JP4600816B2 - Method for treating ammonia-containing water - Google Patents

Description

  The present invention relates to a method for treating ammonia-containing water, and more particularly to a method for biologically denitrifying ammonia-containing water.

  Methods for biologically denitrifying ammonia-containing water are well known. The most common method oxidizes ammonia to nitrite or nitric acid by an aerobic nitrification reaction by nitrifying bacteria. Next, nitrous acid or nitric acid is converted to nitrogen gas by an anaerobic denitrification reaction by denitrifying bacteria. Since denitrifying bacteria are heterotrophic, organic matter is necessary for the denitrification reaction, and usually about three times as much organic matter as the total nitrogen concentration is added. As described above, this conventional method has been pointed out as a problem in that it requires a large amount of oxygen for the nitrification reaction and a large amount of organic matter for the denitrification reaction.

Recently, an anaerobic ammonia oxidation method has been studied in order to biologically perform denitrification treatment efficiently and inexpensively. In this method, a part of ammonia is converted into nitrous acid by the nitrification reaction shown in Chemical Formula 1, for example. Next, the remaining ammonia and the produced nitrous acid are denitrified by the reaction shown in Chemical Formula 2 by anaerobic ammonia oxidizing bacteria.

In this method, only a part of the ammonia is converted to nitrous acid, so that the amount of oxygen necessary for the nitrification reaction can be greatly reduced. Moreover, since anaerobic ammonia oxidizing bacteria are autotrophic, no organic matter is required for the denitrification reaction. For this reason, it is said that ammonia-containing water can be denitrified at low cost (see, for example, Patent Document 1 and Patent Document 2).
JP 2001-170684 A JP 2004-275997 A

  However, in the above-described anaerobic ammonia oxidation method, as shown in Chemical Formula 2, the reaction molar ratio of ammonia and nitrous acid in the denitrification reaction in the anaerobic ammonia oxidizing bacteria is 1: 1.31. Therefore, if this reaction molar ratio cannot be maintained, either ammonia or nitrous acid becomes excessive and remains in the treated water after the reaction, resulting in a reduction in treatment performance. Although Patent Document 1 and Patent Document 2 describe measures for dealing with such a technical problem, the processing is complicated and cannot be said to be a practical method.

  Even in the nitrification reaction shown in Chemical Formula 1, it is extremely difficult to uniformly convert all of ammonia into nitrous acid. In an actual nitrification reaction tank, unreacted ammonia and nitric acid are mixed in the nitrification solution in a considerable proportion. That is, if sufficient nitrification treatment is performed to reduce unreacted ammonia, nitric acid in the nitrification solution increases. Conversely, if the degree of nitrification treatment is suppressed to reduce the production of nitric acid, the amount of ammonia in the nitrification solution increases. For this reason, the balance of the above-mentioned reaction molar ratio becomes unstable, making the practical use of the anaerobic ammonia oxidation method even more difficult.

The anaerobic ammonia oxidation method is a treatment method in which nitric acid remains in the treated solution after the reaction, as apparent from Chemical Formula 2. Therefore, in order to sufficiently perform the denitrification treatment, there is a problem that the treated solution after the reaction must be further denitrified by heterotrophic denitrification bacteria, as in the conventional general method. It was.
The object of the present invention is to improve the above-mentioned problems of the prior art, do not require a large amount of oxygen and organic matter, and can be stably treated. The treated solution after the reaction is further denitrified by heterotrophic denitrifying bacteria. An object of the present invention is to provide a method for treating ammonia-containing water that does not need to be performed.

  In order to achieve the above object, the method for treating ammonia-containing water according to the present invention comprises anaerobic ammonia-oxidizing bacteria and anaerobic nitrite-oxidizing bacteria held in a denitrification tank, and the ammonia-containing water supplied to the denitrification tank, A nitrifying solution is contacted with the anaerobic ammonia oxidizing bacteria and anaerobic nitrite oxidizing bacteria under anaerobic conditions.

In the above method, the total number of anaerobic ammonia-oxidizing bacteria and anaerobic nitrite-oxidizing bacteria held in the denitrification tank is desirably 10 ⁵ cells / mL or more. Further, it is desirable that the ratio of the number of anaerobic ammonia oxidizing bacteria and anaerobic nitrite oxidizing bacteria held in the denitrification tank is 10 or less. Furthermore, it is desirable to add an organic substance to the denitrification tank so that the ratio of the amount of organic carbon added to and introduced into the denitrification tank and the total nitrogen amount is 0.1 or more.

  The anaerobic nitrite-oxidizing bacterium according to the present invention is a bacterium that was first noticed by the inventor in the course of conducting research on the nitrification and denitrification of ammonia-containing water. can do. This anaerobic nitrite-oxidizing bacterium has the same denitrification function as the anaerobic ammonia-oxidizing bacterium described in the above-mentioned section of the prior art, and is almost autotrophic. Therefore, almost no organic matter is required for the denitrification reaction. . In addition, this anaerobic nitrite-oxidizing bacterium has a function of oxidizing nitrite into nitric acid even in the absence of ammonia. In addition, it has a heterotrophic reducing action and has a function of reducing nitric acid to nitrite in the presence of organic matter.

  According to the method for treating ammonia-containing water of the present invention, since it is not necessary to nitrify the entire amount of ammonia-containing water, the amount of oxygen necessary for the nitrification reaction can be greatly reduced. Moreover, since the denitrification reaction by anaerobic ammonia oxidizing bacteria and anaerobic nitrite oxidizing bacteria in the denitrification tank is a reaction close to autotroph, a large amount of organic substances is not required. For this reason, it is possible to denitrify the ammonia-containing water at a low cost. Furthermore, in the denitrification tank, the nitric acid in the nitrifying solution flowing in and the nitric acid produced by the denitrification reaction are converted to nitrite in the presence of a small amount of organic substances by the heterotrophic reduction action of anaerobic nitrite-oxidizing bacteria. Is done. For this reason, even when the nitric acid concentration in the nitrification solution is high or when the fluctuation range of the nitric acid concentration is large, stable denitrification treatment can be performed without being particularly adversely affected. In addition, most of the nitrogen resulting from ammonia in the ammonia-containing water is converted to nitrogen gas in the denitrification tank. Therefore, the nitric acid remaining in the treated water has a very low concentration and does not need to be denitrified by heterotrophic denitrifying bacteria.

  FIG. 1 is an apparatus system diagram showing a first embodiment of a method for treating ammonia-containing water according to the present invention. A part 10 a of the ammonia-containing water 10 is supplied to the nitrification tank 12, and the remaining part 10 b is supplied to the denitrification tank 14. In the nitrification tank 12, nitrifying bacteria are held in a state of being supported on an immobilization carrier 16 or the like. In the nitrification tank 12, a part 10a of the supplied ammonia-containing water 10 comes into contact with the immobilization carrier 16 under aerobic conditions, so that the contained ammonia becomes nitrous acid or nitric acid by nitrification action by nitrifying bacteria. The nitrification liquid 18 containing nitrous acid and nitric acid treated in the nitrification tank 12 is supplied to the denitrification tank 14.

In the denitrification tank 14, anaerobic ammonia oxidizing bacteria and anaerobic nitrite oxidizing bacteria are held at a high concentration in a state where they are supported on the immobilization carrier 20. Anaerobic ammonia-oxidizing bacteria and anaerobic nitrite-oxidizing bacteria can be accumulated and cultivated from sludge in an sewage treatment plant or anaerobic nitrifying sludge. That is, anaerobic ammonia-oxidizing bacteria are prepared by adding synthetic water having a concentration ratio of ammonia nitrogen to nitrite nitrogen of about 1: 1.3 and a total nitrogen concentration of 80 mg / mL to these sludges. When anaerobic culture is carried out by continuously contacting at about N / m ³ / day, it can be cultured up to about 10 ⁷ cells / mL in about 5 months. In addition, anaerobic nitrite-oxidizing bacteria, for example, contain synthetic water having a concentration ratio of ammonia nitrogen and nitrite nitrogen of about 0.2: 1 and a total nitrogen concentration of 80 mg / mL against these sludges. When anaerobic culture is carried out by continuous contact at about −N / m ³ / day, it is possible to culture up to about 10 ⁸ cells / mL in about 3 months.

The total number of anaerobic ammonia-oxidizing bacteria and anaerobic nitrite-oxidizing bacteria held in the denitrification tank 14 is desirably 10 ⁵ cells / mL or more as will be apparent from Experiment 1 described later. The liquid phase of the denitrification tank 14 is maintained under anaerobic conditions with little oxygen, and the immobilization carrier 20 is put into a fluid state by a stirring means (not shown). The treated water 22 treated in the denitrification tank 14 is discharged from the outlet side. A screen 26 is disposed on the outlet side of the denitrification tank 14. The immobilization carrier 20 and the treated water 22 are separated by the screen 26 so that the immobilization carrier 20 does not flow out from the outlet side. The remaining portion 10b of the ammonia-containing water and the nitrification liquid 18 are vigorously mixed and contacted with the immobilized carrier 20 in a fluid state while staying in the denitrification tank 14 for a certain time.

  As a method for supporting anaerobic ammonia-oxidizing bacteria and anaerobic nitrite-oxidizing bacteria on the immobilization carrier 20, two methods of adhesion immobilization and entrapping immobilization can be used. Adhesion immobilization is a method of attaching anaerobic ammonia-oxidizing bacteria or anaerobic nitrite-oxidizing bacteria to the carrier. As the carrier, spherical, cylindrical, string-like, gel-like or non-woven fabrics are used, and as many irregularities as possible. When many materials are used, bacteria are likely to adhere and the reaction efficiency is improved. In entrapping immobilization, the bacteria and the immobilizing material (monomer, prepolymer) are mixed and then polymerized to entrapped and immobilize the bacteria inside the gel. As the monomer material, acrylamide, methylenebisacrylamide, triacryl formal and the like are preferable. The prepolymer material is preferably polyethylene glycol diacrylate or polyethylene glycol methacrylate, and derivatives thereof can be used. The shape is spherical, square, cylindrical, string-like, non-woven, and the entangled carrier with many irregularities has excellent contact efficiency and good reaction efficiency.

The immobilization carrier is not limited to one in which both anaerobic ammonia oxidizing bacteria and anaerobic nitrite oxidizing bacteria are immobilized. That is, a carrier on which anaerobic ammonia-oxidizing bacteria are immobilized and a carrier on which anaerobic nitrite-oxidizing bacteria are immobilized may be separately prepared and put into the denitrification tank 14.
The means for retaining anaerobic ammonia-oxidizing bacteria and anaerobic nitrite-oxidizing bacteria in the denitrification tank 14 is not limited to the above-described immobilization carrier, and for example, anaerobic ammonia-oxidizing bacteria and anaerobic nitrite-oxidizing bacteria are accumulated. You may make it use what made the sludge self-granulated in the shape of a granule.

  Both anaerobic ammonia oxidizing bacteria and anaerobic nitrite oxidizing bacteria have a denitrification function, and ammonia and nitrous acid are converted into nitrogen gas and nitric acid by the same reaction as shown in Chemical Formula 2 above. Since these anaerobic ammonia-oxidizing bacteria and anaerobic nitrite-oxidizing bacteria are close to autotrophs, no organic matter is required for the denitrification reaction. The ammonia in the remaining portion 10b of the ammonia-containing water 10 supplied to the denitrification tank 14 and the nitrous acid in the nitrification solution 18 are anaerobic with the anaerobic ammonia-oxidizing bacteria and anaerobic nitrite-oxidizing bacteria carried on the immobilization carrier 20. By contacting under, it is denitrified and converted to nitrogen gas and nitric acid.

  The anaerobic nitrite-oxidizing bacteria held in the denitrification tank 14 has a heterotrophic reducing action in addition to the above-described denitrification function, and has a function of reducing nitrate to nitrite in the presence of organic matter. is doing. Therefore, when moderate organic substances are present in the denitrification tank 14, the nitric acid produced by the denitrification treatment and the nitric acid contained in the nitrification solution 18 are sublimated by the reducing action of the anaerobic nitrite oxidizing bacteria. Become nitric acid. Then, since the reduced nitrous acid is repeatedly subjected to denitrification treatment, the nitric acid concentration is maintained at a very low concentration in the denitrification tank 14, and nitrogen resulting from ammonia in the ammonia-containing water 10 that is raw water Most of them are converted into nitrogen gas in the denitrification tank 14. For this reason, it is not necessary to denitrify the nitric acid remaining in the treated water 22 after the reaction by heterotrophic denitrifying bacteria.

  Note that when the ammonia-containing water or nitrification liquid flowing into the denitrification tank 14 contains almost no organic matter and the reduction action of the anaerobic nitrite oxidizing bacteria cannot be expected, an appropriate amount of the organic matter 24 is put into the denitrification tank 14. Added. Methanol, waste molasses, acetic acid, etc. are good as organic substances to be added. As will be apparent from Experiment 5 to be described later, the ratio (C / N ratio) between the amount of organic carbon added to and introduced into the denitrification tank and the total nitrogen amount is 0.1 or more, preferably 0.2 to 0.5. It is desirable to adjust the amount of organic matter added.

  As described above, according to the method for treating ammonia-containing water of the present embodiment, only a part 10a of the ammonia-containing water is introduced into the nitrification tank 12 for nitrification, so that the amount of oxygen necessary for the nitrification reaction can be greatly reduced. Further, denitrification by anaerobic ammonia-oxidizing bacteria and anaerobic nitrite-oxidizing bacteria in the denitrification tank 14 is a reaction close to autotroph, and therefore does not require a large amount of organic matter. For this reason, it is possible to denitrify the ammonia-containing water at a low cost. Furthermore, in the denitrification tank 14, nitric acid in the nitrifying solution 18 flowing in or nitric acid produced by the denitrification reaction is converted into nitrite by the heterotrophic reduction action of anaerobic nitrite oxidizing bacteria in the presence of a small amount of organic matter. Is converted to For this reason, even when the concentration of nitric acid in the nitrification solution 18 supplied from the nitrification tank 12 is high or when the fluctuation range of the concentration of nitric acid is large, stable denitrification treatment can be performed without being particularly adversely affected. Therefore, operation management of the nitrification tank 12 and the denitrification tank 14 becomes easy. In addition, most of the nitrogen resulting from ammonia in the ammonia-containing water 10 is converted into nitrogen gas in the denitrification tank 14. Therefore, the nitric acid remaining in the treated water 22 has a very low concentration and does not need to be denitrified by heterotrophic denitrifying bacteria.

2 to 8 are system diagrams showing other embodiments of the present invention. In these drawings, elements denoted by the same reference numerals as those in FIG. 1 and other drawings are substantially the same, and the description thereof is omitted.
In the second embodiment shown in FIG. 2, the nitrification tank 12 is in the rear stage, and the nitrification liquid is returned to the front-stage denitrification tank 14. The third embodiment shown in FIG. 3 is a case where the ammonia-containing water 10 contains a large amount of organic matter. A heterotrophic denitrification tank 30 is installed in the preceding stage of the denitrification tank 14, and the heterotrophic denitrification tank 30 is filled with a filler 32 in which heterotrophic denitrifying bacteria are adhered and fixed. By dispensing the nitrification liquid 18 into the heterotrophic denitrification tank 30 and the denitrification tank 14, the C / N ratio in the denitrification tank 14 is lowered to an appropriate value. The fourth embodiment shown in FIG. 4 is also a case where the ammonia-containing water 10 contains a large amount of organic matter, and the nitrification liquid 18 returned from the subsequent nitrification tank 12 is dispensed into the heterotrophic denitrification tank 30 and the denitrification tank 14. In the fifth embodiment shown in FIG. 5, floating sludge containing nitrifying bacteria and the like is circulated in the order of the denitrification tank 14, the nitrification tank 12, and the precipitation tank 34, and the precipitated sludge is returned to the denitrification tank 14 together with the nitrification liquid 18. In the sixth embodiment shown in FIG. 6, when the ammonia-containing water 10 contains a large amount of organic matter, the precipitated sludge is returned together with the nitrifying liquid 18 to the heterotrophic denitrification tank 30 and the denitrification tank 14 in the previous stage.

Experimental example Experiment 1
The activated sludge from the sewage treatment plant was used as seed sludge and included in polyethylene glycol diacrylate. This inclusive fixing body was formed into a 3 mm square to obtain an inclusive fixing carrier. The obtained carrier was filled in a culture tank having an effective volume of 1 L so that the filling rate was 20%. Synthetic water was continuously passed through the culture tank under anaerobic conditions, and anaerobic ammonia oxidizing bacteria were continuously cultured. Synthetic water has a concentration ratio of ammonia nitrogen (NH ₄ -N) and nitrite nitrogen (NO ₂ -N) of 1: 1.3 and contains 80 mg / L of total nitrogen (TN). This synthetic water was passed through the culture tank at a residence time of 6 hours (TN load 0.3 kg-N / m ³ / day). After 1 month, signs of denitrification reaction were observed, and after 5 months, it was confirmed that the denitrification reaction proceeded sufficiently and stably.

Therefore, the carrier was taken out of the culture tank and pulverized, and the pulverized carrier was used as a sample, and the number of anaerobic ammonia-oxidizing bacteria in the carrier was measured by the FISH method. That is, after the sample was dispersed by ultrasonic waves, it was stained with an AMX820 probe and directly counted with a fluorescence microscope to obtain the number of bacteria. As a result, it was found that the anaerobic ammonia oxidizing bacteria were accumulated and cultivated up to 10 ⁷ cells / mL in the finely ground carrier sample.

Experiment 2
The same entrapping immobilization support as in Experiment 1 was filled in a culture tank having an effective volume of 1 L so that the filling rate was 20%. Synthetic water was continuously passed through the culture tank under anaerobic conditions, and anaerobic nitrite oxidizing bacteria were continuously cultured. Synthetic water has a concentration ratio of ammonia nitrogen and nitrite nitrogen of about 0.2: 1 and a total nitrogen concentration of 80 mg / mL. This synthetic water was passed through with a nitrogen load of 0.3 kg-N / m ³ /. It was confirmed that nitric acid was generated in the treated water after one month, and that nitric acid in the treated water was stably progressed to almost 100% after three months.

Therefore, the carrier was taken out of the culture tank and pulverized, and the pulverized carrier was used as a sample, and the number of anaerobic nitrite oxidizing bacteria in the carrier was measured by the MPN method. In the analysis of the MPN method, a plurality of samples obtained by stepwise dilution of a finely pulverized carrier were cultured for 1 month using the medium shown in Table 1. Each sample after this culture was analyzed with an ion chromatograph, and the number of anaerobic nitrite-oxidizing bacteria in the carrier was counted by making the sample producing nitric acid positive. As a result, it was found that the anaerobic nitrite-oxidizing bacteria were accumulated and cultivated to a cell count of 10 ⁸ cells / mL in the finely ground carrier sample.

Experiment 3
Using the same finely pulverized carrier sample as in Experiment 1 and Experiment 2, a batch experiment was performed in which the total cell count was changed with a constant 1: 1 cell count ratio between anaerobic ammonia-oxidizing bacteria and anaerobic nitrite-oxidizing bacteria. Carried out. That is, in each test tube in which the total number of bacteria was changed, the TN concentration was 80 mg / L (ratio of NH ₄ -N concentration, NO ₂ -N concentration, NO ₃ -N concentration was 1: 0.5: 0. 5) A sample solution adjusted so that sodium acetate as an organic carbon source was 0.2 in terms of C / N ratio with the total nitrogen amount was injected. And each test tube was shaken in the anaerobic state, and the denitrification rate was calculated | required from the time-dependent change of TN density | concentration in a sample liquid.

FIG. 7 is a graph showing the results of a batch experiment according to Experiment 3. In FIG. 7, the horizontal axis indicates the total number of anaerobic ammonia oxidizing bacteria and anaerobic nitrite oxidizing bacteria in the sample solution, and the vertical axis indicates the denitrification rate. As is clear from FIG. 7, the denitrification rate starts to increase sharply when the total number of bacteria is 10 ⁵ cells / mL or more. From this, it can be seen that the total number of bacteria retained in the denitrification tank should be 10 ⁵ cells / mL or more in the present invention.

Experiment 4
Using the same carrier sample as in Experiment 3, the total number of anaerobic ammonia-oxidizing bacteria and anaerobic nitrite-oxidizing bacteria was a constant 10 ⁶ cells / mL, and the number of anaerobic ammonia-oxidizing bacteria and anaerobic nitrite was Batch experiments were performed with varying ratios. That is, the sample solution was injected under the same conditions as in Experiment 3 into each test tube in which the bacterial count ratio was changed. Each test tube was shaken in an anaerobic state, and the denitrification rate was determined from the change over time of the TN concentration in the sample solution.

  FIG. 8 is a graph showing the results of a batch experiment according to Experiment 4. In FIG. 8, the horizontal axis indicates the number ratio of anaerobic ammonia oxidizing bacteria and anaerobic nitrite oxidizing bacteria in the sample solution, and the vertical axis indicates the denitrification rate. As is clear from FIG. 8, when the bacteria ratio (anaerobic ammonia-oxidizing bacteria number / anaerobic nitrite-oxidizing bacteria number) exceeds 10, the denitrification rate starts to decrease rapidly. From this, it can be seen that in the present invention, the ratio of the number of anaerobic ammonia-oxidizing bacteria and anaerobic nitrite-oxidizing bacteria held in the denitrification tank may be kept to 10 or less, preferably 0.05 to 1.

Experiment 5
Using the same carrier sample as in Experiment 3, the ratio of the number of anaerobic ammonia oxidizing bacteria and anaerobic nitrite oxidizing bacteria was 0.1: 1, the total number of bacteria was 10 ⁶ cells / mL, and the C / Batch experiments were performed with varying N ratios. That is, the TN concentration as a sample solution in each test tube is constant at 80 mg / L (ratio of NH ₄ -N concentration, NO ₂ -N concentration, NO ₃ -N concentration is 1: 0.5: 0.5). Then, the one in which sodium acetate as the organic carbon source was changed in the range of 0 to 1.5 in the C / N ratio with the total nitrogen amount was injected. Each test tube was shaken in an anaerobic state for 4 hours, and then the denitrification rate was measured from the decrease in the TN concentration in the sample solution.

  FIG. 9 is a graph showing the results of a batch experiment according to Experiment 5, in which the horizontal axis represents the C / N ratio of the sample solution, and the vertical axis represents the denitrification rate. As is clear from FIG. 9, it was found that the denitrification rate was high when the C / N ratio was 0.1 or higher, and that the C / N ratio was particularly high in the range of 0.2 to 0.5. .

Experiment 6
An actual wastewater treatment experiment was conducted using the apparatus shown in FIG. The used immobilization carrier was a entrapping immobilization carrier produced with the composition shown in Table 2. As the accumulated sludge of anaerobic ammonia oxidizing bacteria and anaerobic nitrite oxidizing bacteria, the same finely ground carrier as in Experiment 1 and Experiment 2 was used. By adding potassium persulfate, the mixture having the composition shown in Table 2 is gelled. This gelled body was formed into a 3 mm square and used as a entrapping immobilization support for experiments.

The above entrapping immobilization support was charged into the denitrification tank 14 at a filling rate of 20%, and this denitrification tank 14 was tested while being mechanically stirred. The actual wastewater used had an NH ₄ —N concentration of 90 to 120 mg / L and a BOD of 15 to 30 mg / L. 60% of the actual waste water was supplied to the nitrification tank 12 and nitrified, and then sent to the denitrification tank 14 as the nitrification liquid 18 and the remaining 40% was directly supplied to the denitrification tank 14. In the denitrification tank 14, the residence time of the feed liquid was 2 hours, and no organic matter was added. The reason for not adding the organic substance is that the BOD component in the actual wastewater can be used as the organic carbon source. As a result of continuous treatment under the above conditions, a stable denitrification performance with a denitrification rate of 90% or more was exhibited after one month.

Experiment 7
Instead of the entrapping immobilization carrier in Experiment 6, the ratio of the number of anaerobic ammonia-oxidizing bacteria and anaerobic nitrite-oxidizing bacteria was 1: 1 and the total number of bacteria was 4 × 10 ⁶ cells / mL (1 1) Accumulated sludge was self-granulated, 2) Accumulated sludge adhered to and fixed on a sponge carrier was put into the denitrification tank 14, and the other conditions were the same as in Experiment 6. As a result, both (1) and (2) showed stable denitrification performance with a denitrification rate of 90% or more after one month, as with the entrapping immobilization support in Experiment 6. Thereafter, the entrapping immobilization support and (1) (2) were each subjected to high load operation by reducing the residence time of the feed liquid. In the case of the entrapping immobilization support, the denitrification rate was 12 kg-N / m ^3. / Day, in the case of (1) self-granulation, a denitrification rate of 7 kg-N / m ³ / day is obtained, and in the case of (2) the adherent fixed carrier, a denitrification rate of 5 kg-N / m ³ / day is obtained. It was. These denitrification rates were larger than the denitrification rates of the anaerobic ammonia oxidation methods that have been published so far, thus supporting the effectiveness of the method of the present invention.

1 is a system diagram showing a first embodiment of a method for treating ammonia-containing water according to the present invention. It is an apparatus system diagram which shows 2nd Embodiment of the processing method of ammonia containing water which concerns on this invention. It is an apparatus system diagram which shows 3rd Embodiment of the oxidation treatment method of the nitrous acid containing liquid which concerns on this invention. It is an apparatus system diagram which shows 4th Embodiment of the oxidation treatment method of the nitrous acid containing liquid which concerns on this invention. It is an apparatus system diagram which shows 5th Embodiment of the oxidation treatment method of the nitrous acid containing liquid which concerns on this invention. It is an apparatus system diagram which shows 8th Embodiment of the oxidation treatment method of the nitrous acid containing liquid which concerns on this invention. 10 is a graph showing an experimental result of Experiment 3. 10 is a graph showing an experimental result of Experiment 4. 10 is a graph showing an experimental result of Experiment 5.

Explanation of symbols

  10 ......... Ammonia-containing water, 12 ......... Nitrification tank, 14 ......... Denitrification tank, 18 ......... Nitrification liquid, 20 ......... Immobilized carrier, 22 ......... Treatment water, 24 ...... organic matter, 26... Screen, 30... Heterotrophic denitrification tank, 32... Filler, 34.

Claims (4)

  Anaerobic ammonia-oxidizing bacteria and anaerobic nitrite-oxidizing bacteria are held in a denitrification tank, and the anaerobic ammonia-oxidizing bacteria and anaerobic nitrite oxidation are performed under anaerobic conditions with the ammonia-containing water and nitrification solution supplied to the denitrification tank. A method for treating ammonia-containing water, which comprises contacting with bacteria. The method for treating ammonia-containing water according to claim 1, wherein the total number of anaerobic ammonia-oxidizing bacteria and anaerobic nitrite-oxidizing bacteria held in the denitrification tank is 10 ⁵ cells / mL or more.   The method for treating ammonia-containing water according to claim 1 or 2, wherein the ratio of the number of anaerobic ammonia-oxidizing bacteria and anaerobic nitrite-oxidizing bacteria held in the denitrification tank is 10 or less.   2. The ammonia-containing water according to claim 1, wherein an organic substance is added to the denitrification tank so that a ratio of an amount of organic carbon added to and introduced into the denitrification tank and a total nitrogen amount is 0.1 or more. Processing method.

Images