatment device.

Claims (10)

A method for treating water containing ammonia with a reverse osmosis membrane, a water treatment method using a reverse osmosis membrane,
In the treated water, a disinfectant containing a bromine-based oxidizing agent and a sulfamic acid compound is present,
In the disinfectant, the sulfamic acid compound is present in the treated water before the disinfectant is present, or both so that the molar concentration of bromine in the disinfectant is 1.11 times or more. A water treatment method using a reverse osmosis membrane. A method for treating water containing ammonia with a reverse osmosis membrane, a water treatment method using a reverse osmosis membrane,
In the treated water, a disinfectant containing bromine and a sulfamic acid compound is present,
In the disinfectant, the sulfamic acid compound is present in the treated water before the disinfectant is present, or both so that the molar concentration of bromine in the disinfectant is 1.11 times or more. A water treatment method using a reverse osmosis membrane. A water treatment method using the reverse osmosis membrane according to claim 1 or 2,
In the disinfectant, the sulfamic acid compound is present in the water to be treated before the disinfectant is present, or both, so that the molar concentration of bromine in the disinfectant is 1.57 times or less. A water treatment method using a reverse osmosis membrane. A water treatment method using the reverse osmosis membrane according to any one of claims 1 to 3,
A water treatment method using a reverse osmosis membrane, wherein the water to be treated is treated with the reverse osmosis membrane immediately after the disinfectant is present in the water to be treated. A water treatment method using the reverse osmosis membrane according to any one of claims 1 to 4,
The treatment water is treated with the reverse osmosis membrane immediately after adding the bactericide to the pipe for passing the treatment water through the reverse osmosis membrane in a line, A water treatment method using a reverse osmosis membrane. A water treatment apparatus using a reverse osmosis membrane for treating water to be treated containing ammonia with a reverse osmosis membrane,
In the treated water, a disinfectant containing a bromine-based oxidizing agent and a sulfamic acid compound is present,
In the disinfectant, the sulfamic acid compound is present in the treated water before the disinfectant is present, or both so that the molar concentration of bromine in the disinfectant is 1.11 times or more. A water treatment apparatus using a reverse osmosis membrane. A water treatment apparatus using a reverse osmosis membrane for treating water to be treated containing ammonia with a reverse osmosis membrane,
In the treated water, a disinfectant containing bromine and a sulfamic acid compound is present,
In the disinfectant, the sulfamic acid compound is present in the treated water before the disinfectant is present, or both so that the molar concentration of bromine in the disinfectant is 1.11 times or more. A water treatment apparatus using a reverse osmosis membrane. A water treatment apparatus using the reverse osmosis membrane according to claim 6 or 7,
In the disinfectant, the sulfamic acid compound is present in the water to be treated before the disinfectant is present, or both, so that the molar concentration of bromine in the disinfectant is 1.57 times or less. A water treatment apparatus using a reverse osmosis membrane. A water treatment apparatus using the reverse osmosis membrane according to any one of claims 6 to 8,
A water treatment apparatus using a reverse osmosis membrane, wherein the water to be treated is treated with the reverse osmosis membrane immediately after the disinfectant is present in the water to be treated. A water treatment apparatus using the reverse osmosis membrane according to any one of claims 6 to 9,
The treatment water is treated with the reverse osmosis membrane immediately after adding the bactericide to the pipe for passing the treatment water through the reverse osmosis membrane in a line, Water treatment device using reverse osmosis membrane.