TWI613153B - Treatment device for ammonia-containing wastewater and treatment method for ammonia-containing wastewater - Google Patents

Description

Treatment device for ammonia-containing wastewater and treatment method for ammonia-containing wastewater

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

As a treatment method for ammonia-containing ammonia-containing wastewater, a method of combining ammonia stripping treatment with reverse osmosis membrane treatment is known, and the ammonia stripping treatment is ammonia nitrogen. (Ammonia nitrogen) is formed into ammonia gas and is evaporated.

For example, Patent Document 1 describes a method for treating ammonia-containing wastewater by subjecting an ammonia-containing wastewater to a reverse osmosis membrane treatment, and adding a scale dispersant to the separated concentrated water, followed by pH (pH) The ammonia stripping treatment is performed under the condition of 10 or more, and the ammonia gas taken out is decomposed; wherein the reverse osmosis membrane treatment step comprises the following steps: a reverse osmosis membrane treatment step, which performs reverse osmosis membrane treatment on the ammonia-containing wastewater Separating into primary filtered water and primary concentrated water; secondary reverse osmosis membrane treatment step, which performs reverse osmosis membrane treatment on primary filtered water to separate it into secondary filtered water and secondary concentrated water; and, once concentrated water a reverse osmosis membrane treatment step of subjecting the primary concentrated water to a reverse osmosis membrane treatment to separate it into filtered water and concentrated water; and, performing concentrated water The ammonia stripping treatment, on the other hand, delivers the secondary concentrated water and the filtered water to the front stage of the primary reverse osmosis membrane treatment step.

However, in the method of Patent Document 1, there is a problem that the chemical cost of the scale dispersant is required, and it is difficult to optimize the amount of addition of the chemical according to the change in the water quality in the ammonia-containing wastewater.

On the other hand, there is a method in which an ammonia stripping treatment is carried out under conditions of pH 10 or higher for ammonia-containing wastewater, followed by reverse osmosis membrane treatment.

When this method is used to treat high-concentration ammonia-containing wastewater containing a high concentration of ammonia (for example, an ammonia concentration of 500 mg/L or more), it is difficult to completely remove ammonia by ammonia stripping treatment, and sometimes ammonia residue is left in the treated water. A few tens of milligrams per liter (for example, about 20 mg / L) of ammonia.

When the ammonia stripping treatment water in which ammonia remains is adjusted to pH 7 or lower and then subjected to reverse osmosis membrane treatment, the filtered water becomes high-purity water in which ammonia, other ionic components, and organic substances are removed, and the pure water producing apparatus can be used. Reuse in water for miscellaneous use.

However, since ammonia, other ionic components, organic substances, and the like are concentrated in the concentrated water treated by the reverse osmosis membrane, it is necessary to carry out wastewater treatment for further removing ammonia so that the concentration of ammonia is below the wastewater standard.

In order to avoid this further wastewater treatment for removing ammonia, it is thought that ammonia is treated by circulating the concentrated water treated by the reverse osmosis membrane to the front side of the ammonia stripping treatment, but there are the following problems: other ion components and organic substances are also caused. It is concentrated and circulated in the reverse osmosis membrane treatment together with ammonia, and in the distillation tower and the reverse osmosis membrane of the ammonia stripping treatment, scale formation of ionic components and slime contamination by organic substances are generated, and the treatment performance is lowered.

In order to solve this problem, in the same manner as the method of Patent Document 1, a scale dispersant or a slime control agent is added to the system to suppress scale formation of the ion component and organic matter. Mud contamination, but this method has the following problems: it still costs a chemical such as scale dispersant, and it is difficult to optimize the amount of chemical added according to the water quality change in the ammonia-containing wastewater, and new scale is generated. The need to dispose of the organic matter contained in the dispersant and slime inhibitor.

[Previous Technical Literature] (Patent Literature)

Patent Document 1: Japanese Patent No. 3667597

An object of the present invention is to provide a treatment apparatus for ammonia-containing wastewater and a treatment method for ammonia-containing wastewater, which does not use chemicals such as scale dispersants and slime inhibitors, even in high concentration. Ammonia wastewater can also be treated efficiently.

The invention relates to a treatment device for ammonia-containing wastewater, which comprises: an ammonia stripping treatment method, which performs ammonia stripping treatment under conditions of pH 10 or higher; and a reverse osmosis membrane treatment method, which passes through the ammonia The ammonia stripping treatment water after the stripping treatment is subjected to the reverse osmosis membrane treatment of the first stage under the condition of pH 10 or higher, and is separated into one filtered water and one concentrated water; and two reverse osmosis membrane treatment means, which will be the above 1 The second filtered water is subjected to the second stage reverse osmosis membrane treatment under the condition of pH 8.5 or lower, and is separated into two filtered waters and two concentrated waters; The circulation means circulates the aforementioned two times of concentrated water to the front side of the ammonia stripping treatment means.

Further, in the treatment apparatus for ammonia-containing wastewater, the ammonia-containing wastewater further contains hydrogen peroxide; and the front side of the ammonia stripping treatment means is provided to decompose hydrogen peroxide in the ammonia-containing wastewater. The hydrogen peroxide decomposition means, wherein the circulation means circulates the secondary concentrated water to the front side of the hydrogen peroxide decomposition means or the hydrogen peroxide decomposition means.

Further, preferably, in the treatment apparatus for ammonia-containing wastewater, the hydrogen peroxide decomposition means decomposes hydrogen peroxide by treatment with an enzyme of catalase.

Moreover, the present invention is a method for treating ammonia-containing wastewater, comprising: an ammonia stripping treatment step of subjecting ammonia-containing wastewater to ammonia stripping treatment under conditions of pH 10 or higher; and a reverse osmosis membrane treatment step, which will pass The ammonia stripping treatment water after the ammonia stripping treatment is subjected to the first stage reverse osmosis membrane treatment under the condition of pH 10 or higher, and is separated into one filtered water and one concentrated water; and two reverse osmosis membrane treatment steps, which will The second filtered water is subjected to a second stage reverse osmosis membrane treatment under the condition of pH 8.5 or lower, and is separated into two filtered waters and two concentrated waters; and a recycling step of circulating the above two concentrated waters to the ammonia The front side of the stripping treatment.

Further, preferably, in the method for treating ammonia-containing wastewater, the ammonia-containing wastewater further contains hydrogen peroxide; and the front side of the ammonia stripping treatment step includes decomposing hydrogen peroxide in the ammonia-containing wastewater. The hydrogen peroxide decomposition step; in the above-described circulation step, the above-mentioned two times of concentrated water is circulated to the front side of the hydrogen peroxide decomposition step or the aforementioned hydrogen peroxide decomposition step.

Further, preferably, in the method for treating ammonia-containing wastewater, in the hydrogen peroxide decomposition step, hydrogen peroxide is decomposed by treatment with an enzyme of catalase.

In the present invention, the ammonia-containing wastewater is subjected to ammonia stripping treatment under the conditions of pH 10 or higher, and then the ammonia stripping treatment water is subjected to the reverse osmosis membrane treatment in the first stage under the condition of pH 10 or higher, and the filtered water is filtered once. The second-stage reverse osmosis membrane treatment is carried out under the conditions of pH 8.5 or less, and the secondary concentrated water is circulated to the front side of the ammonia stripping treatment means, thereby eliminating the use of chemicals such as scale dispersants and slime inhibitors. Even high-concentration ammonia-containing wastewater can be processed efficiently.

1, 2, 3, 4, 5, 6‧‧‧ ammonia-containing wastewater treatment plant

10‧‧‧ original sink

12‧‧‧Ammonia extraction device

14‧‧‧1 reverse osmosis membrane treatment device

16‧‧‧2 reverse osmosis membrane treatment equipment

18, 20, 38, 44‧‧‧ raw water piping

22‧‧‧Ammonia extraction water treatment pipe

24‧‧1 times filtered water piping

26‧‧‧Processing water piping

28‧‧‧2 times concentrated water circulation piping

30‧‧‧Ammonia gas piping

32‧‧1 times concentrated water piping

34‧‧‧Catalase addition piping

36‧‧‧Active carbon treatment unit

40‧‧‧Active carbon treated water piping

42‧‧‧Heat exchange unit

46, 48, 50, 56, 58‧‧‧ piping

52‧‧‧Relay slot

54‧‧‧Precision filter

60‧‧‧Reverse osmosis membrane treatment unit

Fig. 1 is a schematic configuration diagram showing an example of an ammonia-containing wastewater treatment apparatus according to an embodiment of the present invention.

Fig. 2 is a schematic block diagram showing another example of the ammonia-containing wastewater treatment apparatus according to the embodiment of the present invention.

Fig. 3 is a schematic block diagram showing another example of the ammonia-containing wastewater treatment apparatus according to the embodiment of the present invention.

Fig. 4 is a schematic block diagram showing another example of the ammonia-containing wastewater treatment apparatus according to the embodiment of the present invention.

Fig. 5 is a schematic block diagram showing an ammonia-containing wastewater treatment apparatus used in Example 1.

Fig. 6 is a schematic block diagram showing an ammonia-containing wastewater treatment apparatus used in Comparative Example 1.

Figure 7 is a graph showing the relationship between pH, fraction of ammonia, and fraction of ammonia ions.

Hereinafter, embodiments of the present invention will be described. This embodiment is an example of the implementation of the present invention, and the present invention is not limited to the embodiment.

The outline of an example of the apparatus for treating ammonia-containing wastewater according to the embodiment of the present invention is shown in Fig. 1 and the configuration thereof will be described. The ammonia-containing wastewater treatment apparatus 1 includes a raw water tank 10, an ammonia gas extraction treatment device 12 as an ammonia gas extraction treatment means, a primary reverse osmosis membrane treatment device 14 as a primary reverse osmosis membrane treatment means, and a secondary reverse osmosis The second reverse osmosis membrane processing apparatus 16 of the membrane treatment means.

In the ammonia-containing wastewater treatment apparatus 1 of Fig. 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 device 12 are connected by the raw water pipe 20, and the ammonia gas is extracted. The ammonia stripping treatment water outlet of the treatment device 12 and the inlet of the primary reverse osmosis membrane treatment device 14 are connected by the ammonia stripping treatment water pipe 22, and the primary filtered water outlet of the primary reverse osmosis membrane treatment device 14 is twice. The inlet of the reverse osmosis membrane treatment device 16 is connected by the primary filtration water pipe 24, and the treatment water pipe 26 is connected to the secondary filtration water outlet of the secondary reverse osmosis membrane treatment device 16. An ammonia gas pipe 30 is connected to the ammonia gas outlet of the ammonia stripping treatment device 12, and one concentrated water pipe 32 is connected to the primary concentrated water outlet of the primary reverse osmosis membrane processing device 14, and the secondary reverse osmosis membrane processing device 16 is connected. The secondary concentrated water outlet port 28 is connected to the raw water tank 10 as 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 of the present embodiment will be described.

The raw water, that is, the ammonia-containing wastewater (for example, a 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. In the raw water tank 10, an alkaline reagent is added to the ammonia-containing wastewater, and the pH is adjusted to 10 or more (first pH adjustment step). When the pH of the ammonia-containing wastewater is already above pH 10, this pH adjustment may 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 will become free ammonia (NH ₃ ). Further, the alkaline reagent may be added to the raw water tank 10 or may be added to the raw water piping 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 the ammonia stripping treatment (ammonia stripping) is performed in the ammonia stripping treatment device 12 at a pH of 10 or higher. Processing steps).

The ammonia stripping treatment device 12 is, for example, provided with a porous plate and a filler in the inside of the distillation column, and the treated water, that is, the ammonia-containing wastewater, flows in from the upper portion of the distillation column, and the steam is blown in from the lower portion, and the treated water is in contact with the steam. Thereby, the free ammonia in the ammonia-containing wastewater is driven out on the steam side.

The ammonia gas that has been driven out is sent to the ammonia gas decomposition treatment device through the ammonia gas pipe 30, and is decomposed (ammonia gas decomposition treatment step). As the ammonia gas decomposition treatment, for example, there is a method of decomposing into harmless nitrogen by a catalyst-containing reaction column filled with a catalyst, a method of reacting with sulfuric acid to form ammonium sulfate, or the like; or ammonia water (ammonia water) ) The form is recycled and reused.

The ammonia stripping treatment water subjected to the ammonia stripping treatment is sent to the primary reverse osmosis membrane processing apparatus 14 by the ammonia stripping treatment water piping 22. Since the pH of the ammonia stripping treatment water is removed by the removal of most of the ammonia, the alkaline reagent is added to the ammonia stripping treatment water pipe 22 to adjust the pH to 10 or more (the second pH adjustment step). When the pH of the ammonia stripping treatment water is adjusted to 10 or more, most of the ammonia remaining in the ammonia stripping treatment water becomes free ammonia (NH ₃ ). Further, the alkaline reagent may be added to the pipeline in the ammonia stripping treatment water pipe 22, or a relay tank may be provided between the ammonia stripping treatment device 12 and the primary reverse osmosis membrane treatment device 14, and in the relay tank. Added in. Further, a filtration device such as a precision filtration device may be provided between the relay tank and the primary reverse osmosis membrane treatment device 14 to protect the reverse osmosis membrane in the subsequent stage.

The ammonia stripping treatment water adjusted to pH 10 or higher is subjected to the reverse osmosis membrane treatment in the first stage under the condition of pH 10 or higher in the primary reverse osmosis membrane treatment device 14, and is separated into one filtered water and one concentrated water. (1 reverse osmosis membrane treatment step).

In the reverse osmosis membrane treatment step, since the pH of the treated water, that is, the ammonia stripping treatment water is 10 or more, even if there are tens of milligrams per liter (for example, about 20 mg/L) of ammonia remaining, Most of them are free ammonia, so they are hardly concentrated and most of them remain in one filtered water. On the other hand, other ionic components and organic substances are equal to the first stage of the reverse osmosis membrane treatment, which is well concentrated and contained. In 1 concentrated water.

The primary concentrated water separated by the reverse osmosis membrane treatment of the first stage is discharged through the primary concentrated water piping 32. This concentrated water can also be sent to a wastewater treatment plant for wastewater treatment (wastewater treatment step). It is treated to the wastewater standard by wastewater treatment, but since the concentrated water contains almost no ammonia, the ammonia removal treatment for removing ammonia may not be performed.

Again, in a reverse osmosis membrane treatment step, by pH 10 The treatment under the above conditions makes it difficult for the living organism to survive on the reverse osmosis membrane, and the slime production in the reverse osmosis membrane treatment can be suppressed.

The primary filtered water separated by the reverse osmosis membrane treatment of the first stage is sent to the secondary reverse osmosis membrane processing apparatus 16 by the filtered water supply pipe 24 once. Here, the acid is added to the primary filtered water pipe 24 to adjust the pH to 8.5 or less (the third pH adjusting step). When the primary filtered water is adjusted to pH 8.5 or less, most of the free ammonia contained in the primary filtered water becomes ammonia ions (NH ₄ ⁺ ). Further, the acid may be added to the pipe in the primary filtration water pipe 24, or a relay tank may be provided between the primary reverse osmosis membrane treatment device 14 and the secondary reverse osmosis membrane treatment device 16, and in the relay tank. Add to.

The filtered water was adjusted to a pH of 8.5 or less, and the second reverse osmosis membrane treatment was carried out in the second reverse osmosis membrane treatment apparatus 16 under the conditions of pH 8.5 or less, and separated into two filtered waters and 2 Secondary concentrated water (2 reverse osmosis membrane treatment steps).

In the second reverse osmosis membrane treatment step, since the pH of the water to be treated, that is, the filtered water once is 8.5 or less, for example, several tens of milligrams per liter (for example, about 20 mg/L) contained in the filtered water is used. Most of the ammonia is ammonia ion, so it is concentrated by the reverse osmosis membrane treatment in the second stage, and most of it is contained in the secondary concentrated water. On the other hand, the second stage of the reverse osmosis membrane is treated with the second filtered water. The high-purity water, which is well-removed by ammonia and other ionic components and organic substances, is discharged through the treated water pipe 26, and can be recovered and reused in a miscellaneous water such as a pure water producing apparatus and cooling water.

Moreover, in the second reverse osmosis membrane treatment step, the organism is easily allowed to survive on the reverse osmosis membrane by treatment under the conditions of pH 8.5 or less, but The organic substance which is a source of nutrients and the ionic component which is a cause of scale formation have been excluded by the reverse osmosis membrane treatment of the first stage, and therefore, the generation of slime and scale formation in the reverse osmosis membrane treatment can be suppressed.

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

The secondary concentrated water separated by the reverse osmosis membrane treatment of the second stage contains, for example, several hundred milligrams per liter (for example, about 100 to 200 mg/L) of ammonia, and the second stage reverse osmosis membrane is used. The separated secondary concentrated water is circulated to the raw water tank 10 in the preceding stage, and ammonia stripping treatment is performed in the ammonia stripping treatment device 12, whereby ammonia can be effectively removed. The concentrated water twice may be circulated to the front side of the ammonia stripping treatment means, and may be circulated to the raw water tank 10 or may be circulated to the raw water piping 20.

In this way, in the combination of the ammonia stripping treatment and the reverse osmosis membrane treatment in which the treatment pH is different, the reverse osmosis membrane treatment in the first stage is an initiator substance such as scale formation and slime contamination. The ionic component and the organic substance are concentrated and removed, and the ammonia concentrating cycle is performed by the second-stage reverse osmosis membrane treatment, whereby the ionic component is scaled and the chemical is not added to the system by adding the scale dispersant and the slime inhibitor. Mud contamination caused by organic matter can also be suppressed, and even high concentrations of ammonia-containing wastewater can effectively remove ammonia.

In addition, the second-stage filtered water separated by the reverse osmosis membrane treatment in the second stage is used as a high-purity water in which ammonia and other ionic components and organic substances are well excluded, and can be used in a pure water production apparatus and cooling water. Recycled in water use.

It is difficult to completely remove ammonia contained in a high-concentration ammonia-containing wastewater containing, for example, ammonia having a concentration of 500 mg/L or more by a conventional method, and ammonia extraction is performed when a general ammonia stripping treatment is performed. Approximately tens of milligrams per liter of ammonia remains in the treated water. According to the ammonia-containing wastewater treatment method and the ammonia-containing wastewater treatment apparatus of the present embodiment, in the treatment of the high-concentration ammonia-containing wastewater, the alkali is first added, and ammonia is treated by ammonia stripping treatment using a distillation column or the like, but cannot be completely removed. Ammonia is left in the ammonia stripping treatment water. The treatment of the residual ammonia is carried out by the reverse osmosis membrane treatment in the first stage, and the treatment is carried out under the conditions of pH 10 or higher, so that most of the residual ammonia is permeated, and ions which become scale components and organic substances which become slime-inducing substances are excluded. In the second-stage reverse osmosis membrane treatment, the primary filtered water in the first stage is adjusted to pH 8.5 or lower, and the ammonia is concentrated and circulated to the raw water. By using the two-stage reverse osmosis membrane treatment to remove the ionic and organic substances from the circulation system and recycling the ammonia, it is possible to suppress scale formation and slime generation on the distillation tower and the reverse osmosis membrane of the ammonia stripping treatment, and Effectively remove ammonia.

The pH in the ammonia stripping treatment is 10 or more, preferably 10.5 or more, and more preferably in the range of 10.5 to 12. If the pH in the ammonia stripping treatment is less than 10, the relationship between the pH, the fraction of ammonia, and the fraction of ammonia ions, which is obtained from the dissociation constant of ammonia as shown in Fig. 7 The fraction of free ammonia (NH ₃ ) becomes low, and the removal efficiency of ammonia is lowered. If the pH in the ammonia stripping treatment exceeds 12, the following problem may occur: the porous plate and the filler inside the distillation column in the ammonia stripping treatment may be deteriorated, and the cost of the alkali chemical becomes high.

The higher the temperature, the more effective the ammonia stripping treatment is. Therefore, it is preferred. To raise the water temperature from 80 ° C to 100 ° C by steam. By raising the water temperature from 80 ° C to 100 ° C, the ammonia stripping treatment water is heat-sterilized, and the generation of slime in the reverse osmosis membrane in the latter stage is suppressed, which is also effective in this respect.

The pH in the primary reverse osmosis membrane treatment step is 10 or more, and in order to increase the fraction of free ammonia, it is preferably 10.5 or more, and more preferably 11 or more. Since a small amount of ammonia remains in the concentrated water, there is little problem as a waste water treatment. Therefore, from the viewpoint of reducing the amount of alkali added, the pH may be 10 or more. Further, the upper limit of the pH is preferably 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, and ammonia is concentrated to increase the content of ammonia in the primary concentrated water. If the pH in the reverse osmosis membrane treatment step exceeds 12, the following problems may occur: the reverse osmosis membrane is deteriorated, the amount of alkali addition is increased, the salt concentration is increased, the percolation pressure is increased, the amount of filtered water is decreased, and the desalination performance is lowered. .

The pH in the second reverse osmosis membrane treatment step is 8.5 or less, preferably 8 or less, more preferably 7 or less. The lower limit of the pH is preferably 5 or more. When the pH in the second reverse osmosis membrane treatment step exceeds 8.5, as shown in Fig. 7, the fraction of ammonia ions (NH ₄ ⁺ ) becomes low, and ammonia is permeated, and the content of ammonia in the secondary filtered water increases. If the pH in the second reverse osmosis membrane treatment step is less than 5, the following problems may occur: an increase in the amount of acid added, a high salt concentration, and a high percolation pressure, resulting in a decrease in the amount of filtered water and a decrease in desalting performance.

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

The concentrated water is circulated to the front side of the ammonia stripping treatment device 12 twice, and may be circulated to the raw water piping 18 in addition to the raw water tank 10.

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

Examples of other ionic components contained in the ammonia-containing wastewater include calcium ions, magnesium ions, and sulfate ions which are causes of scale formation.

Examples of the organic substance contained in the ammonia-containing wastewater include isopropyl alcohol, tetramethylammonium hydroxide, and the like.

The alkaline agent used in the pH adjustment may, for example, be an aqueous alkaline solution such as a sodium hydroxide solution; and examples of the acid include hydrochloric acid and sulfuric acid.

In the ammonia-containing wastewater, hydrogen peroxide is sometimes contained in addition to ammonia. A schematic configuration of an example of a treatment apparatus for a suitable ammonia-containing wastewater in the treatment of ammonia-containing wastewater containing hydrogen peroxide is shown in Fig. 2 and Fig. 3 .

In the ammonia-containing wastewater treatment apparatus 2 of Fig. 2, in addition to the configuration of the ammonia-containing wastewater treatment apparatus 1 of Fig. 1, a hydrogen peroxide enzyme addition pipe 34 is also connected to the raw water tank 10.

The raw water, that is, the ammonia-containing wastewater containing hydrogen peroxide (for example, a 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 original water pipe 18 and stored therein. In the sink 10 . In the raw water tank 10, an alkaline reagent is added to the ammonia-containing wastewater, and the pH is adjusted to 10 or more (first pH adjustment step). Further, the hydrogen peroxide decomposing enzyme, that is, the catalase, is added by the catalase addition pipe 34, and the hydrogen peroxide is decomposed (hydrogen peroxide decomposition step). The ammonia-containing wastewater which has been decomposed and adjusted to pH 10 or higher is sent to the ammonia gas through the raw water pipe 20 The treatment device 12 is carried out in the same manner as the ammonia-containing wastewater treatment device 1 shown in Fig. 1, and then subjected to an ammonia gas extraction treatment step, a primary reverse osmosis membrane treatment step, a secondary reverse osmosis membrane treatment step, and a circulation step. To handle.

In the ammonia-containing wastewater treatment apparatus 2 of Fig. 2, the raw water tank 10 functions as a hydrogen peroxide decomposition means. The concentrated water is circulated twice to the hydrogen peroxide decomposition means, that is, in the raw water tank 10. 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 adjusted to pH 10 or higher in the enzyme treatment tank. At this time, the concentrated water is circulated twice to the hydrogen peroxide decomposition means, that is, the front side of the enzyme treatment tank, that is, the raw water tank 10.

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

In the ammonia-containing wastewater treatment apparatus 3 of Fig. 3, in addition to the configuration of the ammonia-containing wastewater treatment apparatus 1 of Fig. 1, an activated carbon treatment apparatus 36 is also provided between the raw water tank 10 and the ammonia stripping treatment apparatus 12. The outlet of the raw water tank 10 and the inlet of the activated carbon processing apparatus 36 are connected by the raw water piping 38, and the outlet of the activated carbon processing apparatus 36 and the inlet of the ammonia stripping processing apparatus 12 are connected by the activated carbon processing water piping 40.

The raw water, that is, the ammonia-containing wastewater containing hydrogen peroxide, is sent through the raw water pipe 18 and is stored in the raw water tank 10. In the raw water tank 10, an alkaline reagent 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 unit 36 through the raw water piping 38, and subjected to activated carbon treatment in the activated carbon treatment unit 36 to decompose the hydrogen peroxide (hydrogen peroxide decomposition). step). The activated carbon-treated activated carbon-treated water is sent to the ammonia stripping treatment apparatus 12 by the activated carbon-treated water piping 40, and is carried out in the same manner as the ammonia-containing wastewater treatment apparatus 1 shown in Fig. 1, and then The ammonia stripping treatment step, the primary reverse osmosis membrane treatment step, the secondary reverse osmosis membrane treatment step, and the cycle step are treated.

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 hydrogen peroxide decomposition means, that is, the front side of the activated carbon processing apparatus 36, that is, the raw water tank 10.

Here, it is considered that since hydrogen peroxide by activated carbon is decomposed under alkaline conditions, the decomposition of hydrogen peroxide can be favorably performed by treating the activated carbon of the ammonia-containing wastewater adjusted to pH 10 or higher. .

Examples of the method for decomposing hydrogen peroxide include an enzyme treatment using an enzyme such as catalase, an activated carbon treatment using activated carbon, a metal catalyst treatment using a metal catalyst such as manganese, and use of sodium bisulfite (sodium bisulfite). The reduction treatment of the reducing agent or the like is preferably an enzyme treatment or an activated carbon treatment from the viewpoints of cost and residual components.

The treatment apparatus for the ammonia-containing wastewater having the hydrogen peroxide decomposition means shown in Figs. 2 and 3 and the treatment method of the ammonia-containing wastewater containing the hydrogen peroxide decomposition step are characterized in that the ammonia-containing wastewater containing hydrogen peroxide is used. The object to be treated is suitable for use in a high concentration ammonia-containing wastewater containing a high concentration of hydrogen peroxide having an ammonia concentration of 500 mg/L or more and hydrogen peroxide of 1,000 mg/L or more. The treatment is preferably a treatment of a high concentration ammonia-containing wastewater containing a high concentration of hydrogen peroxide having an ammonia concentration of 1,000 mg/L or more and a hydrogen peroxide of 1,000 mg/L or more.

The schematic configuration of another example of the apparatus for treating ammonia-containing wastewater according to the present embodiment is shown in Fig. 4. In the ammonia-containing wastewater treatment apparatus 4 of Fig. 4, in addition to the configuration of the ammonia-containing wastewater treatment apparatus 1 of Fig. 1, a heat exchange unit 42 is also provided between the raw water tank 10 and the ammonia stripping treatment apparatus 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 unit 42 are connected by a pipe 48, and the ammonia stripping treatment water outlet of the heat exchange unit 42 and the reverse osmosis membrane treatment are used. The inlet of the device 14 is connected by a pipe 50.

The raw water, that is, the ammonia-containing wastewater, is sent through the raw water pipe 18 and is stored in the raw water tank 10. In the raw water tank 10, an alkaline reagent 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 ammonia stripping treatment apparatus 12 through the piping 46 through the raw water piping 44 through the raw water piping 44, and the pH is 10 or more in the ammonia stripping treatment apparatus 12. The ammonia stripping treatment (ammonia stripping treatment step) is carried out.

The ammonia stripping treatment water subjected to the ammonia stripping treatment is sent to the primary reverse osmosis membrane processing apparatus 14 through the piping 50 through the piping 48 through the piping 50. The water temperature of the ammonia stripping treatment water is generally about 80 ° C to 100 ° C, but by transferring it to the heat exchange unit 42 , it is heated with the raw water, that is, the ammonia-containing waste water. When exchanged, the water temperature is reduced to about 30 ° C to 40 ° C. In this way, heat energy can be effectively utilized. The ammonia stripping treatment water after heat exchange is carried out in the same manner as the ammonia-containing wastewater treatment apparatus 1 shown in Fig. 1, and then treated by one reverse osmosis membrane treatment step, two reverse osmosis membrane treatment steps, and a circulation step. .

In the present embodiment, the ammonia-containing wastewater to be treated is not particularly limited, and may contain ammonia, and examples thereof include waste water discharged from a wafer cleaning step in a semiconductor-related factory.

[Examples]

Hereinafter, the present invention will be described in more detail and in detail by way of examples and comparative examples, but the invention is not limited to the following examples.

<Example 1>

The ammonia-containing wastewater treatment apparatus 5 shown in Fig. 5 was used to treat a high-concentration ammonia-containing wastewater containing 1100 mg/L of ammonia. The ammonia-containing wastewater treatment apparatus 5 shown in Fig. 5 is based on the configuration of the ammonia-containing wastewater treatment apparatus 4 of Fig. 4, between the ammonia stripping treatment apparatus 12 and the primary reverse osmosis membrane processing apparatus 14, A relay tank 52 and a precision filter device 54 are provided. The ammonia stripping treatment water outlet of the heat exchange device 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 precision filter device 54 are connected by a pipe 56, and the precision filter device 54 is connected. The outlet and the inlet of the primary reverse osmosis membrane processing apparatus 14 are connected by a pipe 58. The precision filtration device 54 is provided to protect the reverse osmosis membrane in the latter stage.

The pH of the high-concentration ammonia-containing wastewater to be treated was 10.2. In the raw water tank 10, an aqueous sodium hydroxide solution was added, and the pH of the high-concentration ammonia-containing wastewater was adjusted to 10.5. In the ammonia stripping treatment device 12, by contacting it with steam The water temperature was raised to 90 ° C and then treated. In the ammonia stripping treatment, the ammonia concentration of the ammonia stripping treatment water was lowered to 14 mg/L. The ammonia stripping treatment water is heat-exchanged with the raw water by the heat exchange device 42, and the water temperature is lowered to 36 °C. In the ammonia stripping treatment, since the pH of the ammonia stripping treatment water was lowered to 9.2, an aqueous sodium hydroxide solution was added to the relay tank 52 to adjust the pH of the ammonia stripping treatment water to 10.0. In the precision filtration treatment using the precision filtration device 54, a fine filtration membrane having a filtration pore size of 30 μm was used to remove particulate matter contained in the ammonia gasification treatment water.

In the reverse osmosis membrane treatment of the first stage, the filtered water was obtained once at a recovery rate of 85%. The treated water (ammonia stripping treated water) treated by the reverse osmosis membrane in the first stage contains 14 mg/L of ammonia, 9 mg/L of calcium, 16 mg/L of sulfate ion, and 1.1 mg/L of TOC (total Organic carbon). In the primary filtration water treated by the reverse osmosis membrane in the first stage, most of the 13 mg/L ammonia remains, but the calcium and sulfate ions of the scale component are 1 mg/L or less, which becomes the TOC of the slime contamination-inducing substance. The organic carbon) is 1 mg/L or less.

To the primary filtered water of the reverse osmosis membrane treatment of the first stage, hydrochloric acid was added to adjust the pH (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, filtered water was obtained twice at a recovery rate of 90%. The treated water (primary filtered water) treated by the reverse osmosis membrane in the second stage contains 13 mg/L of ammonia, but in the second filtered water treated by the reverse osmosis membrane of the second stage, the ammonia ion is 1.4 mg/ L, most of them were removed. The second-stage filtered water treated by the reverse osmosis membrane in the second stage is a high-purity water that is well removed, such as ions and organic substances, and can be used in pure water production equipment and cooling. Recycling and reuse of water and other miscellaneous water.

On the other hand, in the secondary concentrated water treated by the reverse osmosis membrane in the second stage, 115 mg/L of ammonia ions are contained, but the calcium ions and sulfate ions which are scale components are 1 mg/L or less, which is a slime-inducing substance. The TOC is 1 mg/L or less. The water quality in each step in Example 1 is shown in Table 1.

The second-stage concentrated water treated by the second-stage reverse osmosis membrane is circulated to the raw water tank 10, and after 35 days of long-term operation, the ammonia removal performance in the ammonia stripping treatment is hardly lowered, and the first stage and the second stage are performed. The water pressure difference in the reverse osmosis membrane treatment at the stage also hardly increased.

<Comparative Example 1>

The ammonia-containing wastewater treatment apparatus 6 shown in Fig. 6 was used to treat a high-concentration ammonia-containing wastewater containing 1,100 mg/L of ammonia. The same treatment as in Example 1 was carried out until the ammonia stripping treatment. Hydrochloric acid was added to the relay tank 52 to adjust the pH of the ammonia stripping treatment water to 6.8. In the precision filtration treatment using the precision filtration device 54, a fine filtration membrane having a filtration pore size of 30 μm was used to remove particulate matter contained in the ammonia gasification treatment water.

In the reverse osmosis membrane treatment using the reverse osmosis membrane treatment device 60, The recovery rate was 85% to obtain filtered water. The treated water (ammonia stripping treated water) treated with the reverse osmosis membrane contains 15 mg/L of ammonia ion, 8 mg/L of calcium ion, 16 mg/L of sulfate ion, and 1.3 mg/L of TOC. In the filtered water treated by the reverse osmosis membrane, the ammonia ion is 1.8 mg/L, the calcium and sulfate ions of the scale component are 1 mg/L or less, and the TOC of the slime-inducing substance is 1 mg/L or less. The filtered water treated by the reverse osmosis membrane is a high-purity water which is well excluded, such as an ion or an organic substance, and can be recovered and reused in a miscellaneous water such as a pure water production apparatus and cooling water.

On the other hand, in the concentrated water treated by the reverse osmosis membrane, 88 mg/L of ammonia ions are contained, but the calcium ions which become the scale component are concentrated to 50 mg/L, and the sulfate ions are concentrated to 102 mg/L, which becomes a slime contamination inducing substance. The TOC is concentrated to below 5.1 mg/L. The water quality in each step in Comparative Example 1 is shown in Table 2.

The concentrated water treated by the reverse osmosis membrane is circulated to the raw water tank 10, and after 33 days of long-term operation, the ammonia removal performance is gradually lowered in the ammonia stripping treatment, and the water delivery pressure difference is obtained in the reverse osmosis membrane treatment. Gradually rise.

As described above, in the treatment of Example 1, the first stage is utilized in the combination of the reverse osmosis membrane treatment in two stages of ammonia stripping treatment and pH difference. In the reverse osmosis membrane treatment, the ionic components and organic substances such as scale inhibitors and slime contamination are concentrated and removed, and the second stage reverse osmosis membrane treatment is used to condense the ammonia, thereby not adding the system to the system. The chemicals of the scale dispersant and the slime inhibitor, the scale of the ionic components and the slime contamination caused by the organic matter are also suppressed, and the ammonia can be effectively removed.

1‧‧‧Ammonia wastewater treatment plant

10‧‧‧ original sink

12‧‧‧Ammonia extraction device

14‧‧‧1 reverse osmosis membrane treatment device

16‧‧‧2 reverse osmosis membrane treatment equipment

18, 20‧‧‧ raw water piping

22‧‧‧Ammonia extraction water treatment pipe

24‧‧1 times filtered water piping

26‧‧‧Processing water piping

28‧‧‧2 times concentrated water circulation piping

30‧‧‧Ammonia gas piping

32‧‧1 times concentrated water piping

Claims (6)

The invention relates to a treatment device for ammonia-containing wastewater, characterized in that it comprises: an ammonia stripping treatment method, which carries out ammonia stripping treatment under the condition that the ammonia-containing wastewater is above pH 10; and one reverse osmosis membrane treatment means, which passes through the ammonia gas The treated ammonia stripping treatment water is subjected to the first stage reverse osmosis membrane treatment under the condition of pH 10 or higher, and is separated into one filtered water and one concentrated water; and two reverse osmosis membrane treatment means, which is the first time The filtered water is subjected to the second stage reverse osmosis membrane treatment under the condition of pH 8.5 or lower, and is separated into two filtered waters and two concentrated waters; and a circulation means for circulating the above two concentrated waters to the ammonia stripping treatment. The front side of the means; and the ammonia-containing wastewater is a high-concentration ammonia-containing wastewater having an ammonia concentration of 500 mg/L or more. The apparatus for treating ammonia-containing wastewater according to claim 1, wherein the ammonia-containing wastewater further contains hydrogen peroxide; and on the front side of the ammonia stripping treatment means, the hydrogen peroxide in the ammonia-containing wastewater is decomposed The hydrogen peroxide decomposition means; and the circulation means circulates the secondary concentrated water to the front side of the hydrogen peroxide decomposition means or the hydrogen peroxide decomposition means. The apparatus for treating ammonia-containing wastewater according to claim 2, wherein the hydrogen peroxide decomposition means decomposes hydrogen peroxide by treatment with an enzyme of catalase. The invention relates to a method for treating ammonia-containing wastewater, which comprises: an ammonia stripping treatment step, which carries out ammonia stripping treatment under the condition that the ammonia-containing wastewater is above pH 10; and one reverse osmosis membrane treatment step, which passes through the aforementioned ammonia gas The treated ammonia stripping treatment water is subjected to the first stage reverse osmosis membrane treatment under the condition of pH 10 or higher, and is separated into one filtered water and one concentrated water; and two reverse osmosis membrane treatment steps, which are the first time The filtered water is subjected to the second stage reverse osmosis membrane treatment under the condition of pH 8.5 or lower, and is separated into two filtered waters and two concentrated waters; and a recycling step of circulating the above two concentrated waters to the aforementioned ammonia stripping treatment The front side of the means; and the ammonia-containing wastewater is a high-concentration ammonia-containing wastewater having an ammonia concentration of 500 mg/L or more. The method for treating ammonia-containing wastewater according to claim 4, wherein the ammonia-containing wastewater further contains hydrogen peroxide; and the front side of the ammonia stripping treatment step comprises decomposing hydrogen peroxide in the ammonia-containing wastewater. The hydrogen peroxide decomposition step; in the above-described circulation step, the above-mentioned two times of concentrated water is circulated to the front side of the hydrogen peroxide decomposition step or the aforementioned hydrogen peroxide decomposition step. The method for treating ammonia-containing wastewater according to claim 5, wherein in the hydrogen peroxide decomposition step, hydrogen peroxide is decomposed by treatment with an enzyme of catalase.