JP7465545B2 - Nitrite bacteria immobilized polymer gel, method for producing the nitrite bacteria immobilized polymer gel, and water treatment method - Google Patents

Description

The present invention relates to a nitrite bacteria immobilized polymer gel, a method for producing the nitrite bacteria immobilized polymer gel, and a water treatment method.

When wastewater containing nitrogen compounds flows into rivers or the ocean, it causes what is known as eutrophication of the water, and the oxygen in the water is consumed by the abnormal proliferation of microorganisms, causing the death of fish and shellfish. For this reason, it is necessary to remove nitrogen compounds from industrial wastewater, livestock wastewater, sewage, etc. to a certain level.

In wastewater treatment facilities like this, the nitrogen compounds present in the wastewater are generally removed using a biological method known as nitrification/denitrification, in which ammonia nitrogen is converted to nitrite nitrogen and nitrate nitrogen by the action of nitrifying bacteria (nitrite bacteria (ammonia oxidizing bacteria), nitrate bacteria (nitrite oxidizing bacteria)), and then converted back to nitrogen by the action of denitrifying bacteria.

In recent years, biological methods using anammox bacteria have been attracting attention (for example, Patent Documents 1 to 3). Anammox bacteria convert inorganic nitrogen compounds, such as nitrite nitrogen and ammonia nitrogen, into nitrogen gas by coupling them together. Methods using anammox bacteria are expected to significantly reduce processing costs compared to conventional nitrification-denitrification methods, as only partial nitritation is required during nitrification, so less aeration is required, and no organic matter is required for denitrification.

JP 2019-104009 A JP 2017-77509 A JP 2015-229131 A

However, in water treatment methods using anammox bacteria, while it is sufficient to oxidize roughly half of the ammoniacal nitrogen in wastewater to nitrite nitrogen, the activated sludge used in nitrification contains both nitrite and nitrate bacteria, and the nitrite nitrogen produced is soon oxidized to nitrate nitrogen by nitrate bacteria. In order to retain nitrite nitrogen, it is necessary to control the pH inside the treatment tank to a level that suppresses the activity of nitrate bacteria, which is not an easy task.

The present invention has been made in consideration of the above-mentioned circumstances, and its purpose is to provide a nitrite bacteria immobilized polymer gel that is useful in converting ammonia nitrogen to nitrite nitrogen, a method for producing the nitrite bacteria immobilized polymer gel, and a water treatment method.

The nitrite bacteria-immobilized polymer gel according to the first aspect of the present invention comprises:
Nitrite bacteria are attached to a polymer gel in which an acrylamide monomer, a methacrylamide monomer, an acrylate monomer, or a methacrylate monomer, which has an alkylene chain having two or more carbon atoms between the terminal amino group and an acrylamide group, a methacrylamide group, an acryl group, or a methacryl group, is polymerized, and a carbonate ion, a bicarbonate ion, or a hydroxide ion is added to the terminal amino group.
It is characterized by:

（式５～式８中、ｍは正の実数、ｎは２以上の整数、Ａｎ^－は炭酸イオン、重炭酸イオン又は水酸化物イオンを表す。）
ことが好ましい。 The polymer gel has a structure represented by any one of formulas 5 to 8 in a polymer main chain.

(In Formulas 5 to 8, m is a positive real number, n is an integer of 2 or more, and An ⁻ represents a carbonate ion, a bicarbonate ion, or a hydroxide ion.)
It is preferred.

It is also preferable that the polymer gel is porous.

A method for producing a nitrite bacteria-immobilized polymer gel according to a second aspect of the present invention comprises the steps of:
a polymer gel in which an acrylamide monomer, a methacrylamide monomer, an acrylate monomer or a methacrylate monomer having an alkylene chain with two or more carbon atoms between a terminal amino group and an acrylamide group, a methacrylamide group, an acryl group or a methacryl group is polymerized, and a carbonate ion, a bicarbonate ion or a hydroxide ion is added to the terminal amino group is mixed with a liquid containing nitrite bacteria, and the nitrite bacteria are cultivated inside the polymer gel;
It is characterized by:

The polymer gel may also be used, which is a copolymer of the acrylamide monomer, the methacrylamide monomer, the acrylate monomer, or the methacrylate monomer with a nonionic monomer.

A method for producing a nitrite bacteria-immobilized polymer gel according to a third aspect of the present invention comprises the steps of:
an acrylamide monomer, methacrylamide monomer, acrylate monomer or methacrylate monomer having an alkylene chain having two or more carbon atoms between a terminal amino group and an acrylamide group, methacrylamide group, acrylic group or methacryl group is polymerized in a liquid containing nitrite bacteria to obtain a nitrite bacteria immobilized polymer gel in which hydroxide ions are added to the terminal amino group and in which nitrite bacteria are attached;
It is characterized by:

The nitrite bacteria immobilized polymer gel may also be synthesized by copolymerizing the acrylamide monomer, methacrylamide monomer, acrylate monomer, or methacrylate monomer with a nonionic monomer.

A water treatment method according to a fourth aspect of the present invention comprises:
The water to be treated containing ammonia nitrogen is separated into a first water to be treated and a second water to be treated;
contacting the first treated water with the nitrite bacteria-immobilized polymer gel according to the first aspect of the present invention to convert ammonia nitrogen into nitrite nitrogen;
The first treated water, the second treated water, and anammox bacteria are contacted to generate nitrogen gas from ammonia nitrogen and nitrite nitrogen.
It is characterized by:

The present invention provides a nitrite bacteria immobilized polymer gel that is useful for converting ammonia nitrogen to nitrite nitrogen, a method for producing the nitrite bacteria immobilized polymer gel, and a water treatment method.

FIG. 2 is a diagram showing the flow of water to be treated in the water treatment method. 1 is a graph showing the internal pH of a polymer gel in an example. FIG. 3(A) is a graph showing a change in nitrite ion concentration in a solution in an example, and FIG. 3(B) is a graph showing a change in nitrate ion concentration in a solution in an example. Figures 4(A) to (C) are graphs showing the changes in ammonium ion concentration, nitrite ion concentration, nitrate ion concentration, and pH in a solution to which DMAPAA-Q gel has been added, a solution to which HCO ₃ ^-substituted DMAPAA-Q gel has been added, and a solution to which CO ₃ ^2- substituted DMAPAA-Q gel has been added, respectively. 5(A) to (C) are graphs showing the changes in ammonium ion concentration, nitrite ion concentration, nitrate ion concentration, and pH in a solution to which DMAPAA gel was added, a solution to which hydroxylamine-substituted AMPS gel was added, and a solution to which no polymer gel was added, respectively. 1 is a graph showing the internal pH in a polymer gel. 7(A) to (C) are graphs showing the NH ₄ ⁺ concentration, NO ₂ ⁻ concentration, and pH in the medium when polymer gels (G25, G75, G125, G500) were added to the medium and repeated batch culture was performed. FIG. 8(A) shows a photograph of the polymer gel after culture in which nitrite bacteria were detected by a fluorescence microscope using a nitrifying bacteria detection kit, and FIG. 8(B) shows a photograph of the polymer gel in which nitrite bacteria were detected by a fluorescence microscope using a nitrifying bacteria detection kit.

(Nitrite bacteria immobilized polymer gel and method for producing the nitrite bacteria immobilized polymer gel)
Nitrite bacteria-immobilized polymer gels are primarily used in the process of converting ammonium ions in water to nitrite ions by the action of nitrite bacteria in water treatment methods for industrial wastewater, livestock wastewater, sewage, and the like that contain ammonia nitrogen.

Nitrite bacteria immobilized polymer gel is a polymer gel in which an acrylamide monomer, methacrylamide monomer, acrylate monomer, or methacrylate monomer having an alkylene chain with two or more carbon atoms between the terminal amino group and the acrylamide group, methacrylamide group, acrylic group, or methacryl group is polymerized, and carbonate ions, bicarbonate ions, or hydroxide ions are added to the terminal amino groups, and nitrite bacteria are immobilized (held) within the internal network space of the polymer gel.

Examples of the main monomer include compounds represented by formulas 1 to 4. In formulas 1 to 4, n is an integer of 2 or more, preferably 3 to 6.

A polymer gel with hydroxide ions added can be obtained by polymerization using the main monomers represented by formula 1 and formula 2. In the polymer gel obtained by polymerization of the main monomers represented by formula 1 and formula 2, the amino groups react with water molecules in water, causing the amino groups to become protonated and hydroxide ions to be added, so a polymer gel with hydroxide ions added can be obtained simply by polymerization using these main monomers.

The protonation of the amino group in the above polymer gel occurs when the lone electron pair of the nitrogen atom of the amino group is shared by the proton (H ⁺ ). This lone electron pair is in the sp ³ hybrid orbital, and the attractive force from the nitrogen nucleus is weaker than that of the sp orbital and the sp ² hybrid orbital, so if a carbonyl group is nearby, H ⁺ easily flows into the carbonyl group. Therefore, if the length of the alkylene chain (-(CH ₂ ) _n -) is short (n = 0, 1), N is unlikely to become NH ⁺ . When n is 2 or more and the solution is acidic and abundant H ⁺ is present, H ⁺ easily acts on the nitrogen of the amino group, making it possible to protonate the amino group. Furthermore, when n is 3 or more, protonation of the amino group occurs even in a neutral solution such as water. The added hydroxide ion does not diffuse outside the polymer gel due to ionic interaction with the amino group of the ionized polymer chain (Donnan equilibrium). Therefore, the inside of the polymer gel is kept basic.

To obtain a polymer gel with carbonate ions and bicarbonate ions added, the above-mentioned polymer gel with protonated amino groups or a polymer gel with chloride ions added to amino groups obtained by polymerizing the main monomers represented by formulas 3 and 4 is placed in a liquid containing carbonate ions and bicarbonate ions. The hydroxide ions and chloride ions added to the amino groups in the polymer gel are replaced with carbonate ions and bicarbonate ions, and a polymer gel with carbonate ions and bicarbonate ions added is obtained. Alternatively, the polymer gel with protonated amino groups or the polymer gel with chloride ions added can be immersed in water and carbon dioxide gas is blown in to obtain the product.

Examples of polymer gels obtained by polymerizing the main monomers represented by the above formulas 1 to 4 and adding the various anions described above include polymer gels having skeletons represented by the formulas 5 to 8 in the polymer main chain. In the formulas, ^An- represents a hydroxide ion, a carbonate ion, or a bicarbonate ion. Furthermore, m represents a positive real number, and n has the same meaning as in the above formulas 1 to 4. The polymer gel may be polymerized using a crosslinking agent, and may be a copolymer such as a random copolymer, an alternating copolymer, or a block copolymer. In order to increase the strength of the polymer gel, a hydrophilic polymer such as polyvinyl alcohol (PVA), polyethylene glycol (PEG), or polyethyleneimine may be mixed into the monomer solution at 10 weight percent during synthesis.

In the nitrite bacteria immobilized polymer gel, nitrite bacteria are attached inside the above-mentioned polymer gel. The nitrite bacteria can be immobilized, for example, as follows. After the above-mentioned polymer gel is caused to absorb water and swell, it is placed in a liquid containing nitrite bacteria and cultured, thereby immobilizing the nitrite bacteria inside the polymer gel. Nitrite bacteria can also be immobilized inside the polymer gel by placing a dry polymer gel in activated sludge or the like containing nitrite bacteria and culturing it.

In the above-mentioned polymer gel, the internal pH is maintained at a pH that suppresses the activity of nitrate bacteria while promoting the activity of nitrite bacteria. Therefore, inside the polymer gel, the growth of nitrate bacteria is suppressed while the growth of nitrite bacteria is promoted, so that nitrite bacteria are selectively enriched and cultured inside the polymer gel, and a nitrite bacteria-immobilized polymer gel with a high concentration of nitrite bacteria attached is obtained.

Various microorganisms such as those of the Nitrosomonas and Nitrosococcus genera are known as nitrite bacteria, and liquids containing known nitrite bacteria, such as activated sludge, can be used as liquids containing nitrite bacteria. Liquids containing nitrite bacteria isolated from soil, activated sludge, etc. may also be used.

The polymer gel in which the nitrite bacteria are immobilized may be porous so that more nitrite bacteria can adhere to it. A porous polymer gel can be obtained, for example, as follows. By keeping the polymer gel synthesized as described above at -5°C or below, the water in the polymer gel freezes, and the resulting ice creates holes in the polymer gel. The polymer gel is then heated to melt the ice, resulting in a porous polymer gel. Alternatively, in the process of synthesizing the above polymer gel, the polymerization reaction can be carried out at -5°C or below, so that ice crystal formation and polymer polymerization occur simultaneously, resulting in a porous polymer gel. Using such a polymer gel, a nitrite bacteria immobilized polymer gel can be obtained, to which a large amount of nitrite bacteria are attached, by the above method.

The above describes a method for obtaining a nitrite bacteria-immobilized polymer gel in two steps: a step for synthesizing a polymer gel with hydroxide ions added, and a step for immobilizing nitrite bacteria in the polymer gel. However, in the step of synthesizing the polymer gel, a nitrite bacteria-immobilized polymer gel in which hydroxide ions are added to the amino groups at the ends and in which nitrite bacteria are attached can also be obtained by carrying out the polymerization of the main monomer represented by the above formula 1 or 2 in a liquid containing nitrite bacteria.

The nitrite bacteria immobilized polymer gel with carbonate ions and bicarbonate ions added can be obtained by placing this nitrite bacteria immobilized polymer gel with hydroxide ions added in a liquid containing carbonate ions and bicarbonate ions. It can also be obtained by polymerizing the main monomer represented by the above formula 3 or 4 in a liquid containing nitrite bacteria to synthesize a nitrite bacteria immobilized polymer gel with chloride ions added and nitrite bacteria attached, and then placing this nitrite bacteria immobilized polymer gel in a liquid containing carbonate ions and bicarbonate ions.

In addition, the blending ratio of two or more monomers may be changed and copolymerized to synthesize a polymer gel (or a nitrite bacteria immobilized polymer gel). The internal pH of the resulting polymer gel can be changed by using a non-ionic monomer and changing the blending ratio. In other words, the internal pH of the polymer gel can be adjusted, and by bringing the internal pH closer to the optimal pH for the nitrite bacteria, the activity of the nitrite bacteria can be increased and the nitrite bacteria can be enriched and cultured within the polymer gel. The non-ionic monomer may be a non-ionic acrylamide monomer, methacrylamide monomer, acrylate monomer, or methacrylate monomer, such as dimethylacrylamide or N,N-dimethylmethacrylamide.

(Water treatment method)
Next, a water treatment method using the nitrite bacteria immobilized polymer gel will be described. The water treatment method is a treatment method for removing nitrogen compounds from water containing ammonia nitrogen, such as industrial wastewater, livestock wastewater, and sewage.

Specifically, as shown in Figure 1, the flow of the water to be treated is first separated from the water to be treated that contains ammonia nitrogen.

One of the separated water streams is fed into the nitrification tank. The nitrification tank contains the above-mentioned nitrite bacteria immobilized polymer gel, and the water comes into contact with the nitrite bacteria immobilized polymer gel. Inside the nitrite bacteria immobilized polymer gel, ammonia nitrogen is converted to nitrite nitrogen by the action of the nitrite bacteria.

Next, both the treated water discharged from the nitrification tank and the treated water that does not pass through the nitrification tank are fed into the denitrification tank. Anammox bacteria are present in the denitrification tank, and ammonia nitrogen, nitrite nitrogen, and anammox bacteria come into contact with each other and are converted into nitrogen gas by the action of the anammox bacteria.

Anammox bacteria are autotrophs that obtain energy by oxidizing ammonia nitrogen with nitrite nitrogen under anaerobic conditions, so they do not require oxygen or organic matter. In addition, by using anammox bacteria, only partial nitrification is required during nitrification, which reduces the amount of oxygen consumed during nitrification.

On the other hand, in a typical nitrification process using activated sludge, nitrite and nitrate bacteria are alive, so to perform partial nitritation, pH control is required to suppress the growth of nitrate bacteria and promote the growth of nitrite bacteria. This requires a pH sensor and a pH adjuster supply device, which complicates the treatment device and leads to increased manufacturing and running costs.

In the water treatment method according to this embodiment, a nitrite bacteria immobilized polymer gel in which nitrite bacteria are attached at high concentrations inside the polymer gel is used during nitrification, so that ammonia nitrogen is only converted to nitrite nitrogen, and conversion to nitrate nitrogen is suppressed. This makes it possible to reduce the cost required for water treatment, which is extremely useful.

In addition, since anammox bacteria consume ammonia nitrogen and nitrite nitrogen in a molar ratio of approximately 1:1, it is preferable to separate the treated water in a ratio of approximately 1:1.

Aqueous solution 1 (30 mL) and Aqueous solution 2 (5 mL) shown in Table 1 were each cooled with ice water and aerated with nitrogen (30 minutes). Three types of monomers were used: DMAPAA-Q (registered trademark) ([3-(acryloylamino)propyl]trimethylaminium chloride), AMPS (2-acrylamido-2-methylpropanesulfonic acid), and DMAPAA (registered trademark) ([3-(acryloylamino)propyl]dimethylamine), and aqueous solution 1 was prepared using each monomer.

Aqueous solution 1 and aqueous solution 2 were mixed and poured into a polytetrafluoroethylene tube with an inner diameter of 6 mm. This tube was placed in a freezer at -18°C and polymerized for 24 hours. Note that within the tube, a polymer gel was synthesized by a radical polymerization reaction and freezing occurred, and the resulting ice crystals made the resulting polymer gel porous.

After the polymerization was completed, the polymer gel was removed from the tube and cut to a length of 6 mm. The resulting polymer gels are referred to as DMAPAA-Q gel, AMPS gel, and DMAPAA gel, respectively.

DMAPAA-Q gel (0.02 g) was immersed in an aqueous solution of sodium hydrogen carbonate (0.1 mol/L, 10 mL) to exchange the chloride ions added to the DMAPAA-Q gel for carbonate ions. This polymer gel is referred to as HCO ₃ ^-substituted DMAPAA-Q gel.

In addition, the DMAPAA-Q gel (0.02 g) was immersed in an aqueous sodium bicarbonate solution (0.1 mol/L, 10 mL) to exchange the chloride ions added to the DMAPAA-Q gel for bicarbonate ions. This polymer gel is referred to as CO ₃ ^2- substituted DMAPAA-Q gel.

Furthermore, AMPS gel (0.02 g) was immersed in NH ₂ OH.HCl (hydroxylamine hydrochloride) (0.1 mol/L, 10 mL) to exchange hydrogen ions for hydroxylamine. This polymer gel is referred to as hydroxylamine-substituted AMPS gel.

Then, the internal pH of each of the DMAPAA-Q gel, the DMAPAA gel, the HCO ₃ ^-substituted DMAPAA-Q gel, the CO ₃ ^2- substituted DMAPAA-Q gel, and the hydroxylamine-substituted AMPS gel was measured.

(Culture experiment)
Five types of sterilized polymer gels (DMAPAA-Q gel, DMAPAA gel, HCO ₃ ^-substituted DMAPAA-Q gel, CO ₃ ^2- substituted DMAPAA-Q gel, and hydroxylamine-substituted AMPS gel) were each placed in a baffled flask containing activated sludge (50 mL). Cultivation was carried out for three days, and the pH inside the polymer gels, and the NH ₄ ⁺ , NO ₂ ^- , and NO ₃ ^- concentrations in the solution (activated sludge) were measured.

As a control experiment, activated sludge was also cultured alone without adding the polymer gel.

The internal pH of each polymer gel is shown in Figure 2. In the polymer gels to which hydroxide ions, carbonate ions, and bicarbonate ions are respectively added (DMAPAA gel, HCO ₃ ^-substituted DMAPAA-Q gel, and CO ₃ ^2- substituted DMAPAA-Q gel), the internal pH is weakly alkaline at about 8.5 to 12, which is approximately the optimum pH for nitrite bacteria. In addition, in the DMAPAA-Q gel to which chloride ions are added, the pH is lower than the optimum pH for nitrite bacteria.

Figures 3(A) and 3(B) show the changes in NO ₂ ^- and NO ₃ ^- concentrations in the solutions to which each polymer gel was added, respectively, while Figures 4(A) to 4(C) and Figures 5(A) to 5(C) show the changes in NH ₄ ⁺ , NO ₂ ^- , NO ₃ ^- concentrations, and pH in the solutions to which each polymer gel was added.

In the hydroxylamine-substituted AMPS gel, which had the lowest pH, the NO ₂ ^- and NO ₃ ^- concentrations did not change. This indicates that the pH of the hydroxylamine-substituted AMPS gel is low, and the nitrate and nitrite bacteria that nitrify ammonia are almost inactive.

Furthermore, the DMAPAA-Q gel, which has an almost neutral internal pH, exhibits a similar NO ₂ ^- concentration to the sludge to which no polymer gel was added, and a higher NO ₃ ^- concentration than the sludge to which no polymer gel was added. This indicates that the nitrite and nitrate bacteria nitrify ammonia in the same way as the sludge, and further that the activity of the nitrate bacteria is higher than in the case of sludge alone.

Furthermore, in the DMAPAA gel, HCO ₃ ^-substituted DMAPAA-Q gel, and CO ₃ ^2- substituted DMAPAA-Q gel, in which the polymer gel pH was alkaline, the nitrite concentration was higher than in the case of sludge alone, but the nitrate concentration was lower. This indicates that the activity of nitrite bacteria was high while the activity of nitrate bacteria was low. In other words, it can be seen that in these polymer gels, the internal pH is maintained at the optimum pH for nitrite bacteria, increasing the activity of nitrite bacteria while suppressing the activity of nitrite bacteria, and the nitrite bacteria are enriched and cultured, adhering to a high concentration.

Next, the polymer gel was polymerized in a liquid containing nitrite bacteria. In addition, two types of monomers were used and the polymer gel was polymerized by changing the mixing ratio.

A monomer solution was prepared by dissolving DMAPAA (registered trademark), DMAA (registered trademark) (acryloyldimethylamine) as a monomer, methylenebisacrylamide as an accelerator, and tetraethylmethylenediamine as a crosslinking agent in 20 mL of distilled water. 100 μL of sludge was added to this monomer solution and stirred. An initiator solution in which ammonium persulfate was dissolved in 5 mL of distilled water was then added and mixed, and synthesis was carried out at a synthesis temperature of 10°C for 3 hours to produce a polymer gel with nitrite bacteria attached.

As shown in Table 2, the compounding ratio of DMAPAA (registered trademark) and DMAA (registered trademark) was changed to produce 10 types of polymer gels (G0, G25, G50, G75, G100, G125, G150, G200, G500, and G1000).

The pH inside each polymer gel in water was measured. The results are shown in Figure 6. It was found that polymer gels with different internal pHs could be obtained depending on the monomer mixing ratio.

Polymer gels (G25, G75, G125, G500) with pH values of 7.5, 8.0, 9.0, and 9.5 were added to the media with the compositions shown in Table 3, and repeated batch culture was performed at 25°C and 130 rpm with the media replaced approximately every 5 to 6 days. The pH of the media was measured over time, and the concentration of the nitrogen source in the media was measured by ion chromatography to compare the nitrification activity of the polymer gels.

The results are shown in Figures 7 (A), (B), and (C). Figure 7 (A) shows that the slope of the graph changes before and after changing the medium. By changing the medium, the nitrification rate increases, which suggests that nitrite bacteria are proliferating within the gel.

Figure 7 (B) shows that nitrite accumulation was observed in all gels. Although G500 showed a slower start of nitrification than the other gels, over time it accumulated more nitrite than the other gels. This confirms that gels with a higher internal pH are more favorable for nitrite accumulation.

Also, as shown in Figure 7 (C), as nitrification progresses, the pH of the medium drops to near the optimum pH for nitrate bacteria. However, since the accumulation of nitrite is maintained, it is believed that by immobilizing the nitrite bacteria in the polymer gel, the activity of NOB is suppressed without being significantly affected by the external pH.

In this way, it was found that a nitrite bacteria-immobilized polymer gel can be obtained by synthesizing a polymer gel in a liquid containing nitrite bacteria. It was also found that by synthesizing a polymer gel by copolymerizing the main monomers at different mixing ratios, the internal pH of the polymer gel can be brought closer to the optimal pH for nitrite bacteria.

After cultivation, the polymer gel (G500) was sliced, and a nitrifying bacteria detection kit was used to detect the bacteria on the surface of the polymer gel under a fluorescent microscope. Figures 8 (A) and (B) show photographs stained with nitrite bacteria and nitrate bacteria, respectively. It can be seen that nitrite bacteria were detected within the polymer gel, while nitrite bacteria were almost not detected. It was demonstrated that, while the activity of nitrite bacteria was suppressed within the polymer gel, the activity of nitrite bacteria was maintained at a high level, and that nitrite bacteria were enriched and cultured at a high concentration and immobilized.

It can be used to treat various types of water that contains ammonia nitrogen, such as industrial wastewater, livestock wastewater, and sewage.

Claims (8)

Nitrite bacteria are attached to a polymer gel in which an acrylamide monomer, a methacrylamide monomer, an acrylate monomer, or a methacrylate monomer, which has an alkylene chain having two or more carbon atoms between the terminal amino group and an acrylamide group, a methacrylamide group, an acryl group, or a methacryl group, is polymerized, and a carbonate ion, a bicarbonate ion, or a hydroxide ion is added to the terminal amino group.
2. A nitrite bacteria-immobilized polymer gel comprising: The polymer gel has a structure represented by any one of formulas 5 to 8 in a polymer main chain.

(In Formulas 5 to 8, m is a positive real number, n is an integer of 2 or more, and An ⁻ represents a carbonate ion, a bicarbonate ion, or a hydroxide ion.)
2. The nitrite bacteria-immobilized polymer gel according to claim 1. The polymer gel is porous.
3. The nitrite bacteria-immobilized polymer gel according to claim 1 or 2. a polymer gel in which an acrylamide monomer, a methacrylamide monomer, an acrylate monomer or a methacrylate monomer having an alkylene chain with two or more carbon atoms between a terminal amino group and an acrylamide group, a methacrylamide group, an acryl group or a methacryl group is polymerized, and a carbonate ion, a bicarbonate ion or a hydroxide ion is added to the terminal amino group is mixed with a liquid containing nitrite bacteria, and the nitrite bacteria are cultivated inside the polymer gel;
2. A method for producing a nitrite bacteria-immobilized polymer gel comprising the steps of: using the polymer gel in which the acrylamide monomer, the methacrylamide monomer, the acrylate monomer or the methacrylate monomer is copolymerized with a nonionic monomer;
The method for producing the nitrite bacteria-immobilized polymer gel according to claim 4 . an acrylamide monomer, methacrylamide monomer, acrylate monomer or methacrylate monomer having an alkylene chain having two or more carbon atoms between a terminal amino group and an acrylamide group, methacrylamide group, acrylic group or methacryl group is polymerized in a liquid in which nitrite bacteria are present, thereby obtaining a nitrite bacteria immobilized polymer gel in which hydroxide ions are added to the terminal amino group and in which nitrite bacteria are attached;
2. A method for producing a nitrite bacteria-immobilized polymer gel comprising the steps of: The acrylamide monomer, the methacrylamide monomer, the acrylate monomer or the methacrylate monomer is copolymerized with a nonionic monomer to synthesize the nitrite bacteria-immobilized polymer gel.
The method for producing the nitrite bacteria-immobilized polymer gel according to claim 6 . The water to be treated containing ammonia nitrogen is separated into a first water to be treated and a second water to be treated;
The first treated water is brought into contact with the nitrite bacteria-immobilized polymer gel according to any one of claims 1 to 3 to convert ammonia nitrogen into nitrite nitrogen;
The first treated water, the second treated water, and anammox bacteria are contacted to generate nitrogen gas from ammonia nitrogen and nitrite nitrogen.
A water treatment method comprising the steps of:

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