JP2023177366A - Ammonia recovery apparatus - Google Patents

Abstract

To provide a recovery apparatus that efficiently recovers ammonia from a liquid to be treated that contains ammonia nitrogen and organic nitrogen.SOLUTION: An ammonia recovery apparatus includes: a first concentration mechanism 10 in which to-be-treated water containing ammonia nitrogen and organic nitrogen is separated by a first forward osmosis membrane into a first permeate liquid and a first concentrated liquid that does not permeate the membrane; an anaerobic membrane separation mechanism 20 in which the first concentrated liquid is subjected to anaerobic fermentation to decompose organic nitrogen into methane gas and ammonia nitrogen, and the anaerobic fermented liquid is subjected to permeation through a separation membrane to separate it into a liquid that contains microorganisms and does not permeate the separation membrane and a separation membrane permeate that has permeated it; a second concentration mechanism 30 in which the separation membrane permeate is subjected to permeation using a second forward osmosis membrane to separate it into a permeate that has passed through the second membrane and a second concentrate that has not permeated the membrane and shows an increased concentration of ammonia nitrogen; and a distillation mechanism 50 in which the second concentrate is distilled and separated into bottom liquid and distillate vapor that contains ammonia nitrogen at a high concentration.SELECTED DRAWING: Figure 1

Description

Application for application of Article 30, Paragraph 2 of the Patent Act has been filed Website publication date March 9, 2020 Publication address https://stin-2. webex. com/stin-2/j. php? MTID=m7cefd85273ea207d04c1c53834f72ac9

The present invention relates to an ammonia recovery apparatus, and more particularly to an ammonia recovery apparatus for recovering ammonia from a liquid to be treated containing ammonia nitrogen and organic nitrogen.

The reality is that industrial wastewater containing ammonia nitrogen, organic nitrogen, etc. cannot be discharged as is, due to laws regarding the regulation of the total amount of nitrogen.

For example, Patent Document 1 describes a methane fermentation process in which methane fermentation treated water is obtained by decomposing organic matter in a material to be treated using a methane fermentation method, and ammonia in the methane fermentation treated water is removed by the action of aerobic microorganisms. Treatment of a material to be treated, which includes a step of oxidizing to nitric acid and decomposing organic matter to obtain nitrified water, and an evaporative concentration step of evaporating and concentrating the nitrified water to obtain concentrated water and condensed water. A method is disclosed.

Further, Patent Document 1 describes a method for treating water with an ammonia concentration of 10 to 10,000 ppm in terms of nitrogen, a Cl concentration of 1 to 50,000 ppm, a COD of 10 to 100,000 ppm, and a BOD of 10 to 10,000 ppm, which method uses an aerobic method. An aerobic microbial treatment process that oxidizes ammonia in the water to be treated to nitric acid through the action of microorganisms and decomposes organic matter to obtain nitrified water; and evaporates and concentrates the nitrified water to produce concentrated water and condensed water. Disclosed is a method for treating water to be treated, which includes an evaporation concentration step to obtain the following:

According to the above-described method for treating a workpiece, it is possible to treat a workpiece containing organic matter, ammonia, and soluble salts at low equipment costs and operating costs.

JP2020-62631A

By the way, ammonia is used for various purposes as a raw material for fertilizers, melamine resin, synthetic fibers (nylon), etc., and in recent years, attention has been paid to its use as a fuel that does not generate carbon dioxide.

However, the method for treating the object disclosed in Patent Document 1 is configured to oxidize ammonia to nitric acid through the action of aerobic microorganisms, and therefore cannot recover ammonia.

The present invention solves the above problems, and aims to provide an ammonia recovery device that can efficiently recover ammonia from a liquid to be treated containing ammonia nitrogen, organic nitrogen, and water. shall be.

In order to solve the above problems, the ammonia recovery device of the present invention includes:
A first forward osmosis membrane permeated liquid that has permeated the first forward osmosis membrane by permeating the liquid to be treated containing ammonia nitrogen, organic nitrogen, and water using the first forward osmosis membrane. and a first concentration mechanism that does not pass through the first forward osmosis membrane and separates the liquid into a first concentrated liquid in which the components contained in the liquid to be treated are concentrated.
The first concentrated liquid concentrated by the first concentration mechanism is subjected to anaerobic fermentation by anaerobic microorganisms, thereby decomposing the organic nitrogen and converting it into methane gas and ammonia nitrogen, as well as anaerobic fermentation. A microorganism-containing liquid containing the anaerobic microorganisms that does not pass through the separation membrane by permeabilizing the subsequent anaerobic fermentation-treated liquid using a separation membrane having a pore size smaller than that of the anaerobic microorganisms; an anaerobic membrane separation mechanism that separates ammonia nitrogen that has passed through the separation membrane and a separation membrane permeate containing water;
A second forward osmosis membrane permeate that has passed through the second forward osmosis membrane by permeating the separation membrane permeate separated by the anaerobic membrane separation mechanism using a second forward osmosis membrane; a second concentration mechanism that does not pass through the second forward osmosis membrane and separates into a second concentrated liquid with an increased concentration of ammonia nitrogen;
The second concentrated liquid in which the concentration of ammonia nitrogen has been increased in the second concentration mechanism is distilled to produce a bottom liquor from which ammonia nitrogen has been removed, and ammonia nitrogen at a higher concentration than the second concentrated liquid. and a distillation mechanism that separates the distillate vapor from the distillate vapor containing the vapor.

The ammonia recovery apparatus of the present invention is preferably configured such that the total nitrogen concentration in the first concentrated liquid concentrated by the first concentration mechanism is 3000 ppm or less.

Further, it is preferable that the second concentration liquid, in which the concentration of ammonia nitrogen is increased in the second concentration mechanism, has a total nitrogen concentration of 15,000 ppm or less.

Further, in the first concentration mechanism, when permeation treatment is performed using the first forward osmosis membrane, the liquid to be treated is permeated through the first forward osmosis membrane while being in contact with the first driving solution. carrying out the treatment, and using a solution having a higher osmotic pressure than the liquid to be treated as the first driving solution,
In the second concentration mechanism, when performing permeation treatment using the second forward osmosis membrane, the permeation treatment is performed while the separation membrane permeate is brought into contact with the second driving solution through the second forward osmosis membrane. It is preferable that the second driving solution is configured such that a solution having a higher osmotic pressure than the separation membrane permeate is used as the second driving solution.

Further, as the first and second driving solutions, it is preferable to use at least one selected from the group consisting of seawater, inorganic salt-dissolved water, temperature-responsive ionic liquids, and temperature-responsive polymers.

Moreover, it is preferable that the second concentrated liquid is configured to be supplied to the distillation mechanism after the pH is adjusted to pH 9.0 or higher.

Moreover, it is preferable that a pH adjustment mechanism for adjusting the pH of the second concentrated liquid is provided.

As described above, the ammonia recovery device of the present invention includes a first concentration mechanism, an anaerobic membrane separation mechanism, a second concentration mechanism, and a distillation mechanism, and the first concentration mechanism includes a first forward osmosis mechanism. By performing permeation treatment using a membrane, we are trying to concentrate the components contained in the liquid to be treated, so compared to concentrating by a method that involves a phase change such as distillation, we are saving energy while liquid can be concentrated.

In addition, the first concentration mechanism uses a forward osmosis membrane to concentrate by the forward osmosis method, so it can save energy compared to the case of concentrating by the reverse osmosis method using a reverse osmosis membrane. .

In addition, since the first concentrated liquid concentrated in the first concentration mechanism is subjected to anaerobic fermentation by anaerobic microorganisms, organic nitrogen is decomposed and converted into methane gas and ammonia nitrogen, and anaerobic fermentation By permeabilizing the anaerobic fermentation solution using a separation membrane with a pore size smaller than that of the anaerobic microorganisms, the microorganism-containing solution that does not pass through the separation membrane and the ammonia nitrogen that has passed through the separation membrane are separated. It becomes possible to separate the ammonia nitrogen into a separation membrane permeate liquid containing water and water, and the recovery rate of ammonia nitrogen can be improved.

Furthermore, since organic nitrogen is decomposed and converted into methane gas, the generated methane gas can be effectively used as energy for power generation equipment, for example.

Furthermore, in the case of anaerobic fermentation, there is no need for aeration, which is required in the case of aerobic fermentation, so energy can be saved.

Furthermore, in the second concentration mechanism, the separation membrane permeate separated by the anaerobic membrane separation mechanism is permeated using the second forward osmosis membrane, so water is separated as the forward osmosis membrane permeate. As a result, a second concentrated liquid having a high concentration of ammonia nitrogen can be obtained.

In addition, the second concentration mechanism also uses a forward osmosis membrane to concentrate by the forward osmosis method, so it is possible to save energy compared to the case of concentrating by the reverse osmosis method using a reverse osmosis membrane. .

Furthermore, in the distillation mechanism, a second concentrate with an increased concentration of ammonia nitrogen is distilled in a second concentration mechanism, and a bottom liquid containing no ammonia nitrogen and a bottom liquid with a higher concentration than the second concentrate are distilled. Since the vapor is separated from the distilled vapor containing ammonia nitrogen, the distilled vapor containing a high concentration of ammonia nitrogen (ie, ammonia) can be recovered.

As described above, according to the ammonia recovery device of the present invention that combines the first concentration mechanism, anaerobic membrane separation mechanism, second concentration mechanism, and distillation mechanism, it is possible to save energy while recovering highly concentrated ammonia. It becomes possible to collect efficiently.

In addition, when concentrating by forward osmosis in the first concentration mechanism, if the concentration of total nitrogen derived from ammonia nitrogen or organic nitrogen becomes too high, biological treatment in the anaerobic membrane separation mechanism, which is a subsequent process, may occur. However, by suppressing the total nitrogen concentration in the first concentrated liquid concentrated by the first concentration mechanism to 3000 ppm or less, the decrease in biological treatment efficiency in the anaerobic membrane separation mechanism is suppressed. It becomes possible to do so.

In addition, the anaerobic membrane separation mechanism allows anaerobic fermentation using anaerobic microorganisms to decompose organic nitrogen and convert it into methane gas and ammonia nitrogen, making it possible to efficiently recover methane gas and ammonia nitrogen. becomes possible.

In addition, in the ammonia recovery apparatus of the present invention, when the concentration of total nitrogen (ammonia nitrogen) in the second concentrated liquid concentrated by the forward osmosis method in the second concentration mechanism is 15,000 ppm or less, the second concentration Ammonia nitrogen can be efficiently concentrated by suppressing a decrease in the concentration rate in the mechanism.

In addition, in the first concentration mechanism, when performing permeation treatment using the first forward osmosis membrane, the permeation treatment is performed while the liquid to be treated is in contact with the first driving solution through the first forward osmosis membrane, In addition, when a solution having a higher osmotic pressure than the liquid to be treated is used as the first driving solution and a second forward osmosis membrane is used for permeation treatment in the second concentration mechanism, the separation membrane in the anaerobic membrane separation mechanism is used. The permeate through the separation membrane is subjected to permeation treatment in a state in which it is brought into contact with the second driving solution via the second forward osmosis membrane, and as the second driving solution, the liquid having an osmotic pressure higher than that of the separation membrane permeate is used as the second driving solution. When a high concentration solution is used, efficient concentration can be performed in the first and second concentration mechanisms.

Further, by using at least one selected from the group consisting of seawater, inorganic salt dissolved water, temperature-responsive ionic liquid, and temperature-responsive polymer as the first and second driving solutions, the first and second concentration mechanisms , it becomes possible to reliably perform efficient concentration.

Furthermore, in the ammonia recovery apparatus of the present invention, if the second concentrated liquid is supplied to the distillation mechanism after adjusting the pH to 9.0 or higher, ammonia nitrogen is liberated as NH3, so the distillation It becomes possible to reliably separate and recover ammonia (ammonium nitrogen) in the mechanism.

In addition, in another ammonia recovery apparatus of the present invention, by having a configuration equipped with a pH adjustment mechanism for adjusting the pH of the second concentrated liquid, it becomes possible to easily and reliably adjust the pH, and the present invention The invention can be made more effective.

1 is a flow sheet showing an ammonia recovery apparatus according to an embodiment of the present invention.

Embodiments of the present invention will be shown below, and features of the present invention will be explained in more detail.

The ammonia recovery device 100 according to the embodiment of the present application is an ammonia recovery device used to recover ammonia from a liquid to be treated containing ammonia nitrogen, organic nitrogen, inorganic salts, and water. Note that the liquid to be treated may contain organic substances other than ammonia nitrogen and organic nitrogen.

Furthermore, the ammonia recovery apparatus 100 according to the present embodiment is capable of recovering methane gas (specifically, biogas whose main component is methane and which can be used as fuel for power generation, etc.) from the liquid to be treated. It is composed of

As shown in FIG. 1, the ammonia recovery apparatus 100 includes a first concentration mechanism 10, an anaerobic membrane separation mechanism 20, a second concentration mechanism 30, a pH adjustment mechanism 40, and a distillation mechanism 50.

The first concentration mechanism 10 permeates a liquid to be treated containing ammonia nitrogen, organic nitrogen, inorganic salts, and water using a first forward osmosis membrane (FO membrane). By doing so, the first forward osmosis membrane permeated liquid that has passed through the first forward osmosis membrane is separated into the first concentrated liquid that has not passed through the first forward osmosis membrane and has concentrated components contained in the liquid to be treated. It is a mechanism for

In the ammonia recovery apparatus 100 according to the present embodiment, when performing permeation treatment using the first forward osmosis membrane in the first concentration mechanism 10, the liquid to be treated is passed through the first forward osmosis membrane to the first driving solution. Transmission processing is performed while they are in contact. A solution having a higher osmotic pressure than the liquid to be treated is used as the first driving solution.

As the first driving solution, at least one selected from the group consisting of seawater, inorganic salt-dissolved water, temperature-responsive ionic liquids, and temperature-responsive polymers can be used. Note that seawater is used in this embodiment.

Concentration in the first concentration mechanism 10 is performed by a forward osmosis membrane method, which allows the liquid to be processed to be concentrated to a predetermined concentration while saving energy compared to concentration using a method that involves a phase change such as distillation. Can be done. Furthermore, by using the first driving solution as described above, efficient concentration can be performed.

Moreover, in the first concentration mechanism 10 that performs concentration using a forward osmosis membrane method, energy saving can be achieved compared to a case where concentration is performed using a reverse osmosis method using a reverse osmosis membrane.

As the first concentration mechanism 10, it is possible to use various known structures used for concentration by the forward osmosis membrane method.

In addition, as the first forward osmosis membrane used in the first concentration mechanism 10, it is possible to select and use an appropriate one from various known forward osmosis membranes in consideration of concentration conditions and the like.

In this embodiment, a liquid to be treated containing ammonia nitrogen, organic nitrogen, inorganic salts, and water is supplied to the first concentration mechanism 10 at a rate of 66.7 Ton/h. It is configured as follows.

The unprocessed liquid (66.7 Ton/h) supplied to the first concentration mechanism 10 contains 24.5 kg/h of total nitrogen (TN) derived from ammonia nitrogen and organic nitrogen; It contains 66 kg/h of total carbon (TC) and 93.3 kg/h of total dissolved solids (TDS) derived from inorganic salts.

In the first concentration mechanism 10, 54.7 T/h of the first forward osmosis membrane permeate liquid containing water as a main component that has permeated the first forward osmosis membrane and the first forward osmosis membrane permeate liquid that has not passed through the first forward osmosis membrane and is A first concentrated liquid of 12.0 tons/h in which the components dissolved in the processing liquid are concentrated is obtained.

The first forward osmosis membrane permeate of 54.7 Ton/h contains 0.5 kg/h of total nitrogen (TN) and does not contain total carbon (TC) and total dissolved solids (TDS). The first concentrate also contains 24 kg/h of total nitrogen (TN), 66 kg/h of total carbon (TC), and 93.3 kg/h of total dissolved solids (TDS).

Furthermore, when concentration is performed by the forward osmosis method using the first forward osmosis membrane in the first concentration mechanism 10, if the concentration of total nitrogen (TN) becomes too high, the anaerobic membrane separation mechanism 20, which is a subsequent process, Since the efficiency of biological treatment tends to decrease, it is desirable to suppress the concentration of total nitrogen (TN) in the liquid to be treated (first concentrated liquid) concentrated in the first concentration mechanism 10 to 3000 ppm or less.

Further, the total dissolved solids (TDS) in the liquid to be treated (first concentrated liquid) concentrated in the first concentration mechanism 10 is also desirably 15,000 ppm or less.

Note that the concentration of total nitrogen (TN) in the first concentrated liquid is 2000 ppm, and the concentration of total dissolved solids (TDS) corresponding to inorganic salts is about 7800 ppm.

In addition, the anaerobic membrane separation mechanism 20 anaerobically ferments the first concentrated liquid concentrated by the first concentration mechanism 10 using anaerobic microorganisms, thereby decomposing organic nitrogen contained in the liquid to be treated and producing methane gas. This is the mechanism for converting it into ammonia nitrogen.

Note that in the anaerobic membrane separation mechanism 20, even when the liquid to be treated contains organic compounds other than ammonia nitrogen and organic nitrogen, most of the organic compounds can be converted into methane gas. Therefore, valuable substances such as methane gas and ammonia nitrogen can be efficiently recovered.

In addition, in the case of anaerobic fermentation, the aeration required in the case of aerobic fermentation is not required, so energy consumption can be suppressed.

Note that there are no particular restrictions on the specific configuration of the anaerobic membrane separation mechanism 20, and various known configurations can be adopted.

In this embodiment, in the anaerobic membrane separation mechanism 20, the anaerobic fermentation treated liquid after anaerobic fermentation is permeated using a separation membrane having a pore size smaller than that of the anaerobic microorganisms. 0.12T/h of a microorganism-containing liquid (digested fluid) containing anaerobic microorganisms that does not pass through the separation membrane, and 11.88T/h of a separation membrane permeated liquid containing ammonia nitrogen, inorganic salts, and water that has passed through the separation membrane. h and 121 m3/h of biogas are obtained.

Note that as the separation membrane in the anaerobic membrane separation mechanism 20, various known microfiltration membranes having pore sizes smaller than those of anaerobic microorganisms can be used.

The microorganism-containing liquid (digested fluid) that does not pass through the separation membrane at 0.12 Ton/h has total nitrogen (TN) of 0.2 kg/h, total carbon (TC) of 0.35 kg/h, and total dissolved solids (TDS) of 0. Including 9kg/h.

The separation membrane permeate liquid of 11.88 Ton/h contains 23.8 kg/h of total nitrogen (TN), 0.65 kg/h of total carbon (TC), and 92.4 kg/h of total dissolved solids (TDS).

The 121 m ³ /h of biogas contains methane and carbon dioxide in a molar ratio of approximately 6:4. Note that the total amount of carbon derived from methane and carbon dioxide (total carbon TC) contained in 121 m ³ /h of biogas is 65 kg/h. ³

The second concentration mechanism 30 performs permeation treatment on the separation membrane permeate separated in the anaerobic membrane separation mechanism 20 using a second forward osmosis membrane. This mechanism separates the liquid into a second concentrated liquid that does not pass through the second forward osmosis membrane and has an increased concentration of ammonia nitrogen. Note that there is no particular restriction on the specific configuration of the second concentration mechanism 30, and various known configurations may be employed.

As the second forward osmosis membrane used in the second concentration mechanism 30, an appropriate one can be selected from a variety of known forward osmosis membranes in consideration of concentration conditions and the like.
Further, depending on the conditions, it is possible to use the same forward osmosis membrane as the first forward osmosis membrane used in the above-described first concentration mechanism 10 as the second forward osmosis membrane.

In the ammonia recovery apparatus 100 according to the present embodiment, when performing permeation treatment using the second forward osmosis membrane in the second concentration mechanism 30, the separation membrane permeate separated in the anaerobic membrane separation mechanism 20 is transferred to the second concentration mechanism 30. The permeation treatment is carried out in a state in which it is brought into contact with the second driving solution through a forward osmosis membrane. A solution having a higher osmotic pressure than the separation membrane permeate liquid separated in the anaerobic membrane separation mechanism 20 is used as the second driving solution.

As the second driving solution, at least one selected from the group consisting of seawater, inorganic salt dissolved water, temperature-responsive ionic liquid, and temperature-responsive polymer can be used.

Concentration in this second concentration mechanism 30 is also a concentration using a forward osmosis membrane method, similar to the concentration in the first concentration mechanism 10 described above, and compared to concentration by a method involving a phase change such as distillation, The liquid to be treated can be concentrated to a predetermined concentration while saving energy. Furthermore, by using the second driving solution as described above, efficient concentration can be performed.

Moreover, in the second concentration mechanism 30 that performs concentration using a forward osmosis membrane method, energy saving can be achieved compared to a case where concentration is performed using a reverse osmosis method using a reverse osmosis membrane.

The permeate that has passed through the second forward osmosis membrane (second forward osmosis membrane permeate) 9.2Ton/h contains total nitrogen (TN) 0.7kg/h, total carbon (TC) and total dissolved solids ( TDS) is not included.

In addition, the second concentrated liquid 2.68 Ton/h, which does not pass through the second forward osmosis membrane and has an increased concentration of ammonia nitrogen, has a total nitrogen (TN) of 23.1 kg/h and a total carbon (TC) of 0.65 kg. /h, including total dissolved solids (TDS) 92.4 kg/h.

In addition, in the ammonia recovery apparatus 100 according to the embodiment of the present invention, by setting the concentration of total nitrogen (TN) in the second concentrated liquid concentrated by forward osmosis in the second concentration mechanism 30 to 15000 ppm or less, the second concentration It becomes possible to perform efficient concentration by suppressing a decrease in the concentration rate (the rate at which ammonia nitrogen-containing water passes through the second forward osmosis membrane) in the concentration mechanism 30.

Note that the concentration of total nitrogen (TN) in the second concentrated solution is 8,620 ppm, and the concentration of total dissolved solids (TDS) corresponding to inorganic salts is about 34,480 ppm.

The pH adjustment mechanism 40 adjusts the pH of the second concentrated liquid concentrated by the second concentration mechanism 30 by adding alkali to liberate ammonia nitrogen so that it can be separated by distillation. It is a mechanism for

Although not particularly illustrated, the pH adjustment mechanism 40 includes a supply device (for example, a pump) for supplying an alkali (48 wt % NaOH aqueous solution in this embodiment) to the second concentrated liquid concentrated by the second concentration mechanism 30; It includes a detection device (for example, a pH meter) for detecting pH, and a control means for controlling the amount of NaOH aqueous solution supplied in conjunction with the detected pH. Note that there are no particular restrictions on the specific configuration of the pH adjustment mechanism 40.

In the ammonia recovery apparatus 100 according to the present embodiment, the pH adjustment mechanism 40 produces 0.137 Ton/h of the 48 wt% NaOH aqueous solution with respect to 2.68 Ton/h of the second concentrated liquid concentrated by the second concentration mechanism 30. is added to adjust the pH to 12.

As described above, by adjusting the pH to 12, ammonia nitrogen in the second concentrated liquid is liberated, and ammonia can be separated and recovered by distillation in the distillation mechanism 50 described later.

The second concentrated solution, 2.817 Ton/h after pH adjustment, in which 48 wt% NaOH aqueous solution was added at a rate of 0.137 Ton/h, has a total nitrogen (TN) of 23.1 kg/h and a total carbon (TC) of 0. 65 kg/h, including total dissolved solids (TDS) 130.4 kg/h.

The reason why the total dissolved solids (TDS) in the second concentrated solution after pH adjustment is higher than that in the second concentrated solution before pH adjustment is due to the addition of NaOH for pH adjustment. It is something.

In addition, in the ammonia recovery apparatus 100 of the present invention, there is no upper limit to the pH value of the second concentrated liquid supplied to the distillation mechanism 50, but usually the pH is set to about 12 to ensure that ammonia nitrogen is liberated. This allows distillation to be carried out.

In addition, the distillation mechanism 50 constituting the ammonia recovery apparatus 100 according to the present embodiment is provided with a second concentrated liquid (in this embodiment, pH adjustment is performed) which is concentrated in the second concentration mechanism 30 to increase the concentration of ammonia nitrogen. This is a mechanism that separates the second concentrated liquid (second concentrated liquid) into water, which is the bottom liquid, and distilled vapor containing ammonia at a higher concentration than the second concentrated liquid.

In this distillation mechanism 50, the second concentrated liquid that has been concentrated using a forward osmosis membrane in the second concentration mechanism 30 (i.e., ammonia is reduced to a concentration where it is not advantageous to further concentrate using a forward osmosis membrane). Since the distillation of the second concentrated liquid with an increased concentration of nitrogen is carried out, it becomes possible to use energy appropriately and recover ammonia with a high concentration.

The alkali additive liquid (second concentrated liquid after pH adjustment) is supplied to the distillation mechanism 50 at a rate of 2.817 tons/h. In addition, as mentioned above, the alkaline additive liquid (second concentrated liquid after pH adjustment) of 2.817 Ton/h contains total nitrogen (TN) of 23.1 kg/h, total carbon (TC) of 0.65 kg/h, and total Contains 130.4 kg/h of dissolved solids (TDS).

The 2.817 Ton/h alkaline additive liquid supplied to the distillation mechanism 50 is distilled in the distillation mechanism 50, and 0.038 Ton/h of distilled vapor is recovered from the top of the distillation column and the column of the distillation column. The bottoms from the bottom (water containing no ammonia nitrogen) is separated into 2.78 tons/h.

Note that 0.038 Ton/h of distilled vapor includes 23.1 kg/h of total nitrogen (TN) and does not include total carbon (TC) and total dissolved solids (TDS).

The total nitrogen (TN) in the distilled vapor is 23.1 kg/h, which is 28 kg/h in terms of NH3. Therefore, the NH3 concentration in the distilled vapor is 74 wt%.

Distilled vapor containing NH3 at a high concentration of 74 wt% can be used as is, or an absorption device is installed at the latter stage of the distillation column to absorb the NH3 with water and produce ammonia at a concentration that is easy to store at room temperature. It is also possible to form an aqueous solution.

On the other hand, 2.78 Ton/h of bottoms does not contain total nitrogen (TN), contains 0.65 kg/h of total carbon (TC), and 130.4 kg/h of total dissolved solids (TDS). This bottoms can be discharged outside the system as factory wastewater or the like without any particular water treatment or after water treatment if necessary.

As mentioned above, since NH3 is liberated in the second concentrated liquid after pH adjustment supplied to the distillation mechanism 50, it is possible to reliably separate it by distillation, and it is possible to efficiently recover ammonia. can.

In addition, in the ammonia recovery apparatus 100 according to the present embodiment, the bottoms do not contain total nitrogen (TN), but this does not have a large effect on the ammonia recovery rate and does not burden the water treatment after being discharged outside the system. Total nitrogen (TN) may be included to the extent that it does not cause any damage.
In addition, if the bottom liquid is sent to a process where there is no problem even if the bottom liquid contains total nitrogen (TN), it is acceptable for the bottom liquid to contain a certain amount of total nitrogen (TN). There are cases.

As described above, the ammonia recovery apparatus 100 according to the embodiment of the present invention includes the first concentration mechanism 10, the anaerobic membrane separation mechanism 20, the second concentration mechanism 30, the pH adjustment mechanism 40, and the distillation mechanism 50. As it has a structure that appropriately combines the following, it is possible to efficiently recover highly concentrated ammonia while achieving sufficient energy savings as a whole, and it is possible to continue stable operation. A collection device can be provided.

The present invention is not limited to the above-described embodiments, and various applications and modifications can be made within the scope of the invention.

100 Ammonia recovery device 10 First concentration mechanism 20 Anaerobic membrane separation mechanism 30 Second concentration mechanism 40 pH adjustment mechanism 50 Distillation mechanism

Claims (7)

A first forward osmosis membrane permeated liquid that has permeated the first forward osmosis membrane by permeating the liquid to be treated containing ammonia nitrogen, organic nitrogen, and water using the first forward osmosis membrane. and a first concentration mechanism that does not pass through the first forward osmosis membrane and separates the liquid into a first concentrated liquid in which the components contained in the liquid to be treated are concentrated.
The first concentrated liquid concentrated by the first concentration mechanism is subjected to anaerobic fermentation by anaerobic microorganisms, thereby decomposing the organic nitrogen and converting it into methane gas and ammonia nitrogen, and anaerobically fermenting it. A microorganism-containing liquid containing the anaerobic microorganisms that does not permeate the separation membrane by permeabilizing the subsequent anaerobic fermentation-treated liquid using a separation membrane having a pore size smaller than that of the anaerobic microorganisms; an anaerobic membrane separation mechanism that separates ammonia nitrogen that has passed through the separation membrane and a separation membrane permeate containing water;
A second forward osmosis membrane permeate that has passed through the second forward osmosis membrane by permeating the separation membrane permeate separated by the anaerobic membrane separation mechanism using a second forward osmosis membrane; a second concentration mechanism that does not pass through the second forward osmosis membrane and separates into a second concentrated liquid with an increased concentration of ammonia nitrogen;
The second concentrated liquid in which the concentration of ammonia nitrogen has been increased in the second concentration mechanism is distilled to produce a bottoms from which ammonia nitrogen has been removed, and ammonia nitrogen at a higher concentration than the second concentrated liquid. An ammonia recovery device comprising: a distillation mechanism for separating distilled vapor from distilled vapor containing distilled vapor; The ammonia recovery apparatus according to claim 1, wherein the ammonia recovery apparatus is configured so that the total nitrogen concentration in the first concentrated liquid concentrated by the first concentration mechanism is 3000 ppm or less. The ammonia recovery device according to claim 1, characterized in that the ammonia recovery device is configured such that the total nitrogen concentration in the second concentrated liquid in which the concentration of ammonia nitrogen is increased in the second concentration mechanism is 15,000 ppm or less. . In the first concentration mechanism, when performing permeation treatment using the first forward osmosis membrane, the permeation treatment is performed while the liquid to be treated is brought into contact with the first driving solution through the first forward osmosis membrane. and using a solution having a higher osmotic pressure than the liquid to be treated as the first driving solution,
In the second concentration mechanism, when performing permeation treatment using the second forward osmosis membrane, the permeation treatment is performed while the separation membrane permeate is brought into contact with the second driving solution through the second forward osmosis membrane. Ammonia according to any one of claims 1 to 3, characterized in that the second driving solution is configured to use a solution having a higher osmotic pressure than the separation membrane permeate. Collection device. 5. The method according to claim 4, wherein at least one kind selected from the group consisting of seawater, inorganic salt dissolved water, temperature-responsive ionic liquid, and temperature-responsive polymer is used as the first and second driving solutions. Ammonia recovery equipment. The ammonia recovery apparatus according to claim 1, wherein the second concentrated liquid is configured to be supplied to the distillation mechanism after being pH-adjusted to be pH 9.0 or higher. The ammonia recovery apparatus according to claim 6, further comprising a pH adjustment mechanism for adjusting the pH of the second concentrated liquid.

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