JP6085155B2 - Ammonia-containing wastewater treatment apparatus and ammonia-containing wastewater treatment method - Google Patents

Description

  The present invention relates to a treatment apparatus and treatment method for ammonia-containing wastewater containing ammonia, and more particularly to a treatment apparatus and treatment method for ammonia-containing wastewater containing ammonia at a high concentration.

  As a method for treating ammonia-containing wastewater containing ammonia, a method combining ammonia stripping treatment for evaporating ammoniacal nitrogen as ammonia gas and reverse osmosis membrane treatment is known.

  For example, Patent Document 1 discloses a method in which after adding a scale dispersant to concentrated water separated by reverse osmosis membrane treatment of ammonia-containing wastewater, ammonia stripping treatment is performed at a pH of 10 or more, and the extracted ammonia gas is decomposed. The reverse osmosis membrane treatment process includes a primary reverse osmosis membrane treatment step in which ammonia-containing wastewater is treated with a reverse osmosis membrane to separate it into primary permeate and primary concentrated water, and the primary permeate is subjected to reverse osmosis membrane treatment and secondary permeation A secondary reverse osmosis membrane treatment step for separating water and secondary concentrated water; and a primary concentrated water reverse osmosis membrane treatment step for separating the primary concentrated water into reverse osmosis membrane and separating it into permeated water and concentrated water. A method for treating ammonia-containing wastewater is described in which concentrated water is subjected to ammonia stripping treatment, while secondary concentrated water and permeated water are sent to the previous stage of the primary reverse osmosis membrane treatment step.

  However, the method as disclosed in Patent Document 1 has a problem that the chemical cost of the scale dispersant is high, and it is difficult to optimize the amount of the chemical added due to water quality fluctuations in the ammonia-containing wastewater.

  On the other hand, there is a method of treating the ammonia-containing wastewater with a reverse osmosis membrane after performing an ammonia stripping treatment at a pH of 10 or higher.

  When wastewater containing high-concentration ammonia containing high-concentration ammonia (for example, ammonia concentration of 500 mg / L or more) is treated by this method, it is difficult to completely remove ammonia by ammonia stripping treatment. A few tens mg / L (for example, about 20 mg / L) of ammonia may remain in water.

  If the ammonia stripping treatment water in which ammonia remains is adjusted to a pH of 7 or less and then subjected to reverse osmosis membrane treatment, the permeated water becomes high-purity water from which ammonia, other ionic components, organic substances, etc. are eliminated, and pure water production It can be reused for miscellaneous water such as equipment and cooling water.

  However, since concentrated ammonia, other ionic components, organic substances, and the like are concentrated in the concentrated water of the reverse osmosis membrane treatment, a waste water treatment for further removing ammonia is necessary so that the ammonia concentration is below the waste water standard.

  In order to avoid further wastewater treatment to remove this ammonia, it is conceivable to treat the ammonia by circulating the concentrated water of the reverse osmosis membrane treatment to the upstream side of the ammonia stripping treatment. Organic substances are also concentrated and circulated by reverse osmosis membrane treatment, and in ammonia distillation stripping towers and reverse osmosis membranes, ionic components are scaled and slime contamination due to organic matter occurs, resulting in reduced processing performance. There is.

  In order to solve this problem, there is a method for suppressing scaling of ionic components and slime contamination by organic substances by adding a scale dispersant or adding a slime control agent or the like to the system as in the method of Patent Document 1. However, there is still a cost for chemicals such as scale dispersion, and it is difficult to optimize the amount of chemicals added due to fluctuations in the water quality of ammonia-containing wastewater, and the treatment of organic substances contained in scale dispersants and slime control agents is difficult. There is a problem that it becomes necessary newly.

Japanese Patent No. 3667597

  An object of the present invention is to provide an ammonia-containing wastewater treatment apparatus and an ammonia-containing wastewater that can be efficiently treated even with high-concentration ammonia-containing wastewater without using chemicals such as scale dispersants and slime control agents. It is to provide a method for treating waste water.

The present invention relates to a hydrogen peroxide decomposition means for decomposing hydrogen peroxide in ammonia-containing wastewater containing ammonia and hydrogen peroxide, and an ammonia stroking treatment for ammonia-stripping treatment of ammonia-containing wastewater from which hydrogen peroxide has been decomposed at a pH of 10 or more. A primary reverse osmosis membrane treatment in which a first reverse osmosis membrane treatment is performed at a pH of 10 or higher on the ammonia stripping treatment water subjected to the ammonia stripping treatment and separated into primary permeated water and primary concentrated water. Means, a secondary reverse osmosis membrane treatment means for subjecting the primary permeate to a second-stage reverse osmosis membrane treatment at a pH of 8.5 or less and separating the secondary permeate into secondary permeate and secondary concentrated water, and the secondary An ammonia-containing wastewater treatment apparatus comprising: the hydrogen peroxide decomposition means or a circulation means for circulating the concentrated water to the upstream side of the hydrogen peroxide decomposition means .

  In the ammonia-containing wastewater treatment apparatus, the hydrogen peroxide decomposition means preferably decomposes hydrogen peroxide by an enzyme treatment using catalase.

The present invention also provides a hydrogen peroxide decomposition step for decomposing hydrogen peroxide in ammonia-containing wastewater containing ammonia and hydrogen peroxide, and ammonia-stripping treatment of the ammonia-containing wastewater from which hydrogen peroxide has been decomposed at a pH of 10 or more. Ammonia stripping treatment step, and the ammonia stripping treated water subjected to the ammonia stripping treatment is subjected to a first-stage reverse osmosis membrane treatment at a pH of 10 or more to separate into primary permeated water and primary concentrated water. A membrane treatment step, a secondary reverse osmosis membrane treatment step of performing a second-stage reverse osmosis membrane treatment of the primary permeate water at a pH of 8.5 or less, and separating it into a secondary permeate water and a secondary concentrated water; And a circulating step of circulating secondary concentrated water to the hydrogen peroxide decomposition step or to the upstream side of the hydrogen peroxide decomposition step .

  In the ammonia-containing wastewater treatment method, it is preferable that hydrogen peroxide is decomposed by an enzyme treatment using catalase in the hydrogen peroxide decomposition step.

  In the present invention, the ammonia-containing wastewater is subjected to ammonia stripping treatment at a pH of 10 or more, then the ammonia stripping treatment water is subjected to a first-stage reverse osmosis membrane treatment at a pH of 10 or more, and the primary permeated water is treated in two steps at a pH of 8.5 or less. Reverse osmosis membrane treatment of eyes and circulating secondary concentrated water to the upstream side of ammonia stripping treatment means, so that high concentration of ammonia is contained without using chemicals such as scale dispersant and slime control agent Even wastewater can be treated efficiently.

It is a schematic block diagram which shows an example of the ammonia containing waste water treatment equipment which concerns on embodiment of this invention. It is a schematic block diagram which shows the other example of the ammonia containing waste water treatment equipment which concerns on embodiment of this invention. It is a schematic block diagram which shows the other example of the ammonia containing waste water treatment equipment which concerns on embodiment of this invention. It is a schematic block diagram which shows the other example of the ammonia containing waste water treatment equipment which concerns on embodiment of this invention. It is a schematic block diagram which shows the ammonia containing waste water treatment equipment used in Example 1. FIG. It is a schematic block diagram which shows the ammonia containing waste water treatment equipment used in the comparative example 1. It is a figure which shows the relationship between pH, the fraction of ammonia, and the fraction of ammonium ion.

  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.

  The outline of an example of the processing apparatus of the ammonia containing waste_water | drain based on embodiment of this invention is shown in FIG. 1, and the structure is demonstrated. The ammonia-containing wastewater treatment apparatus 1 includes a raw water tank 10, an ammonia stripping treatment apparatus 12 as an ammonia stripping treatment means, a primary reverse osmosis membrane treatment apparatus 14 as a primary reverse osmosis membrane treatment means, and a secondary reverse A secondary reverse osmosis membrane treatment device 16 as osmosis membrane treatment means.

  1, the raw water pipe 18 is connected to the inlet of the raw water tank 10, and the outlet of the raw water tank 10 and the inlet of the ammonia stripping treatment apparatus 12 are connected by the raw water pipe 20, The ammonia stripping treatment water outlet of the ripping treatment device 12 and the inlet of the primary reverse osmosis membrane treatment device 14 are connected by an ammonia stripping treatment water pipe 22, and the primary permeate outlet of the primary reverse osmosis membrane treatment device 14 The inlet of the secondary reverse osmosis membrane treatment apparatus 16 is connected by a primary permeate water pipe 24, and the treated water pipe 26 is connected to the secondary permeate outlet of the secondary reverse osmosis membrane treatment apparatus 16. An ammonia gas pipe 30 is connected to the ammonia gas outlet of the ammonia stripping treatment apparatus 12, and a primary concentrated water pipe 32 is connected to the primary concentrated water outlet of the primary reverse osmosis membrane treatment apparatus 14, and the secondary reverse The secondary concentrated water outlet of the osmosis membrane treatment device 16 and the raw water tank 10 are connected to a secondary concentrated water circulation pipe 28 as a circulation means.

  The operation of the ammonia-containing wastewater treatment method and the ammonia-containing wastewater treatment apparatus 1 according to this embodiment will be described.

Ammonia-containing wastewater that is raw water (for example, high-concentration ammonia-containing wastewater having an ammonia concentration of 500 mg / L or more) is sent to the raw water tank 10 through the raw water pipe 18 and stored. In the raw water tank 10, an alkaline agent is added to the ammonia-containing wastewater, and the pH is adjusted to 10 or more (first pH adjustment step). If the pH of the ammonia-containing wastewater is already pH 10 or higher, this pH adjustment need not be performed. By adjusting the pH of the ammonia-containing wastewater to 10 or more, most of the ammonia in the ammonia-containing wastewater becomes free ammonia (NH ₃ ). The alkaline agent may be added in the raw water tank 10 or may be added in a line in the raw water pipe 20.

  The ammonia-containing wastewater adjusted to pH 10 or higher is sent to the ammonia stripping treatment device 12 through the raw water pipe 20, and is subjected to ammonia stripping treatment at pH 10 or higher in the ammonia stripping treatment device 12 (ammonia stripping treatment step).

  The ammonia stripping treatment apparatus 12 is, for example, a device in which a perforated plate, a packing, or the like is installed inside a distillation column, and ammonia-containing wastewater that is water to be treated flows from the top of the distillation column, and steam flows from the bottom. When the water to be treated is brought into contact with the steam, free ammonia in the ammonia-containing waste water is expelled to the steam side.

  The discharged ammonia gas is sent to the ammonia gas decomposition treatment device through the ammonia gas pipe 30 and decomposed (ammonia gas decomposition treatment step). This ammonia gas decomposition treatment includes, for example, a method of decomposing into harmless nitrogen through a catalyst reaction tower packed with a catalyst, a method of reacting with sulfuric acid to make ammonium sulfate, etc., which can be recovered and reused as ammonia water. is there.

The ammonia stripping treated water subjected to the ammonia stripping treatment is sent to the primary reverse osmosis membrane treatment device 14 through the ammonia stripping treatment water pipe 22. Since the ammonia stripping treated water has its pH lowered due to the removal of most of the ammonia, an alkaline agent is added to the ammonia stripping treated water pipe 22 to adjust the pH to 10 or more (second pH adjusting step). . By adjusting the pH of the ammonia stripping treated water to 10 or more, most of the ammonia remaining in the ammonia stripping treated water becomes free ammonia (NH ₃ ). The alkali agent may be added in the ammonia stripping treatment water pipe 22 or added in the relay tank by providing a relay tank between the ammonia stripping treatment apparatus 12 and the primary reverse osmosis membrane treatment apparatus 14. May be. Further, a filtration device such as a microfiltration device may be provided between the relay tank and the primary reverse osmosis membrane treatment device 14 in order to protect the subsequent reverse osmosis membrane.

  The ammonia stripping treated water adjusted to pH 10 or higher is subjected to the first-stage reverse osmosis membrane treatment at pH 10 or higher in the primary reverse osmosis membrane treatment device 14 and separated into primary permeated water and primary concentrated water. (Primary reverse osmosis membrane treatment step).

  In the primary reverse osmosis membrane treatment step, the ammonia stripping treated water, which is the treated water, has a pH of 10 or more, and therefore, several tens of mg / L (for example, about 20 mg / L) of ammonia remained. However, since most of it is free ammonia, it is hardly concentrated and most of it remains in the primary permeated water, while other ionic components, organic substances, etc. are excellent in the first-stage reverse osmosis membrane treatment. Concentrated and contained in primary concentrated water.

  The primary concentrated water separated by the first-stage reverse osmosis membrane treatment is discharged through the primary concentrated water pipe 32. This primary concentrated water may be sent to a wastewater treatment apparatus to be subjected to wastewater treatment (a wastewater treatment step). Although it is processed by the waste water treatment to a level equal to or lower than the waste water standard, the primary concentrated water contains almost no ammonia. Therefore, it is not necessary to perform the ammonia removing treatment for removing ammonia.

  Further, in the primary reverse osmosis membrane treatment step, it is difficult for organisms to live on the reverse osmosis membrane by being treated at pH 10 or higher, and slime generation in the reverse osmosis membrane treatment can be suppressed.

The primary permeate separated by the first-stage reverse osmosis membrane treatment is sent to the secondary reverse osmosis membrane treatment device 16 through the primary permeate water pipe 24. Here, an acid is added in the primary permeate pipe 24 to adjust the pH to 8.5 or less (third pH adjustment step). By adjusting the pH of the primary permeate to 8.5 or less, most of the free ammonia contained in the primary permeate becomes ammonium ions (NH ₄ ⁺ ). The acid may be added in the primary permeate pipe 24 or added in the relay tank by providing a relay tank between the primary reverse osmosis membrane treatment device 14 and the secondary reverse osmosis membrane treatment device 16. May be.

  The primary permeated water adjusted to pH 8.5 or lower is subjected to the second-stage reverse osmosis membrane treatment at pH 8.5 or lower in the secondary reverse osmosis membrane treatment device 16, and the secondary permeated water, the secondary concentrated water, (Secondary reverse osmosis membrane treatment step).

  In the secondary reverse osmosis membrane treatment step, the pH of the primary permeated water that is the water to be treated is 8.5 or less, and therefore, for example, about several tens mg / L (for example, 20 mg / L) contained in the primary permeated water. Most of the ammonia is concentrated in the second stage reverse osmosis membrane treatment, and most of it is contained in the secondary concentrated water while the second stage reverse osmosis membrane treatment. The secondary permeated water becomes highly pure water from which ammonia, other ionic components, organic substances, etc. are well eliminated, is discharged through the treated water pipe 26, and is recovered and reused for miscellaneous water such as pure water production equipment and cooling water. Is possible.

  Moreover, in the secondary reverse osmosis membrane treatment step, it is easy to inhabit organisms on the reverse osmosis membrane by treatment at pH 8.5 or lower, but organic substances that are nutrient sources, ion components that cause scaling, etc. Is already eliminated in the first-stage reverse osmosis membrane treatment, so that slime generation and scaling in the reverse osmosis membrane treatment can be suppressed.

  On the other hand, the secondary concentrated water separated by the second-stage reverse osmosis membrane treatment is sent to the raw water tank 10 through the secondary concentrated water circulation pipe 28 and circulated (circulation process).

  The secondary concentrated water separated by the second-stage reverse osmosis membrane treatment contains, for example, several hundred mg / L (for example, about 100 to 200 mg / L) of ammonia. The secondary concentrated water separated by the membrane treatment is circulated to the raw water tank 10 in the previous stage and the ammonia stripping treatment is performed in the ammonia stripping treatment device 12, whereby ammonia can be efficiently removed. The secondary concentrated water may be circulated to the upstream side of the ammonia stripping treatment means, may be circulated to the raw water tank 10, or may be circulated to the raw water pipe 20.

  Thus, in the combination of ammonia stripping treatment and two-stage reverse osmosis membrane treatment with different treatment pH, ionic components and organic substances that cause scaling and slime contamination are removed in the first-stage reverse osmosis membrane. Concentrated and removed by treatment, ammonia is concentrated and circulated in the second-stage reverse osmosis membrane treatment, so that the ionic components can be scaled and organic substances can be added without adding chemicals such as scale dispersants and slime control agents. Slime contamination is suppressed, and ammonia can be efficiently removed even with highly concentrated ammonia-containing wastewater.

  The secondary permeated water separated by the reverse osmosis membrane treatment in the second stage becomes high-purity water from which ammonia, other ionic components, organic substances, and the like are well removed, and is used for various purposes such as pure water production equipment and cooling water. It can be recovered and reused in water.

  In the conventional method, in particular, it is difficult to completely remove ammonia contained in high-concentration ammonia-containing wastewater containing, for example, 500 mg / L or more of ammonia by ammonia stripping treatment, and when ordinary ammonia stripping treatment is performed, In the ammonia stripping-treated water, usually about several tens mg / L of ammonia remains. In the ammonia-containing wastewater treatment method and the ammonia-containing wastewater treatment apparatus according to this embodiment, in the treatment of the high-concentration ammonia-containing wastewater, first, alkali is added, and ammonia is treated by ammonia stripping treatment using a distillation tower or the like. Ammonia remains in the ammonia stripping water without being completely removed. In the first stage reverse osmosis membrane treatment, the residual ammonia is treated at a pH of 10 or more, and most of the residual ammonia is permeated to eliminate ions as scale components, organic substances as slime-causing substances, and the like. In the second-stage reverse osmosis membrane treatment, the first-stage primary permeate is adjusted to pH 8.5 or lower, and then the ammonia is concentrated to circulate to the raw water. In this way, the two-stage reverse osmosis membrane treatment removes ions and organic substances from the circulation system, and ammonia is circulated to suppress scaling and slime generation in the ammonia stripping distillation column and reverse osmosis membrane. It is possible to remove ammonia efficiently.

The pH in the ammonia stripping treatment is 10 or more, preferably 10.5 or more, and more preferably 10.5 to 12. When the pH in the ammonia stripping treatment is less than 10, as shown in FIG. 7, the relationship between the pH obtained from the dissociation constant of ammonia and the ammonia fraction and ammonium ion fraction is shown as free ammonia (NH ₃ ). As a result, the ammonia removal efficiency decreases. If the pH in the ammonia stripping treatment exceeds 12, there may be a problem that the porous plate and the packing inside the distillation column in the ammonia stripping treatment may be deteriorated or the cost of the alkali chemicals is increased. is there.

  Since the ammonia stripping treatment becomes more efficient as the temperature increases, it is preferable to increase the water temperature from 80 ° C. to 100 ° C. by steam. It is also effective in that the ammonia stripping water is thermally sterilized by increasing the water temperature from 80 ° C. to 100 ° C., and slime generation in the subsequent reverse osmosis membrane is suppressed.

The pH in the primary reverse osmosis membrane treatment step is 10 or more, and is preferably 10.5 or more, more preferably 11 or more, in order to increase the fraction of free ammonia. Even if some ammonia is left in the concentrated water, there are few problems as wastewater treatment. Therefore, the pH may be 10 or more from the viewpoint of reducing the amount of alkali added. Moreover, it is preferable that the upper limit of pH is 12 or less. When the pH in the primary reverse osmosis membrane treatment step is less than 10, as shown in FIG. 7, the fraction of free ammonia (NH ₃ ) becomes low, the ammonia is concentrated and the content of ammonia in the primary concentrated water is reduced. To increase. When the pH in the primary reverse osmosis membrane treatment step exceeds 12, the reverse osmosis membrane deteriorates, the amount of alkali added increases, the salt concentration increases and the osmotic pressure increases, and the amount of permeate decreases, the desalting performance There may be a problem such as lowering of the image quality.

The pH in the secondary reverse osmosis membrane treatment step is 8.5 or less, preferably 8 or less, and more preferably 7 or less. The lower limit of pH is preferably 5 or more. When the pH in the secondary reverse osmosis membrane treatment step exceeds 8.5, the ammonium ion (NH ₄ ⁺ ) fraction decreases as shown in FIG. 7, and ammonia permeates to contain ammonia in the secondary permeated water. The amount increases. When the pH in the secondary reverse osmosis membrane treatment step is less than 5, the acid addition amount increases, the salt concentration increases and the osmotic pressure increases, the amount of permeate decreases, and the desalting performance decreases. May occur.

  The temperature in the primary reverse osmosis membrane treatment step and the secondary reverse osmosis membrane treatment step may be, for example, about 30 to 40 ° C.

  The secondary concentrated water may be circulated to the upstream side of the ammonia stripping treatment device 12, and may be circulated to the raw water pipe 18 instead of the raw water tank 10.

  The ammonia-containing wastewater treatment apparatus and the ammonia-containing wastewater treatment method according to the present embodiment are intended to treat ammonia-containing wastewater, and the ammonia concentration is 500 mg / L or more, preferably the ammonia concentration is 1,000 mg / L or more. It is suitably applied to the treatment of wastewater containing high concentration ammonia.

  Examples of other ionic components contained in the ammonia-containing wastewater include calcium ions, magnesium ions, and sulfate ions that cause scaling.

  Examples of the organic substance contained in the ammonia-containing waste water include isopropyl alcohol and tetramethylammonium hydroxide.

  Examples of the alkaline agent used for pH adjustment include alkaline aqueous solutions such as an aqueous sodium hydroxide solution, and examples of the acid include hydrochloric acid and sulfuric acid.

  The ammonia-containing wastewater may contain hydrogen peroxide in addition to ammonia. FIG. 2 and FIG. 3 show a schematic configuration of an example of an ammonia-containing wastewater treatment apparatus suitable for treating ammonia-containing wastewater containing hydrogen peroxide.

  In the ammonia-containing wastewater treatment apparatus 2 in FIG. 2, a catalase addition pipe 34 is connected to the raw water tank 10 in addition to the configuration of the ammonia-containing wastewater treatment apparatus 1 in FIG. 1.

  Ammonia-containing wastewater containing hydrogen peroxide as raw water (for example, high-concentration ammonia-containing wastewater having an ammonia concentration of 500 mg / L or more and a hydrogen peroxide concentration of 1000 mg / L or more) is sent to the raw water tank 10 through the raw water pipe 18. And stored. In the raw water tank 10, an alkaline agent is added to the ammonia-containing wastewater, and the pH is adjusted to 10 or more (first pH adjustment step). Further, catalase, which is a hydrogen peroxide decomposing enzyme, is added through the catalase adding pipe 34 to decompose hydrogen peroxide (hydrogen peroxide decomposing step). The ammonia-containing wastewater whose hydrogen peroxide has been decomposed and adjusted to pH 10 or higher is sent to the ammonia stripping treatment device 12 through the raw water pipe 20, and thereafter the ammonia-containing wastewater treatment device 1 shown in FIG. It is processed through a stripping treatment step, a primary reverse osmosis membrane treatment step, a secondary reverse osmosis membrane treatment step, and a circulation step.

  In the ammonia-containing waste water treatment apparatus 2 of FIG. 2, the raw water tank 10 functions as a hydrogen peroxide decomposition means. The secondary concentrated water is circulated to the raw water tank 10 which is a hydrogen peroxide decomposition means. An enzyme treatment tank may be provided between the raw water tank 10 and the ammonia stripping treatment device 12 separately from the raw water tank 10, and catalase may be added to the ammonia-containing wastewater whose pH is adjusted to 10 or more in the enzyme treatment tank. In this case, the secondary concentrated water is circulated to the raw water tank 10 on the upstream side of the enzyme treatment tank which is a hydrogen peroxide decomposition means.

  Here, ammonia may be an inhibitor of catalase decomposition of hydrogen peroxide, but the raw water is diluted with secondary concentrated water (the ammonia concentration is lower than the ammonia concentration contained in the raw water). Since the ammonia concentration in the water is lowered, an effect of improving the efficiency of hydrogen peroxide decomposition in the raw water tank 10 is obtained.

  In addition to the configuration of the ammonia-containing wastewater treatment device 1 of FIG. 1, the ammonia-containing wastewater treatment device 3 of FIG. 3 includes an activated carbon treatment device 36 between the raw water tank 10 and the ammonia stripping treatment device 12. The outlet of the raw water tank 1 and the inlet of the activated carbon treatment device 36 are connected by a raw water pipe 38, and the outlet of the activated carbon treatment device 36 and the inlet of the ammonia stripping treatment device 12 are connected by an activated carbon treated water pipe 40.

  Ammonia-containing wastewater containing hydrogen peroxide as raw water is sent to the raw water tank 10 through the raw water pipe 18 and stored. In the raw water tank 10, an alkaline agent is added to the ammonia-containing wastewater, and the pH is adjusted to 10 or more (first pH adjustment step). The ammonia-containing wastewater adjusted to pH 10 or higher is sent to the activated carbon treatment device 36 through the raw water pipe 38, and activated carbon treatment is performed in the activated carbon treatment device 36 to decompose hydrogen peroxide (hydrogen peroxide decomposition step). The activated carbon treated water subjected to the activated carbon treatment is sent to the ammonia stripping treatment device 12 through the activated carbon treated water piping 40, and in the same manner as the ammonia-containing waste water treatment device 1 shown in FIG. It is processed through a secondary reverse osmosis membrane treatment step, a secondary reverse osmosis membrane treatment step, and a circulation step.

  In the ammonia-containing wastewater treatment apparatus 3 of FIG. 3, the activated carbon treatment apparatus 36 functions as a hydrogen peroxide decomposition means. The secondary concentrated water is circulated to the raw water tank 10 on the upstream side of the activated carbon treatment device 36 that is a hydrogen peroxide decomposition means.

  Here, since the hydrogen peroxide decomposition by activated carbon becomes good on the alkali side, it is considered that the hydrogen peroxide decomposition is favorably performed by treating the ammonia-containing wastewater adjusted to pH 10 or higher with activated carbon.

  Examples of the method for decomposing hydrogen peroxide include enzyme treatment using an enzyme such as catalase, activated carbon treatment using activated carbon, metal catalyst treatment using a metal catalyst such as manganese, and reduction treatment using a reducing agent such as sodium bisulfite. From the viewpoint of cost and residual components, enzyme treatment and activated carbon treatment are preferred.

  A treatment apparatus for ammonia-containing wastewater having a hydrogen peroxide decomposition means as shown in FIGS. 2 and 3 and a method for treating ammonia-containing wastewater including a hydrogen peroxide decomposition step are intended for treating ammonia-containing wastewater containing hydrogen peroxide. However, the ammonia concentration is 500 mg / L or more, the hydrogen peroxide is 1,000 mg / L or more, preferably the ammonia concentration is 1,000 mg / L or more, and the hydrogen peroxide is 1,000 mg / L or more. It is suitably applied to the treatment of wastewater containing high concentration ammonia containing a high concentration of hydrogen peroxide.

  The schematic structure of the other example of the processing apparatus of the ammonia containing waste_water | drain which concerns on this embodiment is shown in FIG. In addition to the configuration of the ammonia-containing wastewater treatment device 1 of FIG. 1, the ammonia-containing wastewater treatment device 4 of FIG. 4 includes a heat exchange device 42 between the raw water tank 10 and the ammonia stripping treatment device 12. The outlet of the raw water tank 10 and the raw water inlet of the heat exchange device 42 are connected by a raw water pipe 44, and the raw water outlet of the heat exchange device 42 and the inlet of the ammonia stripping treatment device 12 are connected by a pipe 46. The ammonia stripping treatment water outlet of the ammonia stripping treatment device 12 and the ammonia stripping treatment water inlet of the heat exchange device 42 are connected by a pipe 48, and the ammonia stripping treatment water outlet of the heat exchange device 42 and the primary reverse osmosis membrane are connected. The inlet of the processing device 14 is connected by a pipe 50.

  The ammonia-containing waste water that is raw water is sent to the raw water tank 10 through the raw water pipe 18 and stored. In the raw water tank 10, an alkaline agent is added to the ammonia-containing wastewater, and the pH is adjusted to 10 or more (first pH adjustment step). The ammonia-containing wastewater adjusted to a pH of 10 or more is fed to the ammonia stripping treatment device 12 through the raw water piping 44 through the heat exchange device 42 and through the piping 46, and the ammonia stripping treatment at pH 10 or more in the stripping treatment device 12. (Ammonia stripping treatment step).

  The ammonia stripped water that has been subjected to the ammonia stripping treatment is sent to the primary reverse osmosis membrane treatment device 14 through the pipe 50 via the heat exchange device 42 and through the pipe 50. The water temperature of the ammonia stripping treated water is usually about 80 ° C. to 100 ° C., but is passed through the heat exchanging device 42 to exchange heat with the ammonia-containing waste water, which is the raw water, so that the water temperature is 30 ° C. to 40 ° Decrease to about ℃ In this way, heat energy can be used efficiently. Heat-exchanged ammonia stripping treated water is treated through a primary reverse osmosis membrane treatment step, a secondary reverse osmosis membrane treatment step, and a circulation step in the same manner as the ammonia-containing wastewater treatment apparatus 1 shown in FIG. The

  In this embodiment, the ammonia-containing wastewater to be treated is not particularly limited as long as it contains ammonia, and examples thereof include wastewater discharged from a wafer cleaning process in a semiconductor-related factory.

  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.

<Example 1>
High-concentration ammonia-containing wastewater containing 1,100 mg / L ammonia was treated using the ammonia-containing wastewater treatment apparatus 5 shown in FIG. The ammonia-containing wastewater treatment device 5 shown in FIG. 5 includes a relay tank 52 between the ammonia stripping treatment device 12 and the primary reverse osmosis membrane treatment device 14 in addition to the configuration of the ammonia-containing wastewater treatment device 4 of FIG. A microfiltration device 54. The ammonia stripping water outlet of the heat exchanger 42 and the inlet of the relay tank 52 are connected by a pipe 50, and the outlet of the relay tank 52 and the inlet of the microfiltration apparatus 54 are connected by a pipe 56, The outlet and the inlet of the primary reverse osmosis membrane treatment apparatus 14 are connected by a pipe 58. The microfiltration device 54 was installed to protect the reverse osmosis membrane in the latter stage.

  The pH of the wastewater containing high concentration ammonia to be treated was 10.2. In the raw water tank 10, a sodium hydroxide aqueous solution was added to adjust the pH of the wastewater containing high concentration ammonia to 10.5. In the ammonia stripping treatment apparatus 12, the treatment was performed by heating the water temperature to 90 ° C. by contacting with the steam. In the ammonia stripping treatment, the ammonia concentration of the ammonia stripping treated water was reduced to 14 mg / L. The ammonia stripping water was heat-exchanged with the raw water by the heat exchanger 42, and the water temperature dropped to 36 ° C. In the ammonia stripping treatment, the pH of the ammonia stripping treated water was lowered to 9.2. Therefore, the aqueous solution of sodium hydroxide was added in the relay tank 52 to adjust the pH of the ammonia stripping treated water to 10.0. In the microfiltration process using the microfiltration apparatus 54, the particulate matter contained in the ammonia stripping process water was removed using a microfiltration membrane having a filtration pore diameter of 30 μm.

  In the first-stage reverse osmosis membrane treatment, primary permeate was obtained at a recovery rate of 85%. The first stage reverse osmosis membrane treated water (ammonia stripping treated water) contains 14 mg / L ammonia, 9 mg / L calcium, 16 mg / L sulfate ions, and 1.1 mg / L TOC. It was. In the primary permeated water of the first-stage reverse osmosis membrane treatment, most of ammonia remained at 13 mg / L. However, calcium and sulfate ions as scale components were 1 mg / L or less, and the slime contamination substances The TOC was 1 mg / L or less.

  Hydrochloric acid was added to the primary permeated water in the first-stage reverse osmosis membrane treatment to adjust the pH of the water to be treated in the second-stage reverse osmosis membrane treatment to 6.8.

  In the second-stage reverse osmosis membrane treatment, secondary permeated water was obtained at a recovery rate of 90%. The treated water (primary permeate) of the second-stage reverse osmosis membrane treatment contained 13 mg / L of ammonia, but the secondary permeate of the second-stage reverse osmosis membrane treatment contained ammonia. Ions were 1.4 mg / L, and most of them were removed. The secondary permeated water from the second-stage reverse osmosis membrane treatment is high-purity water from which ions, organic substances, etc. are well removed, and is recovered and reused for miscellaneous water such as pure water production equipment and cooling water. It became possible to do.

  On the other hand, the secondary concentrated water of the second-stage reverse osmosis membrane treatment contained 115 mg / L of ammonia ions, but calcium ions and sulfate ions as scale components were 1 mg / L or less, and the slime contamination causative substances and The TOC was 1 mg / L or less. Table 1 shows the water quality in each step in Example 1.

  When the secondary concentrated water of the second stage reverse osmosis membrane treatment was circulated to the raw water tank 10 and a long-term operation was performed for 35 days, the ammonia removal performance in the ammonia stripping treatment was hardly deteriorated. Also, the water flow differential pressure in the second-stage reverse osmosis membrane treatment hardly increased.

<Comparative Example 1>
High-concentration ammonia-containing wastewater containing 1,100 mg / L of ammonia was treated using the ammonia-containing wastewater treatment device 6 shown in FIG. The same treatment as in Example 1 was performed until the ammonia stripping treatment. In the relay tank 52, hydrochloric acid was added to adjust the pH of the ammonia stripping water to 6.8. In the microfiltration process using the microfiltration apparatus 54, the particulate matter contained in the ammonia stripping process water was removed using a microfiltration membrane having a filtration pore diameter of 30 μm.

  In the reverse osmosis membrane treatment using the reverse osmosis membrane treatment device 60, permeated water was obtained at a recovery rate of 85%. The treated water (ammonia stripping treated water) of the reverse osmosis membrane treatment contains 15 mg / L of ammonia ions, 8 mg / L of calcium ions, 16 mg / L of sulfate ions, and 1.3 mg / L of TOC. It was. In the permeated water of the reverse osmosis membrane treatment, ammonia ions are 1.8 mg / L, calcium and sulfate ions as scale components are 1 mg / L or less, and TOC that is a slime contaminant is 1 mg / L or less. It was. The permeated water of the reverse osmosis membrane treatment is highly purified water from which ions, organic substances, etc. are well eliminated, and can be recovered and reused for miscellaneous water such as pure water production equipment and cooling water. It was.

  On the other hand, the concentrated water of the reverse osmosis membrane treatment contained 88 mg / L of ammonia ions, but calcium ions as scale components were 50 mg / L, sulfate ions were 102 mg / L, and TOC that was a slime contamination causative agent was It was concentrated to 5.1 mg / L or less. Table 2 shows the water quality in each step in Comparative Example 1.

  When the concentrated water of this reverse osmosis membrane treatment was circulated to the raw water tank 10 and a long-term operation was carried out for 33 days, the ammonia removal performance gradually decreased in the ammonia stripping treatment, and the water flow differential pressure was reduced in the reverse osmosis membrane treatment. It gradually rose.

  As described above, in the treatment of Example 1, in the combination of the ammonia stripping treatment and the two-stage reverse osmosis membrane treatment having different pH, the ionic components and organic substances that cause the scaling and slime contamination are in one stage. Concentrated and eliminated by the reverse osmosis membrane treatment of the eye, the ammonia is concentrated and circulated by the reverse osmosis membrane treatment of the second stage, so that the ionic component can be eliminated without adding chemicals such as scale dispersant and slime control agent in the system. It has become possible to efficiently remove ammonia by reducing scaling and slime contamination by organic matter.

  1, 2, 3, 4, 5, 6 Ammonia-containing wastewater treatment device, 10 raw water tank, 12 ammonia stripping treatment device, 14 primary reverse osmosis membrane treatment device, 16 secondary reverse osmosis membrane treatment device, 18, 20, 38,44 Raw water piping, 22 Ammonia stripping treated water piping, 24 Primary permeated water piping, 26 Treated water piping, 28 Secondary concentrated water circulation piping, 30 Ammonia gas piping, 32 Primary concentrated water piping, 34 Catalase addition piping, 36 activated carbon treatment equipment, 40 activated carbon treatment water piping, 42 heat exchange equipment, 46, 48, 50, 56, 58 piping, 52 relay tank, 54 microfiltration equipment, 60 reverse osmosis membrane treatment equipment.

Claims (4)

Hydrogen peroxide decomposition means for decomposing hydrogen peroxide in ammonia-containing wastewater containing ammonia and hydrogen peroxide,
Ammonia stripping treatment means for ammonia-stripping the hydrogen peroxide-decomposed wastewater at a pH of 10 or higher;
A primary reverse osmosis membrane treatment means for subjecting the ammonia stripping treated water to a first-stage reverse osmosis membrane treatment at a pH of 10 or more and separating it into primary permeate and primary concentrated water;
A secondary reverse osmosis membrane treatment means for performing a second-stage reverse osmosis membrane treatment of the primary permeable water at a pH of 8.5 or less and separating the primary permeable water into secondary permeable water and secondary concentrated water;
A circulating means for circulating the secondary concentrated water to the hydrogen peroxide decomposing means or to the upstream side of the hydrogen peroxide decomposing means ;
An ammonia-containing wastewater treatment apparatus, comprising: The ammonia-containing wastewater treatment apparatus according to claim 1 ,
The ammonia-containing wastewater treatment apparatus, wherein the hydrogen peroxide decomposition means decomposes hydrogen peroxide by an enzyme treatment using catalase. A hydrogen peroxide decomposition process for decomposing hydrogen peroxide in ammonia-containing wastewater containing ammonia and hydrogen peroxide;
An ammonia stripping treatment step in which ammonia-containing wastewater in which hydrogen peroxide is decomposed is subjected to ammonia stripping treatment at a pH of 10 or more;
A primary reverse osmosis membrane treatment step in which the ammonia stripping treatment water subjected to the ammonia stripping treatment is subjected to a first-stage reverse osmosis membrane treatment at a pH of 10 or more and separated into a primary permeate and a primary concentrated water;
A secondary reverse osmosis membrane treatment step in which the primary permeate is subjected to a second-stage reverse osmosis membrane treatment at a pH of 8.5 or less and separated into secondary permeate and secondary concentrated water;
A circulation step of circulating the secondary concentrated water to the hydrogen peroxide decomposition step or to the upstream side of the hydrogen peroxide decomposition step ;
A method for treating ammonia-containing wastewater, comprising: A method for treating ammonia-containing wastewater according to claim 3 ,
A method for treating ammonia-containing wastewater, wherein in the hydrogen peroxide decomposition step, hydrogen peroxide is decomposed by an enzyme treatment using catalase.

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