JP6210883B2 - Operation method of waste water treatment equipment - Google Patents

Description

  The present invention relates to a method for operating a wastewater treatment apparatus. Specifically, the present invention relates to a method for operating a wastewater treatment apparatus that treats nitrogen-containing wastewater containing ammonia nitrogen by an anaerobic ammonia oxidation reaction.

  Wastewater discharged from ordinary households and business establishments may contain nitrogen components such as ammonia nitrogen, nitrite nitrogen, nitrate nitrogen, and organic nitrogen. Nitrogen-containing wastewater containing such nitrogen components leads to eutrophication of lakes, rivers, etc. and a decrease in dissolved oxygen concentration, and there is a current situation that direct drainage into the water environment is regulated. Therefore, when draining nitrogen-containing wastewater, in general, nitrogen-containing wastewater treatment is performed to oxidatively decompose or remove nitrogen components. As a method for treating low-concentration nitrogen-containing wastewater, a method of removing ionic species containing nitrogen components by ion exchange, or a method of oxidative decomposition treatment using chlorine, ozone, or the like is used. On the other hand, biological treatment using microorganisms is often adopted as a method for treating medium to high concentration nitrogen-containing wastewater.

  Conventionally, as biological treatment, oxidation reaction of ammonia nitrogen using ammonia oxidizing bacteria belonging to the genus Nitrosomonas, Nitrosococcus, Nitrosospira, Nitrosolobus, etc. In parallel with the oxidation reaction of nitrite nitrogen using nitrite-type oxidizing bacteria belonging to the genus Nitrobacter, Nitrospina, Nitrococcus, Nitrospira, etc. The mainstream is nitrification denitrification, which combines aerobic nitrification with anaerobic denitrification using heterotrophic bacteria such as Pseudomonas denitrificans.

However, in the nitrification denitrification treatment, in general, the nitrification tank for performing the aerobic nitrification treatment is treated with a nitrogen volume load of 0.2 kg-N / m ³ / day to 0.3 kg-N / m because of the treatment speed. Operate a denitrification tank that performs anaerobic denitrification in the range of about ³ / day, in a range of about 0.2 kg-N / m ³ / day to 0.4 kg-N / m ³ / day of nitrogen volume load. Is required. When general nitrogen-containing wastewater having a total nitrogen concentration of about 30 mg / L to 40 mg / L is treated with a load in this range, the nitrification tank will stay for 6 to 8 hours, and the denitrification tank for 5 to 8 hours. Since it is necessary to secure time, it is necessary to design a large-scale treatment tank according to this, and the processing format is high in equipment cost. In addition, since an organic substance such as methanol is required in the anaerobic denitrification treatment, the operation cost is also high.

Therefore, in recent years, as disclosed in Patent Document 1, development of a wastewater treatment method using an anaerobic ammonia oxidation reaction (ANAMMOX) is being promoted. The anaerobic ammonia oxidation reaction is a reaction in which ammonia is used as a hydrogen donor and nitrous acid is used as a hydrogen acceptor for denitrification at a time under anaerobic conditions, and is represented by the following reaction formula 1.
1.00NH ₄ ⁺ + 1.32NO ₂ ⁻ + 0.066HCO ₃ ⁻ + 0.13H ⁺
→ 1.02N ₂ + 0.26NO ₃ ⁻ + 0.066CH ₂ O _0.5 N _0.15 + 2.03H ₂ O (reaction formula 1)

  The anaerobic ammonia oxidation reaction is a reaction that is performed by anaerobic ammonia-oxidizing bacteria (anammox bacteria), which are autotrophic bacteria, using ammonia as a hydrogen donor. Therefore, in anaerobic denitrification treatment using this reaction, methanol is used. Thus, there is an advantage that the operation cost is reduced as compared with the conventional nitrification / denitrification treatment. Moreover, since the amount of anaerobic ammonia-oxidizing bacteria is small through wastewater treatment, it is also advantageous in that the amount of waste sludge is suppressed. On the other hand, the activity of anaerobic ammonia-oxidizing bacteria is known to be inhibited by nitrous acid, pH, various organic substances, etc., and management of appropriate treatment conditions is necessary to maintain wastewater treatment efficiency. Is done.

  For example, Non-Patent Document 1 discloses that the effect of organic compounds on anaerobic ammonia bacteria was analyzed in a batch processing test system, and the activity of anaerobic ammonia oxidizing bacteria was completely achieved at a methanol concentration of 0.5 mM. It is stated that it was lost.

  Non-Patent Document 2 also describes the inhibitory effect of methanol in a continuous treatment test system. After continuous treatment of raw water having a methanol concentration of 1.7 mM for 80 hours, the activity of anaerobic ammonia-oxidizing bacteria Was reduced to 46%.

  Furthermore, these Non-Patent Document 1 and Non-Patent Document 2 show that the activity of anaerobic ammonia-oxidizing bacteria does not recover even when the exposure to methanol is interrupted, and the inhibition of the activity by methanol is an irreversible action. It is shown.

JP 2001-037467 A

Guven D. et al., Propionate Oxidation by and Methanol Inhibition of Anaerobic Ammonium-Oxidizing Bacteria, Applied and Environmental Microbiology (2005) vol.71, No.2, p.1066-1071 K. Isaka, Y. Suwa, Y. Kimura, T. Yamagishi, T. Sumino, S. Tsuneda, Anaerobic Ammonium Oxidation (anammox) irreversibly inhibited by methanol, Applied Microbiology and Biotechnology (2008) 81, p.379-385

  As disclosed in Non-Patent Document 1 and Non-Patent Document 2, methanol, which is known to inhibit the denitrification activity of anaerobic ammonia-oxidizing bacteria, is mixed in nitrogen-containing wastewater to be treated as wastewater. It is known that it can. For example, there is an ammonia production facility as a business site that generates a large amount of nitrogen-containing wastewater, and methanol is often produced at the ammonia production facility. This is because both ammonia and methanol can be synthesized using steam reforming, and many production facilities used for these synthesis can be shared. For this reason, methanol is often mixed in the nitrogen-containing wastewater discharged from the ammonia production facility. In addition, as seen in multistage wastewater treatment facilities, a heterotrophic denitrification tank using heterotrophic bacteria and an organic matter treatment tank are placed in front of the denitrification tank that holds anaerobic ammonia-oxidizing bacteria, and the treated water from these is disposed. Introducing into the denitrification tank or arranging a heterotrophic denitrification tank after the denitrification tank and returning the treated water to the denitrification tank. For this reason, methanol added as a hydrogen donor to the denitrification tank or the organic matter treatment tank may be discharged without being utilized and may flow into the subsequent denitrification tank.

  In continuous treatment of nitrogen-containing wastewater, when high-concentration methanol flows into the denitrification tank in this way, the denitrification activity of anaerobic ammonia-oxidizing bacteria is inhibited, showing an irreversible decline, and as the continuous treatment continues The level of denitrification activity will decrease. However, anaerobic ammonia-oxidizing bacteria are known to have a long growth induction period and a very slow growth rate, and it is difficult to compensate for the reduced level of denitrification activity by the growth of bacterial cells. In addition, in order to prevent the inflow of methanol, when an organic matter treatment tank is installed in the previous stage and the organic substance treatment tank is operated so that methanol is completely decomposed, or the addition of methanol is restricted in the previous stage. Since the overall design of the wastewater treatment process is restricted, it is not preferable from the viewpoint of treatment efficiency and treatment cost. Therefore, in wastewater treatment that denitrifies nitrogen-containing wastewater with anaerobic ammonia-oxidizing bacteria, nitrogen-containing wastewater that may contain methanol can be stably maintained by maintaining the activity of anaerobic ammonia-oxidizing bacteria at a high level. There is a need for a method that can be denitrified.

  Therefore, the subject of this invention is providing the operating method of the wastewater treatment apparatus which can carry out the denitrification process stably of the nitrogen-containing wastewater containing methanol.

In order to solve the above problems, an operation method of a wastewater treatment apparatus according to the present invention is an operation method of a wastewater treatment apparatus for continuously treating nitrogen-containing wastewater containing ammonia nitrogen with anaerobic ammonia-oxidizing bacteria. The treatment apparatus comprises a concentration reducing means for reducing the methanol concentration of the nitrogen-containing wastewater, the ammonia nitrogen contained in the nitrogen-containing wastewater, and nitrite nitrogen generated by oxidation of a part of the ammonia nitrogen. A denitrification tank that converts to nitrogen gas by anaerobic ammonia-oxidizing bacteria, and the concentration reducing means, when the methanol concentration of the nitrogen-containing wastewater introduced into the denitrification tank exceeds 30 mg / L, the methanol concentration of the nitrogen-containing wastewater is reduced to less than 30 mg / L, the nitrogen-containing waste water the methanol concentration is reduced, relative to methanol Characterized in that the anaerobic ammonium oxidizing bacteria acclimatization is introduced into the denitrification tank to be maintained.

Another embodiment of the operation method of the wastewater treatment apparatus according to the present invention is an operation method of the wastewater treatment apparatus for continuously treating nitrogen-containing wastewater containing ammonia nitrogen with anaerobic ammonia oxidizing bacteria, the wastewater treatment The apparatus anaerobically supplies methanol supply means for supplying methanol to the nitrogen-containing wastewater, the ammonia nitrogen contained in the nitrogen-containing wastewater, and nitrite nitrogen generated by the partial oxidation of the ammonia nitrogen. A denitrification tank that converts the nitrogen-containing wastewater introduced into the denitrification tank to 0.5 mg / L or more and 30 mg / L or less. in methanol is supplied to the nitrogen-containing waste water, wherein the nitrogen-containing waste water the methanol is supplied, anaerobic Ann uncompleted to methanol Wherein the near-oxidizing bacteria is introduced into the denitrification tank to be maintained.

  ADVANTAGE OF THE INVENTION According to this invention, the operating method of the wastewater treatment apparatus which can denitrify the nitrogen-containing wastewater containing methanol stably can be provided.

It is the schematic which shows the example of application of the wastewater treatment apparatus which processes nitrogen-containing wastewater. It is a figure which shows schematic structure of the waste-water-treatment apparatus with which the operating method which concerns on 1st Embodiment is applied. It is a figure which shows schematic structure of the waste-water-treatment apparatus with which the operating method which concerns on 2nd Embodiment is applied. It is a figure which shows an example of schematic structure of the waste water treatment apparatus which concerns on a modification. It is a figure which shows the relationship between the methanol density | concentration of nitrogen-containing wastewater in Example 1-1, and a nitrogen removal rate. It is a figure which shows the relationship between the methanol concentration of nitrogen-containing wastewater in Example 1-2, and a nitrogen removal rate. It is a figure which shows the relationship between the methanol concentration of nitrogen-containing wastewater in Example 1-3, and a nitrogen removal rate. It is a figure which shows the relationship between the methanol density | concentration of nitrogen-containing wastewater in Comparative Example 1, and a nitrogen removal rate. It is a figure which shows the relationship between the methanol density | concentration of nitrogen-containing wastewater in Example 2-1, and a nitrogen removal rate. It is a figure which shows the relationship between the methanol density | concentration of nitrogen-containing wastewater in Example 2-2, and a nitrogen removal rate.

  Hereinafter, a method for operating a wastewater treatment apparatus according to an embodiment of the present invention will be described in detail. In addition, the same code | symbol is attached | subjected to the common part in each figure, and description about the overlapping part is abbreviate | omitted.

  The operation method of the wastewater treatment apparatus according to the present embodiment relates to an operation method of a wastewater treatment apparatus that continuously treats nitrogen-containing wastewater containing ammonia nitrogen using anaerobic ammonia oxidizing bacteria. Nitrogen-containing wastewater to be treated is generated in, for example, business sites such as ammonia production facilities, sewage treatment facilities, metal smelters, semiconductor factories, and general households, and contains ammonia nitrogen as the main nitrogen component. . Nitrogen-containing wastewater drained from business sites, etc., is pretreated in a precipitation separation tank, oil / water separation tank, other denitrification tank, organic matter treatment tank, etc., if necessary, and then denitrified by anaerobic ammonia-oxidizing bacteria To be served. In the wastewater treatment apparatus to which the operation method according to this embodiment is applied, such nitrogen-containing wastewater is continuously introduced into a denitrification tank holding anaerobic ammonia-oxidizing bacteria, and anaerobic ammonia oxidation reaction is utilized. Ammonia nitrogen is oxidized and converted to nitrogen gas.

FIG. 1 is a schematic diagram showing an application example of a wastewater treatment apparatus for treating nitrogen-containing wastewater.
As shown in FIG. 1 (a), the wastewater treatment apparatus that treats nitrogen-containing wastewater using an anaerobic ammonia oxidation reaction is divided into a nitrification tank 20 and a denitrification tank (anaerobic ammonia oxidation tank) 30, which is anaerobic. A two-tank type wastewater treatment apparatus that performs a reactive ammonia oxidation reaction is common. In the nitrification tank 20, a part of ammonia nitrogen contained in the raw water (nitrogen-containing wastewater) to be introduced is partially oxidized to nitrite nitrogen, whereby the ratio of ammonia nitrogen to nitrite nitrogen is set. The ratio is suitable for the reaction in the subsequent denitrification tank 30. In the denitrification tank 30, anaerobic ammonia oxidation reaction is performed using ammonia nitrogen as a hydrogen donor and nitrite nitrogen generated in the nitrification tank as a hydrogen acceptor, and denitrification treatment is performed using most of the nitrogen components as nitrogen gas. . Further, the remainder of the nitrogen component is drained and treated while remaining in the treated water in the form of nitrate nitrogen.

  When such a wastewater treatment apparatus is applied, an organic matter treatment tank 60 may be installed in the previous stage of the nitrification tank 20 as shown in FIG. In the organic matter treatment tank 60, the organic matter contained in the raw water is aerobically decomposed using activated sludge and the like, and a treatment for reducing the biological oxygen demand (BOD) of nitrogen-containing wastewater in advance is performed. . Moreover, as shown in FIG.1 (c), the denitrification tank (heterotrophic denitrification tank) 70 may be installed. In the heterotrophic denitrification tank 70, the nitrogen component contained in the raw water is reduced using conventional heterotrophic denitrification bacteria, and the treated water in the nitrification tank 20 and the denitrification tank 30 is returned as necessary. The process which reduces the nitrogen component density | concentration of nitrogen-containing wastewater by doing is performed. Further, the heterotrophic denitrification tank 70 may be installed in the subsequent stage of the denitrification tank (anaerobic ammonia oxidation tank) 30 as shown in FIG. In the subsequent stage of the denitrification tank 30, reduction treatment of nitrate nitrogen generated mainly by the anaerobic ammonia oxidation reaction is performed.

  In the continuous treatment of wastewater, the denitrification tank (anaerobic ammonia) is changed by changing the origin and dilution rate of the raw water to be treated (nitrogen-containing wastewater), the mixing ratio of raw water from multiple sources, pretreatment conditions, etc. The methanol concentration of the nitrogen-containing wastewater introduced into the (oxidation tank) 30 may fluctuate. For example, in the configuration of the wastewater treatment apparatus exemplified in FIGS. 1A, 1B, and 1D, when methanol is contained in the raw water to be treated, nitrogen-containing wastewater containing methanol is not contained. It will be introduced into the denitrification tank 30. Also in the configuration illustrated in FIG. 1B, untreated methanol is introduced into the denitrification tank 30 depending on the treatment conditions of the organic matter treatment tank 60 and the methanol concentration. Further, in the configuration of the wastewater treatment apparatus exemplified in FIGS. 1C and 1D, when methanol is added as a hydrogen donor in the heterotrophic denitrification tank 70, the added methanol remains unreacted and is subsequently It may be transferred to the denitrification tank 30 or returned to the previous stage of the denitrification tank 30. The operation method of the wastewater treatment apparatus according to this embodiment is suitably applied to wastewater treatment in which nitrogen-containing wastewater whose methanol concentration may fluctuate irregularly and indefinitely is continuously treated with anaerobic ammonia bacteria.

[First Embodiment]
First, the configuration of a wastewater treatment apparatus (wastewater treatment apparatus according to the first embodiment) to which the operation method according to the first embodiment is applied will be described.

FIG. 2 is a diagram illustrating a schematic configuration of a wastewater treatment apparatus to which the operation method according to the first embodiment is applied.
The wastewater treatment apparatus 1 according to the first embodiment is an apparatus that continuously treats nitrogen-containing wastewater containing ammonia nitrogen using anaerobic ammonia oxidizing bacteria, as a treatment tank that utilizes an anaerobic ammonia oxidation reaction. A two-tank type wastewater treatment apparatus having at least a nitrification tank and a denitrification tank. As shown in FIG. 2, the wastewater treatment apparatus 1 mainly includes an adjustment tank 10, methanol concentration measurement means 11, concentration reduction means (12 a and 12 b), a control device 16, a nitrification tank 20, and a denitrification tank 20. Nitrogen tank 30 is provided. In addition, the scale of the wastewater treatment apparatus is not particularly limited, and includes a movable apparatus that is not fixed on land and an apparatus configured with a scale corresponding to the wastewater treatment facility. Further, due to the configuration of the wastewater treatment apparatus, other treatment tanks and other preparation tanks other than those shown in FIG. 1 may be installed in the front stage, the intermediate stage, or the rear stage.

  In the wastewater treatment apparatus 1, nitrogen-containing wastewater to be treated is introduced from a wastewater supply source (not shown). Examples of the wastewater supply source include a storage tank for temporarily storing wastewater, a heterotrophic denitrification tank using heterotrophic denitrification bacteria, a sulfur denitrification tank using sulfur oxidative denitrification bacteria, and other various organic substances, sulfides, Examples include a treatment tank for performing decomposition treatment of phosphorus or the like.

  A pipe drawn into the wastewater treatment apparatus 1 from a wastewater supply source (not shown) is connected to the adjustment tank 10. This pipe line is provided with, for example, a waste water supply pump (not shown) and a flow rate measuring means.

  The wastewater supply pump is an electromagnetically driven pump, a motor driven pump, or the like provided for supplying nitrogen-containing wastewater to the adjustment tank 10. The discharge amount of the wastewater supply pump is variably controlled based on the input of the control amount from the control device 16 so that the nitrogen-containing wastewater transferred from the wastewater supply source can be supplied to the adjustment tank 10 at an arbitrary flow rate.

  The flow rate measuring means is a measuring instrument or the like for measuring the flow rate of nitrogen-containing wastewater supplied to the adjustment tank 10. As the flow rate measurement means, for example, a potential measurement flow meter, a differential pressure measurement flow meter, a mass flow meter, or the like can be used. The flow rate measuring means measures the amount of nitrogen-containing wastewater transferred to the adjustment tank 10 and outputs the measurement signal to the control device 16.

  The adjusting tank 10 is a processing tank that adjusts in advance the methanol concentration of the nitrogen-containing wastewater introduced into the subsequent processing tank. As shown in FIG. 2, in the wastewater treatment apparatus 1, the adjustment tank 10 is installed in the front stage of the denitrification tank 30 and the front stage of the nitrification tank 20, and the pretreatment immediately before the denitrification tank 30 is simplified. The preparation tank 10 is mainly provided with methanol concentration measuring means 11, concentration reducing means 12a and 12b, stirring means 13 and the like.

  The methanol concentration measuring means 11 is a measuring instrument or the like for quantifying the methanol concentration of nitrogen-containing wastewater. Examples of the methanol concentration measuring unit 11 include a gas chromatograph mass spectrometer. Moreover, a total organic carbon (TOC) measuring device, a volatile organic compound (VOC) measuring device, etc. can be utilized. These measuring instruments can be used for the determination of methanol concentration of nitrogen-containing wastewater that does not substantially contain other organic components or volatile components other than methanol. The methanol concentration measuring means 11 measures the methanol concentration (or organic substance concentration substantially corresponding to the methanol concentration) of the nitrogen-containing wastewater in the adjustment tank 10 according to the sampling period of a predetermined time interval, and the measurement signal is a control device. 16 is output. In addition, such a methanol concentration measuring means can be provided in the front stage of the adjustment tank 10 so that the inlet concentration of the adjustment tank 10 is measured.

  The concentration reducing means is a device that reduces the concentration of methanol contained in the nitrogen-containing wastewater. In the wastewater treatment apparatus 1, exposure of high concentration methanol to anaerobic ammonia oxidizing bacteria is prevented by operating the concentration reducing means. For example, as shown in FIG. 2, the concentration lowering means includes a dilution water storage tank 12a for supplying dilution water to nitrogen-containing wastewater and a dilution water supply pump 12b.

  The dilution water storage tank 12a is a container that temporarily stores dilution water for diluting the nitrogen-containing wastewater. As the dilution water, for example, tap water substantially free of methanol, industrial water, industrial waste water, nitrogen-containing waste water, treated water after treatment with organic matter, and the like are used. The dilution water transferred from the water supply, industrial water supply, storage tank, etc. to the dilution water storage tank 12a is temporarily stored in the dilution water storage tank 12a, and when the concentration adjustment processing is performed, the adjustment water is supplied by the dilution water supply pump 12b. 10, the methanol concentration of waste water in the adjustment tank 10 is reduced.

  The dilution water supply pump 12b is an electromagnetically driven pump, a motor driven pump, or the like provided for supplying dilution water to the adjustment tank 10. The dilution water supply pump 12b is provided in a pipe line connecting the dilution water storage tank 12a and the adjustment tank 10. The discharge amount of the dilution water supply pump 12b is variably controlled based on the input of the control amount from the control device 16 so that the dilution water stored in the dilution water storage tank 12a can be sent to the adjustment tank 10 at an arbitrary flow rate. It has come to be. Instead of the dilution water supply pump 12b, a flow rate adjustment valve that supplies pressurized dilution water at a constant flow rate may be used.

  The stirring means 13 is a device that stirs and homogenizes the nitrogen-containing wastewater staying in the adjustment tank 10. The agitation means 13 may be any of a mechanical type based on a periodic motion of a stirring blade, a water type based on suction and discharge of nitrogen-containing wastewater, and an air flow type based on gas injection. By providing the stirring means 13, the distribution of methanol concentration of the nitrogen-containing wastewater staying in the adjustment tank 10 can be made uniform.

  The control device 16 is a device that manages the operation of the wastewater treatment device 1 and has a function of controlling a concentration adjustment process for adjusting the methanol concentration of the nitrogen-containing wastewater. The control device 16 includes, for example, an operation input unit for setting an upper limit value and a target value of the methanol concentration of the nitrogen-containing wastewater, a display unit that visualizes and displays various measurement values such as the methanol concentration of the nitrogen-containing wastewater, and various measurement means. An input unit that receives an input of a measurement signal to be output, an output unit that outputs a control signal to the concentration reduction unit, a storage unit that stores an upper limit value, a target value, various measurement values, and the like, and a control input amount to the concentration reduction unit An arithmetic unit and the like are provided. Moreover, as shown in FIG. 2, it is electrically connected to the methanol concentration measuring means 11 and the dilution water supply pump 12b via a signal line. Furthermore, a function of outputting a control signal to a wastewater supply pump or the like and a function of calculating a control input amount to the wastewater supply pump or the like may be provided.

The nitrification tank 20 is a microorganism treatment tank that uses a nitrite-type oxidizing bacterium to perform a nitrite-type oxidation reaction using ammonia as a substrate. In the nitrite-type oxidation reaction, a part of ammonia nitrogen contained in the nitrogen-containing wastewater is partially oxidized down to nitrite nitrogen, so that the nitrogen-containing wastewater used in the latter anaerobic ammonia oxidation reaction The composition is such that ammonia nitrogen and nitrite nitrogen are included in a predetermined ratio range. The nitrite-type oxidation reaction is represented by the following reaction formula 2.
NH ₄ ⁺ + 3 / 2O ₂ → NO ₂ ⁻ + 2H ⁺ + H ₂ O (reaction formula 2)

  The nitrification tank 20 holds nitrite-type oxidizing bacteria. A nitrite-type oxidizing bacterium is a bacterium that performs a nitrite-type oxidation reaction under an aerobic condition and generates nitrite ions using ammonia ions as a substrate. Specific examples include bacteria belonging to the genus Nitrobacter, the genus Nitrospina, the genus Nitrococcus, the genus Nitrospira, and the like.

  The nitrite-type oxidizing bacteria are preferably retained in the microorganism treatment tank in an immobilized state. Examples of the immobilization form include a microorganism-adhering carrier that immobilizes bacteria by adhering to the surface of the carrier, a entrapping immobilization carrier that entraps and immobilizes bacteria in the carrier, and the like.

  Examples of the carrier include gel carriers such as polyvinyl alcohol, alginic acid, polyethylene glycol, and acrylamide, plastic carriers such as cellulose, polyester, polypropylene, vinyl chloride, and polyurethane, and inorganic carriers such as activated carbon, diatomaceous earth, and zeolite. . The form of the carrier is, for example, a fluidized bed using a floating carrier molded into an appropriate shape such as a sphere, cylinder, column, cube, rectangular parallelepiped, etc. Any of fixed beds arranged in a lattice shape, a fiber shape, a chrysanthemum shape, or the like may be used. For the fluidized bed, the size of the floating carrier is preferably in the range of 1 mm to 10 mm, and the filling rate is preferably in the range of 10% by volume to 40% by volume with respect to the treatment tank capacity. On the other hand, for the fixed bed, the filling rate is preferably in the range of 10% by volume to 50% by volume in terms of the apparent occupied volume with respect to the treatment tank capacity, and the porosity is preferably 80% or more. . In FIG. 2, an immobilized microorganism 25 in which sludge containing nitrite-type oxidizing bacteria is supported on a floating carrier is held in the nitrification tank 20.

  The nitrification tank 20 is provided with aeration means 22 as shown in FIG. Further, a nitrogen component meter, a dissolved oxygen meter, a water temperature meter, a pH meter, a flow meter and the like (not shown) are provided.

  The nitrogen component meter is a measuring instrument such as a total nitrogen meter, an ammonia nitrogen meter, and a nitrite nitrogen meter that measures the concentration of the nitrogen component contained in the nitrogen-containing wastewater. The nitrogen component meter measures the total nitrogen concentration, ammonia nitrogen concentration, and nitrite nitrogen concentration contained in the nitrogen-containing wastewater. Based on the measured total nitrogen concentration and at least one of the ammonia nitrogen concentration and the nitrite nitrogen concentration, the reaction rate (nitrification rate) of the nitrite oxidation reaction is grasped.

  The aeration means 22 is a device that dissolves an oxygen-containing gas such as air in the nitrogen-containing wastewater in the nitrification tank 20. The aeration means 22 may be either an aeration type or a stirring type. The aeration means 22 dissolves the oxygen-containing gas in the nitrification tank 20, so that the inside of the nitrification tank 20 is made an aerobic atmosphere. Further, the output of the aeration means is feedback-controlled based on the measured dissolved oxygen concentration and nitrification rate, and the nitrification rate is adjusted within a predetermined range by adjusting the dissolved oxygen concentration in the nitrification tank 20. It is like that.

  The denitrification tank 30 is a microorganism treatment tank that performs anaerobic ammonia oxidation reaction using ammonia and nitrous acid as substrates using anaerobic ammonia oxidizing bacteria. In the anaerobic ammonia oxidation reaction, ammonia nitrogen contained in the nitrogen-containing wastewater is oxidized using nitrite nitrogen as a hydrogen acceptor to convert it into nitrogen gas for denitrification treatment. The anaerobic ammonia oxidation reaction is represented by the above reaction formula 1.

  The denitrification tank 30 holds anaerobic ammonia oxidizing bacteria. Anaerobic ammonia oxidizing bacteria are bacteria that perform an anaerobic ammonia oxidizing reaction under anaerobic conditions and generate nitrogen gas using ammonia and nitrous acid as substrates. Such bacteria can be obtained, for example, as a sludge-like microflora by collecting samples from lakes, rivers, soils, drained sludge, oceans, etc., and performing accumulation culture using ammonia and nitrous acid as substrates. .

  It is preferable that the anaerobic ammonia-oxidizing bacteria are retained in the microorganism treatment tank in an immobilized state. Examples of the immobilization form include, for example, a microorganism-adhering carrier that adheres and immobilizes bacteria on the carrier surface, a entrapping immobilization carrier that immobilizes and immobilizes bacteria in the carrier, and aggregates bacteria to form granules. Self-granulation and the like. The form of the carrier and its properties can be selected from those similar to those for the nitrite-type oxidizing bacteria. Further, as the nucleus for forming granules, the above-mentioned carrier, other aggregating microorganisms, and the like can be used. In FIG. 2, an immobilized microorganism 35 in which sludge containing anaerobic ammonia-oxidizing bacteria is supported on a floating carrier is held in the denitrification tank 30.

  As shown in FIG. 2, the denitrification tank 30 is provided with a stirring means. Further, a nitrogen component meter, a water temperature meter, a pH meter, a flow meter and the like (not shown) are provided.

  The nitrogen component meter is a measuring device such as a total nitrogen meter, an ammonia nitrogen meter, a nitrite nitrogen meter, or a nitrate nitrogen meter that measures the concentration of the nitrogen component contained in the nitrogen-containing wastewater. The nitrogen component meter measures the total nitrogen concentration, ammonia nitrogen concentration, nitrite nitrogen concentration, and nitrate nitrogen concentration contained in the nitrogen-containing wastewater. Based on the measured nitrogen component concentrations, the reaction rate (denitrification rate) of the anaerobic ammonia oxidation reaction and the nitrogen removal rate through wastewater treatment are grasped.

  The stirring means 33 is a device that stirs and homogenizes the nitrogen-containing wastewater staying in the denitrification tank 30. The agitation means 33 may be any of a mechanical type based on a periodic motion of a stirring blade, a water type based on suction and discharge of nitrogen-containing wastewater, and an air flow type based on oxygen-free gas injection. By providing the agitation means 33, the nitrogen-containing wastewater staying in the denitrification tank 30 can be agitated and the level of the denitrification rate can be maintained without aeration of the oxygen-containing gas.

  A nitrate nitrogen treatment tank, a sludge recovery tank, etc. (not shown) are installed at the subsequent stage of the denitrification tank 30 as necessary, and the treated water of the wastewater treatment apparatus 1 is drained. The nitrate nitrogen treatment tank includes, for example, a microbial treatment tank that reduces nitrate nitrogen to nitrogen gas for treatment, a chemical treatment tank that includes an ion exchange membrane, a reverse osmosis membrane, a denitration catalyst, and the like. In the sludge collection tank, sludge containing anaerobic ammonia-oxidizing bacteria and the like flowing out from the denitrification tank is filtered and collected.

  Next, a method for operating the wastewater treatment apparatus according to the first embodiment will be described.

  The operation method of the wastewater treatment apparatus according to the first embodiment is an operation method of the wastewater treatment apparatus 1 including the concentration reducing means 12a and 12b and the denitrification tank 30, and the nitrogen reduction is performed by the concentration reducing means 12a and 12b. This is a method of performing a concentration adjustment process for reducing the methanol concentration of wastewater. The concentration adjustment process is performed by reducing the methanol concentration of the nitrogen-containing wastewater to 30 mg / L or less when the methanol concentration of the nitrogen-containing wastewater introduced into the denitrification tank 30 exceeds 30 mg / L. Note that the decrease in methanol concentration is due to dilution of the nitrogen-containing wastewater.

  The methanol concentration of 30 mg / L is a critical concentration that the present inventors have found in a continuous treatment system of waste water, and in the continuous treatment system, an irreversible decrease in the denitrification activity exhibited by anaerobic ammonia oxidizing bacteria. The maximum allowable concentration of methanol that does not appear and is acceptable to maintain the level of denitrification activity. That is, in the continuous treatment system, when the methanol concentration in the nitrogen-containing wastewater exceeds 30 mg / L (inhibition concentration), the influence of inhibition by methanol appears, and the nitrogen removal rate in the wastewater treatment apparatus tends to decrease. When the inflow of excess nitrogen-containing wastewater continues, the reduction of the nitrogen removal rate further proceeds. On the other hand, if the methanol concentration is 30 mg / L (inhibitory concentration) or less, the denitrification activity of the bacterial flora or sludge containing anaerobic ammonia-oxidizing bacteria is difficult to inactivate, and the influence of inhibition by methanol is substantial. Has been confirmed not to be allowed.

  In the operation method of the wastewater treatment apparatus according to the first embodiment, the nitrogen concentration of the nitrogen-containing wastewater staying in the adjustment tank 10 is continuously measured during the continuous treatment of the nitrogen-containing wastewater. When the concentration of methanol exceeds 30 mg / L, the system is operated so that the concentration adjustment process by dilution is always performed. And by this density | concentration adjustment process, the nitrogen-containing wastewater which flows out from the adjustment tank 10 and is introduce | transduced into the denitrification tank 30 by reducing the methanol concentration of the nitrogen-containing wastewater which retains in the adjustment tank 10 to at least 30 mg / L or less The methanol concentration is constantly maintained at 30 mg / L or less, and exposure of methanol exceeding the inhibitory concentration against anaerobic ammonia-oxidizing bacteria held in the denitrification tank 30 is prevented.

  In the control device 16 provided in the wastewater treatment apparatus 1 according to the first embodiment, an upper limit value of the methanol concentration is set in advance by an operator input. The upper limit value directly means the maximum allowable value of the methanol concentration of the nitrogen-containing wastewater staying in the adjustment tank 10, for example, the inflow of methanol at the start of start-up operation, when the wastewater supply source is changed, etc. It is set in advance when is expected. In the wastewater treatment apparatus, the methanol concentration does not substantially increase in the nitrification tank 20 subsequent to the adjustment tank 10, and nitrogen-containing wastewater having a methanol concentration exceeding the maximum allowable concentration regulated by the adjustment tank 10 enters the denitrification tank 30. There is no inflow. Therefore, by regulating the methanol concentration in the adjustment tank 10, the methanol concentration of the nitrogen-containing wastewater introduced into the denitrification tank 30 is indirectly restricted.

  Specifically, the upper limit of the methanol concentration is an arbitrary concentration at which the methanol concentration is 30 mg / L or less, preferably an arbitrary concentration at which the methanol concentration is 0.5 mg / L or more and 30 mg / L or less, more preferably a concentration of 30 mg / L. Can be set. Accordingly, when the methanol concentration of nitrogen-containing wastewater exceeds 30 mg / L, concentration adjustment processing by dilution is always performed, and the methanol concentration of nitrogen-containing wastewater is reduced to 30 mg / L or less. . In addition, when an arbitrary concentration is 0.5 mg / L or more and 30 mg / L or less, nitrogen-containing wastewater containing a certain amount of methanol is introduced into the denitrification tank 30, and as described later, anaerobic Ammonia oxidizing bacteria can be rendered surface insensitive to methanol. In particular, when the upper limit value is set to 30 mg / L, the concentration adjustment process that dilutes the nitrogen component concentration contained in the nitrogen-containing wastewater is minimized.

  In the wastewater treatment apparatus 1 in which the upper limit value of the methanol concentration is set, nitrogen-containing wastewater that may contain methanol is introduced from a wastewater supply source. For example, the nitrogen-containing wastewater is transferred to the adjustment tank 10 at a predetermined flow rate by the wastewater supply pump while measuring the flow rate by the flow rate measuring means, and is managed so that the concentration of the nitrogen component flowing into the adjustment tank 10 gradually increases. While introducing. By managing the introduction into the adjustment tank 10 in this way, the microorganisms held in each treatment tank are acclimatized with respect to the nitrogen component, and a rapid inflow of methanol into the denitrification tank 30 is also prevented.

  In the adjustment tank 10, the methanol concentration measuring means 11 measures the methanol concentration of the nitrogen-containing wastewater. The methanol concentration measuring means 11 measures the methanol concentration of the nitrogen-containing wastewater staying in the adjustment tank 10 according to a sampling period of a predetermined time interval, and outputs a measurement signal of the measured methanol concentration to the control device 16. The measured methanol concentration is not necessarily limited to the concentration of methanol itself, and if the nitrogen-containing wastewater does not substantially contain other organic components or volatile components, the amount of methanol present should be the same. It may be the total organic matter concentration or the organic matter concentration in the volatile component.

  When the control device 16 receives the methanol concentration measurement signal output from the methanol concentration measuring means 11, the control device 16 compares the measured value of the methanol concentration with a preset upper limit value of the methanol concentration, and the measured value of the methanol concentration. If the value exceeds the upper limit value, a concentration adjustment process by dilution is performed. That is, the control amount of the dilution water supply pump 12b is calculated based on the deviation between the measured value and the upper limit value, and a control signal of the calculated control amount is output to the dilution water supply pump 12b. And the dilution water supply pump 12b which received the input of the control signal changes the discharge amount of dilution water by the normal operation based on the control amount calculated by the control device 16, and the dilution stored in the dilution water storage tank 12a. Water is supplied to the adjustment tank 10 at a predetermined flow rate.

  In the concentration adjustment process, the amount of nitrogen-containing wastewater transferred to the adjustment tank 10 is adjusted along with the adjustment of the supply amount of diluted water based on the measured value of the amount of nitrogen-containing wastewater measured by a flow rate measuring means (not shown). May be. For example, the outlet flow rate of the adjustment tank 10 is obtained based on the supply amount of dilution water expected to be supplied to the adjustment tank 10 and the latest value of the flow rate value of the nitrogen-containing wastewater stored in the control device 16. Accordingly, it is possible to adjust the amount of nitrogen-containing wastewater transferred to the adjustment tank 10 and to set the supply amount of dilution water. Thereby, it is possible to prevent the occurrence of overflow due to the supply of a large amount of dilution water. Further, the concentration adjustment processing may be based on an integrated value of concentration displacement during a predetermined measurement interval, or may be performed by a method of controlling the valve opening degree of the concentration reducing means in a time division manner. Based on the measured value measured by the other methanol concentration measuring means installed in the preceding stage of the adjustment tank 10, the control amount of the feedforward control is calculated, and the controlled variable is corrected with the measured value measured by the methanol concentration measuring means 11. You may control to do. These control parameters are obtained, for example, in a pre-test set to the same processing conditions.

  On the other hand, the control device 16 compares the measured value of the methanol concentration with a preset upper limit value of the methanol concentration, and if the measured value of the methanol concentration is less than or equal to the upper limit value, the concentration adjustment by dilution is performed. No processing is performed. In this case, the dilution water supply pump 12b is kept in a fully closed state, the supply of nitrogen-containing waste water to the adjustment tank is continued by the waste water supply pump, and the methanol concentration of the nitrogen-containing waste water staying in the adjustment tank 10 increases again. Until then, the dilution water is not substantially supplied to the adjustment tank 10.

  As described above, in the adjustment tank 10, the nitrogen-containing wastewater introduced into the subsequent denitrification tank 30 by performing feedback control of the operation of the dilution water supply pump 12 b in accordance with the change in the methanol concentration of the nitrogen-containing wastewater that remains. The methanol concentration is reduced to at least 30 mg / L or less. Thereafter, the nitrogen-containing wastewater is sequentially introduced into the nitrification tank 20 and the denitrification tank 30.

  The nitrification tank 20 performs microbial treatment using a nitrite-type oxidation reaction by nitrite-oxidizing bacteria. Specifically, the microorganism treatment in the nitrification tank 20 is performed by adjusting the pH of the nitrogen-containing wastewater to about pH 6.0 to 8.5 and adjusting the water temperature to about 10 ° C. to 40 ° C. In addition, in the nitrite type oxidation reaction, alkali is reduced by consumption of ammonia nitrogen, so that alkali such as sodium hydroxide, sodium carbonate, sodium hydrogen carbonate, calcium carbonate is supplied as necessary.

  In the nitrification tank, the total nitrogen concentration, ammonia nitrogen concentration, nitrite nitrogen concentration, etc. of nitrogen-containing wastewater are measured. By measuring these nitrogen component concentrations and calculating the ratio of ammonia nitrogen concentration or nitrite nitrogen concentration to the total nitrogen concentration, the reaction rate (nitrification rate) of the nitrite oxidation reaction can be confirmed.

  The progress of the nitrite-type oxidation reaction is to oxidize part of the ammonia nitrogen contained in the nitrogen-containing wastewater to nitrite-nitrogen, so that ammonia nitrogen and nitrite nitrogen in the nitrogen-containing wastewater Is controlled so that the reaction ratio of ammonia nitrogen and nitrite nitrogen in the above reaction formula 1 (1.00: 1.32), that is, the nitrification rate is approximately 57%. The ratio of ammonia nitrogen and nitrite nitrogen can be adjusted mainly by increasing or decreasing the dissolved oxygen concentration and pH. In addition, the nitrogen-containing wastewater is distributed at a predetermined ratio in the upper stage of the nitrification tank 20, and a part thereof is flowed into the nitrification tank 20 to be subjected to microbial treatment so as to achieve a predetermined nitrification rate, while the remaining part is flowed into the nitrification tank 20. It can also be adjusted by a method of re-mixing them after detouring.

  In the denitrification tank 30, microbial treatment is performed using an anaerobic ammonia oxidation reaction by anaerobic ammonia oxidizing bacteria. Specifically, the microorganism treatment in the denitrification tank 30 is performed by adjusting the pH of the nitrogen-containing wastewater to about pH 6.0 to 8.5 and adjusting the water temperature to about 10 ° C. to 40 ° C. Further, in the anaerobic ammonia oxidation reaction, hydrogen ions are consumed, so that an acid such as sulfuric acid or hydrochloric acid is supplied as necessary.

  In the denitrification tank 30, the total nitrogen concentration, ammonia nitrogen concentration, nitrite nitrogen concentration, nitrate nitrogen concentration and the like of the nitrogen-containing wastewater are measured. By measuring the nitrogen component concentration and calculating the rate of fluctuation of the ammonia nitrogen concentration, nitrite nitrogen concentration or nitrate nitrogen concentration from the nitrification tank 20, the reaction rate of the anaerobic ammonia oxidation reaction (denitrification rate) ) Can be confirmed. Moreover, the nitrogen removal rate through wastewater treatment can be confirmed by combining with the measurement result in the previous stage.

  The progress of the anaerobic ammonia oxidation reaction in the denitrification tank 30 is preferably managed so that, for example, the outlet concentration of the nitrite nitrogen that inhibits the anaerobic ammonia oxidation reaction is lower than a predetermined concentration. Thereafter, the treated water treated in the denitrification tank 30 is subjected to nitrate nitrogen treatment as necessary, and then drained to the outside of the waste water treatment apparatus 1. The nitrate nitrogen treatment can be carried out, for example, in a microbial treatment tank that reduces nitrate nitrogen to nitrogen gas and a chemical treatment tank that includes an ion exchange membrane, a reverse osmosis membrane, a denitration catalyst, and the like. .

  In this way, the nitrogen-containing wastewater sequentially introduced into the adjustment tank 10, the nitrification tank 20, and the denitrification tank 30 is continuously processed while the concentration adjustment process for reducing the methanol concentration to be at least 30 mg / L or less is continuously performed. It will be done. In the wastewater treatment apparatus 1, when the nitrification rate, the denitrification rate, and the nitrogen removal rate with respect to the nitrogen load are stabilized, the nitrogen component concentration of the nitrogen-containing wastewater introduced into the wastewater treatment apparatus 1 is increased step by step. Even in the steady operation that reaches the load, the operation is continued so that the concentration adjustment processing is performed only when the methanol concentration of the nitrogen-containing wastewater exceeds the upper limit.

  According to the operation method of the wastewater treatment apparatus according to the first embodiment described above, the concentration reducing means 12a, 12b provided in the previous stage of the denitrification tank 30 has a methanol concentration of 30 mg / min. When the concentration exceeds L, the anaerobic ammonia-oxidizing bacteria retained in the denitrification tank 30 is always used to dilute the nitrogen-containing wastewater so that the methanol concentration of the nitrogen-containing wastewater is 30 mg / L or less. However, it is not exposed to methanol having a concentration exceeding 30 mg / L, and a decrease in the denitrification activity of anaerobic ammonia oxidizing bacteria is prevented. Therefore, it becomes possible to stably denitrify nitrogen-containing wastewater containing methanol while maintaining the denitrification activity of anaerobic ammonia-oxidizing bacteria at a high level. In addition, since the denitrification treatment can be performed stably regardless of the methanol concentration of the nitrogen-containing wastewater introduced into the wastewater treatment apparatus 1, an organic matter treatment tank such as a re-aeration tank is installed before the denitrification tank 30. However, there is an advantage that it is not necessary to operate the organic matter treatment tank so that methanol contained in the wastewater is completely decomposed. Further, when a heterotrophic denitrification tank or an organic matter treatment tank using heterotrophic bacteria is arranged in the front stage of the denitrification tank 30, there is an advantage that it is not necessary to limit the addition of methanol in them.

[Second Embodiment]
Next, a configuration of a wastewater treatment apparatus (a wastewater treatment apparatus according to the second embodiment) to which the operation method according to the second embodiment is applied will be described.

FIG. 3 is a diagram illustrating an example of a schematic configuration of a wastewater treatment apparatus to which the operation method according to the second embodiment is applied.
The wastewater treatment apparatus 2 according to the second embodiment is an apparatus that continuously treats nitrogen-containing wastewater containing ammonia nitrogen using anaerobic ammonia oxidizing bacteria, like the wastewater treatment apparatus 1 according to the first embodiment. As a treatment tank using an anaerobic ammonia oxidation reaction, this is a two-tank waste water treatment apparatus having at least a nitrification tank and a denitrification tank. The wastewater treatment apparatus 2 according to the second embodiment differs from the wastewater treatment apparatus 1 according to the first embodiment in that methanol that can inhibit the activity of anaerobic ammonia-oxidizing bacteria is treated with respect to nitrogen-containing wastewater to be treated. And methanol supply means for actively supplying. As shown in FIG. 3, the wastewater treatment apparatus 2 mainly includes an adjustment tank 10, concentration reduction means (12 a, 12 b), methanol supply means (18 a, 18 b), a control device 16, and a nitrification tank 20. And a denitrification tank 30.

  The methanol supply means is a device that increases the concentration of methanol contained in the nitrogen-containing wastewater by supplying methanol to the nitrogen-containing wastewater. In the wastewater treatment apparatus 2, the anaerobic ammonia-oxidizing bacteria are acclimatized in the nitrogen-containing wastewater containing methanol by operating the methanol supply means during the start-up operation. For example, as shown in FIG. 3, the methanol supply means includes a methanol storage tank 18a for supplying methanol to nitrogen-containing wastewater and a methanol supply pump 18b.

  The methanol storage tank 18a is a container for temporarily storing methanol to be supplied to the nitrogen-containing wastewater. As the methanol, for example, a solution diluted in advance with tap water, industrial water, nitrogen-containing waste water or the like to a predetermined concentration can be used. When the concentration adjustment process is performed, the methanol temporarily stored in the methanol storage tank 18a is supplied to the adjustment tank 10 by the methanol supply pump 18b, and the methanol concentration of the wastewater in the adjustment tank 10 is increased.

  The methanol supply pump 18b is an electromagnetic drive pump, a motor drive pump, or the like that is provided to supply methanol to the adjustment tank 10. The methanol supply pump 18 b is provided in a pipe line that connects the methanol storage tank 18 a and the adjustment tank 10. The discharge amount of the methanol supply pump 18b is variably controlled based on the input of the control amount from the control device 16 so that the methanol stored in the methanol storage tank 18a can be sent to the adjustment tank 10 at an arbitrary flow rate. It is like that. Instead of the methanol supply pump 18b, a flow rate adjusting valve that adjusts the pressurized methanol to a constant flow rate can be used.

  In the wastewater treatment apparatus 2 according to the second embodiment, by providing such methanol supply means 18a, 18b, methanol-containing wastewater containing substantially no methanol concentration or nitrogen-containing wastewater having a low methanol concentration can be used as methanol. Can be actively supplied. That is, during start-up operation, nitrogen-containing wastewater that is generally found at a low average methanol concentration (for example, 0.5 mg / L or less) or the concentration of methanol does not fluctuate irregularly or indefinitely. Stable nitrogen-containing wastewater can be used for concentration adjustment treatment.

  In the wastewater treatment apparatus 2, the control device 16 further includes an output unit that outputs a control signal to the methanol supply unit and a calculation unit that calculates a control input amount to the methanol supply unit. Moreover, as shown in FIG. 3, it is electrically connected to the methanol concentration measuring means 11 and the methanol supply means 18b via signal lines.

  Next, an operation method of the wastewater treatment apparatus according to the second embodiment will be described.

  The operation method of the wastewater treatment apparatus according to the second embodiment is the operation method of the wastewater treatment apparatus 2 including the methanol supply means 18a, 18b and the denitrification tank 30, and the nitrogen supply means 18a, 18b This is a method of performing concentration adjustment processing for increasing the methanol concentration of wastewater to a predetermined concentration. The concentration adjustment process is performed by supplying methanol to the nitrogen-containing wastewater so that the methanol concentration of the nitrogen-containing wastewater introduced into the denitrification tank 30 is 0.5 mg / L or more and 30 mg / L or less.

  The reason why methanol that inhibits the activity of anaerobic ammonia-oxidizing bacteria is intentionally supplied to the nitrogen-containing wastewater is that the anaerobic ammonia-oxidizing bacteria become insensitive to methanol on the surface by exposure to methanol at an inhibitory concentration (30 mg / L) or less. Based on the knowledge obtained by the present inventors. In a continuous treatment system, if the methanol concentration of the nitrogen-containing wastewater flowing into the denitrification tank 30 is less than or equal to the inhibitory concentration, an irreversible decrease in denitrification activity does not appear, and further, the nitrogen-containing wastewater containing such methanol It has been confirmed that the decrease in denitrification activity is reduced even if methanol having a concentration exceeding the inhibitory concentration is allowed to flow into the denitrification tank 30 after the inflow of is continued for a predetermined period. That is, under a normal nitrogen load flow rate, nitrogen-containing wastewater containing methanol in a concentration range of 0.5 mg / L or more and 30 mg / L or less is caused to flow into the denitrification tank 30 so that it is not accustomed to methanol. The aim is to impart methanol insensitivity to the anaerobic ammonia-oxidizing bacteria.

  In the operation method of the wastewater treatment apparatus according to the second embodiment, the methanol concentration of the nitrogen-containing wastewater staying in the adjustment tank 10 during the start-up operation of the wastewater treatment apparatus 2 is a predetermined concentration of 0.5 mg / L or more and 30 mg / L or less. Then, the concentration adjustment process for supplying methanol to the nitrogen-containing wastewater is performed. And by this density | concentration adjustment process, the nitrogen-containing wastewater which retains in the adjustment tank 10 is maintained in the range of 0.5 mg / L or more and 30 mg / L or less, and the nitrogen-containing which contains methanol below an inhibitory concentration Waste water is introduced into the denitrification tank 30 from the adjustment tank 10 over a predetermined period, and the anaerobic ammonia-oxidizing bacteria that are not accustomed to methanol are acclimatized in the nitrogen-containing waste water having an inhibitory concentration or less.

  In the control device 16 provided in the wastewater treatment apparatus 2 according to the second embodiment, a target value of methanol concentration is set in advance by an operator input. The target value means a control target value of the methanol concentration of the nitrogen-containing wastewater staying in the adjustment tank 10, and is set in advance at the start of the start-up operation, for example. In the wastewater treatment apparatus 2, methanol is not supplied in the nitrification tank 20 subsequent to the adjustment tank 10, and the amount of methanol deaerated by the aeration means 22 is small, so that the methanol concentration does not substantially increase or decrease. . Therefore, by adjusting the methanol concentration in the adjustment tank 10, the methanol concentration of the nitrogen-containing wastewater introduced into the denitrification tank 30 is indirectly adjusted.

  Specifically, as the target value of the methanol concentration, an arbitrary concentration at which the methanol concentration is 0.5 mg / L or more and 30 mg / L or less can be set. However, since the acclimatization period of the anaerobic ammonia oxidizing bacteria can be shortened as the concentration is higher within this concentration range, it is preferably 1 mg / L or more and 30 mg / L or less, or preferably 20 mg / L or more and 30 mg / L or less. Set an arbitrary density.

  Nitrogen-containing wastewater is introduced from a wastewater supply source into a wastewater treatment apparatus in which a target value of methanol concentration is set. For example, nitrogen-containing wastewater is transferred to a regulating tank at a predetermined flow rate by a wastewater supply pump under measurement of the flow rate by a flow rate measuring means, and introduced while managing so that the concentration of nitrogen components flowing into the regulating tank gradually increases. To do. The nitrogen-containing wastewater introduced during start-up operation is preferably wastewater that does not substantially contain methanol, or wastewater that has a low methanol concentration of 0.5 mg / L or less, and the concentration of methanol is irregular and indeterminate. Waste water that does not fluctuate and is stable at a predetermined concentration is preferable. The target value is set so as to exceed the methanol concentration of such nitrogen-containing wastewater.

  In the adjustment tank 10, the methanol concentration measuring means 11 measures the methanol concentration of the nitrogen-containing wastewater introduced. The methanol concentration measuring means 11 measures the methanol concentration of the nitrogen-containing wastewater staying in the adjustment tank 10 according to a sampling period of a predetermined time interval, and outputs a measurement signal of the measured methanol concentration to the control device 16. As in the wastewater treatment apparatus 1, the measured methanol concentration is not necessarily limited to the concentration of methanol itself.

  When the control device 16 receives the methanol concentration measurement signal output from the methanol concentration measuring means 11, the control device 16 compares the measured value of the methanol concentration with a preset target value of the methanol concentration, and measures the measured value of the methanol concentration. Is equal to or less than the target value, concentration adjustment processing by supplying methanol is performed. That is, the control amount of the methanol supply pump 18b is calculated based on the deviation between the measured value and the target value, and a control signal for the calculated control amount is output to the methanol supply pump 18b. Then, the methanol supply pump 18b that has received the input of the control signal changes the discharge amount of methanol by a normal operation based on the control amount calculated by the control device 16, and the methanol stored in the methanol storage tank 18a is flowed at a predetermined flow rate. Is supplied to the adjustment tank 10. Note that the concentration adjustment process may be performed by a method of controlling the valve opening degree of the methanol supply unit in a time division manner.

  On the other hand, the control device 16 compares the measured value of the methanol concentration with a preset target value of the methanol concentration, and if the measured value of the methanol concentration exceeds the target value, the supply of methanol is performed. Do not perform density adjustment. In this case, the methanol supply pump 18b is kept in a fully closed state, and the wastewater supply pump continues to supply the nitrogen-containing wastewater to the adjustment tank 10, and the methanol concentration of the nitrogen-containing wastewater staying in the adjustment tank 10 decreases. Until the supply of methanol is interrupted.

  As described above, in the adjustment tank 10, the methanol concentration of the nitrogen-containing wastewater introduced into the subsequent denitrification tank 30 is implemented by performing feedback control of the operation of the methanol supply pump 18 b according to the methanol concentration of the nitrogen-containing wastewater that remains. Is performed to control the concentration so that the predetermined concentration is 0.5 mg / L or more and 30 mg / L or less. Thereafter, the nitrogen-containing wastewater is sequentially introduced into the nitrification tank 20 and the denitrification tank 30.

  In the operation method according to the second embodiment, in the nitrification tank and the denitrification tank, microbial treatment is performed under conditions according to the wastewater treatment apparatus according to the first embodiment. In the start-up operation, by performing the concentration adjustment process, the methanol concentration of the nitrogen-containing wastewater introduced into the denitrification tank 30 is maintained at a predetermined concentration of 0.5 mg / L to 30 mg / L. The unfamiliar anaerobic ammonia oxidizing bacteria held in the nitrogen tank 30 are acclimatized in nitrogen-containing wastewater containing methanol at a constant concentration below the inhibition concentration without causing a decrease in denitrification activity. In the case where it is difficult to maintain the methanol concentration in the adjustment tank 10 at 30 mg / L or less only by supplying nitrogen-containing wastewater to the adjustment tank 10 by the wastewater supply pump while acclimatizing the anaerobic ammonia oxidizing bacteria. The concentration adjustment processing by dilution may be performed by the concentration reducing means 12a and 12b.

  When nitrogen-containing wastewater containing methanol in a concentration range of 0.5 mg / L or more and 30 mg / L or less is introduced over a predetermined period into a denitrification tank 30 in which unfamiliar anaerobic ammonia-oxidizing bacteria are retained, Acclimatized anaerobic ammonia oxidizing bacteria become acclimatized to methanol on the surface and become insensitive to methanol. Therefore, after starting the continuous introduction of nitrogen-containing wastewater containing methanol, after performing microbial treatment over a predetermined period, when the decrease in denitrification rate does not appear in response to the increase in methanol concentration Can finish the concentration adjustment process by supplying methanol.

  In the start-up operation, when the nitrogen component concentration of the introduced nitrogen-containing wastewater is increased stepwise and the reaction rate of each treatment tank is stabilized, steady operation is performed under a predetermined range of nitrogen load. In steady operation, the target value set in the concentration range of 0.5 mg / L or more and 30 mg / L or less can be maintained, but in the same manner as in the wastewater treatment apparatus 1, the upper limit value of the methanol concentration is input by the operator. Can also be reset. Specifically, as the upper limit value in the steady operation, an arbitrary concentration at which the methanol concentration becomes 30 mg / L or more, preferably an arbitrary concentration at which the concentration becomes 30 mg / L or more and 200 mg / L or less can be set. As a result, when the methanol concentration of the nitrogen-containing wastewater that is continuously treated fluctuates to a concentration that exceeds the upper limit value, concentration adjustment processing by dilution is performed, so that the concentration of methanol introduced into the denitrification tank 30 is excessive. Can be prevented.

  According to the operation method of the wastewater treatment apparatus according to the second embodiment described above, the methanol supply means 18a, 18b provided in the preceding stage of the denitrification tank 30 has a methanol concentration of 0. In order to perform the process of supplying methanol to the nitrogen-containing wastewater so that the concentration is 5 mg / L or more and 30 mg / L or less, anaerobic ammonia-oxidizing bacteria held in the denitrification tank 30 are exposed to methanol having a concentration exceeding 30 mg / L. It is acclimatized with nitrogen-containing wastewater containing methanol, and becomes insensitive to methanol on the surface. In general, anaerobic ammonia-oxidizing bacteria, which are known to have a long growth induction period and a very slow growth rate, are preliminarily acclimatized with methanol in this way, so that methanol is irregularly and unquantified. It is possible to stably denitrify nitrogen-containing wastewater whose concentration can be varied while maintaining the denitrification activity of anaerobic ammonia-oxidizing bacteria at a high level. Furthermore, since the conditioned anaerobic ammonia-oxidizing bacteria are not easily reduced in denitrification even when exposed to nitrogen-containing wastewater with a higher methanol concentration, the methanol concentration of the nitrogen-containing wastewater introduced into the wastewater treatment equipment varies greatly. In this case, the denitrification process can be continued stably.

[Modification]
Next, another embodiment of the wastewater treatment apparatus to which the operation method according to the above embodiment is applied (a wastewater treatment apparatus according to a modification) will be described.

FIG. 4 is a diagram illustrating an example of a schematic configuration of a wastewater treatment apparatus according to a modification.
The wastewater treatment apparatus 3 according to the modified example is a two-tank type having at least a nitrification tank and a denitrification tank as a treatment tank for performing biological treatment using an anaerobic ammonia oxidation reaction, like the wastewater treatment apparatus 2 described above. It is a wastewater treatment device. The difference between the wastewater treatment apparatus 3 according to the modified example and the wastewater treatment apparatus 2 is that the adjustment tank 10 in which the concentration adjustment process for adjusting the methanol concentration of the nitrogen-containing wastewater is performed is performed before the denitrification tank 30 and the nitrification tank 20. It is a point installed in the latter part.

  The adjustment tank 10 is a treatment tank that preliminarily adjusts the methanol concentration of the nitrogen-containing wastewater introduced into the subsequent denitrification tank 30 as in the wastewater treatment apparatus 2 described above. As shown in FIG. 4, the preparation tank 10 is mainly provided with methanol concentration measuring means 11, concentration reducing means 12a and 12b, stirring means 13, methanol supply means 18a and 18b, and the like.

  The operation method of the waste water treatment apparatus 3 according to the modification is performed according to the waste water treatment apparatuses 1 and 2 described above. That is, based on the measurement of the methanol concentration of the nitrogen-containing wastewater by the methanol concentration measuring means 11, the concentration reducing means 12a, 12b carry out concentration adjustment processing by dilution, or the methanol supply means 18a, 18b is the concentration by supplying methanol. By carrying out the adjustment process, the methanol concentration of the nitrogen-containing wastewater staying in the adjustment tank 10 is adjusted to the upper limit value or lower or the target value. The same applies to the startup and steady operation methods.

  According to the waste water treatment apparatus 3 described above, the adjustment tank 10 that performs the concentration adjustment process is installed in the front stage of the denitrification tank 30 and the rear stage of the nitrification tank 20, so that the microorganism treatment in the nitrification tank 20 is performed as described above. Nitrogen-containing wastewater that has not been subjected to concentration adjustment treatment is provided. Therefore, the nitrogen load on the nitrification tank 20 does not fluctuate due to the supply of dilution water, and the nitrite type oxidation reaction is stably maintained. Further, the supply of methanol to the nitrogen-containing wastewater has the advantage that the BOD of the nitrification tank 20 does not fluctuate, the amount of sludge generated is reduced, and the nitrite type oxidation reaction is easily stabilized.

  EXAMPLES Hereinafter, although this invention is demonstrated in detail using the Example of this invention, the technical scope of this invention is not limited to this.

  First, the influence of methanol in the continuous treatment of nitrogen-containing wastewater was evaluated in a continuous treatment test system.

  The continuous treatment test is performed by passing nitrogen-containing wastewater containing methanol through a reactor charged with anaerobic ammonia-oxidizing bacteria, and the methanol concentrations are 5 mg / L, 20 mg / L, 30 mg / L, and 40 mg / L, respectively. A total of four types of tests were performed.

  In each test, the reaction volume of the reactor was 0.5 L, and an agar-like entrapping immobilization support carrying anaerobic ammonia-oxidizing bacteria was packed at a filling rate of 20% by volume per reaction volume. The test conditions were anaerobic conditions with a water temperature of 30 ° C. and a pH of 7.6. During the continuous treatment, the pH was maintained by adding hydrochloric acid, and stirring was continued with a stirrer. The composition of synthetic wastewater used as nitrogen-containing wastewater in each test is shown in Table 1 below.

[Example 1-1]
As Example 1-1, continuous treatment of nitrogen-containing wastewater having a methanol concentration of 5 mg / L was performed. In Example 1-1, the nitrogen volume load of the wastewater flowing into the reactor is set to 4.0 kg-N / m ³ / d, and the nitrogen-containing wastewater without adding methanol is passed through. The wastewater treatment was performed over a predetermined period. Then, when the nitrogen removal rate relative to the load became stable, the nitrogen-containing wastewater to which methanol was added so as to have the composition shown in Table 1 was started to continue monitoring the nitrogen removal rate. The result is shown in FIG.

FIG. 5 is a graph showing the relationship between the methanol concentration of nitrogen-containing wastewater and the nitrogen removal rate in Example 1-1.
In FIG. 5, the horizontal axis represents the treatment time (days), the left axis represents the nitrogen volume load and nitrogen removal rate, and the right axis represents the methanol concentration of the nitrogen-containing wastewater. As shown in FIG. 5, even when the nitrogen-containing wastewater having a methanol concentration of 5 mg / L is started to pass, the nitrogen removal rate does not decrease with respect to the nitrogen load, and the nitrogen removal rate is continued while the water is passed. Was maintained.

[Example 1-2]
As Example 1-2, continuous treatment of nitrogen-containing wastewater having a methanol concentration of 20 mg / L was performed. In Example 1-2, in the same manner as in Example 1-1, the volumetric nitrogen load of wastewater flowing into the reactor was set to 4.0 kg-N / m ³ / d, and methanol was added. Nitrogen-containing wastewater without water was passed through to treat the wastewater for a predetermined period. Then, when the nitrogen removal rate relative to the load became stable, the nitrogen-containing wastewater to which methanol was added so as to have the composition shown in Table 1 was started to continue monitoring the nitrogen removal rate. The result is shown in FIG.

FIG. 6 is a diagram showing the relationship between the methanol concentration of nitrogen-containing wastewater and the nitrogen removal rate in Example 1-2.
In FIG. 6, the horizontal axis represents the treatment time (days), the left axis represents the nitrogen volume load and nitrogen removal rate, and the right axis represents the methanol concentration of the nitrogen-containing wastewater. As shown in FIG. 6, even when nitrogen-containing wastewater having a methanol concentration of 20 mg / L is passed, the nitrogen removal rate is not reduced with respect to the nitrogen load, and the nitrogen removal rate is maintained while continuing the water flow. Maintained.

[Example 1-3]
As Example 1-3, continuous treatment of nitrogen-containing wastewater having a methanol concentration of 30 mg / L was performed. In Example 1-3, in the same manner as in Example 1-1, the volumetric nitrogen load of wastewater flowing into the reactor was set to 4.0 kg-N / m ³ / d, and methanol was added. Nitrogen-containing wastewater without water was passed through to treat the wastewater for a predetermined period. Then, when the nitrogen removal rate relative to the load became stable, the nitrogen-containing wastewater to which methanol was added so as to have the composition shown in Table 1 was started to continue monitoring the nitrogen removal rate. The result is shown in FIG.

FIG. 7 is a graph showing the relationship between the methanol concentration of nitrogen-containing wastewater and the nitrogen removal rate in Example 1-3.
In FIG. 7, the horizontal axis represents the treatment time (days), the left axis represents the nitrogen volume load and nitrogen removal rate, and the right axis represents the methanol concentration of the nitrogen-containing wastewater. As shown in FIG. 7, when the nitrogen-containing wastewater having a methanol concentration of 30 mg / L was started to pass, the nitrogen removal rate with respect to the nitrogen load was slightly decreased, and was about 4.0 kg-N / m ³ / d. The nitrogen removal rate temporarily decreased by about 10% to 3.56 kg-N / m ³ / d. However, thereafter, the nitrogen removal rate showed a weak recovery tendency, and after several days, the nitrogen removal rate recovered to about 5% to about 3.81 kg-N / m ³ / d. Thereafter, the flow of nitrogen-containing wastewater containing methanol was stopped, and the flow of nitrogen-containing wastewater without adding methanol was continued. The nitrogen removal rate was 3.81 kg-N / m ³ / d. The level was maintained.

[Comparative Example 1]
As Comparative Example 1, continuous treatment of nitrogen-containing wastewater having a methanol concentration of 40 mg / L was performed. In Comparative Example 1, in the same manner as in Example 1-1, the nitrogen volume load of wastewater flowing into the reactor was set to 4.0 kg-N / m ³ / d, and methanol was not added. The nitrogen-containing wastewater was passed through to treat the wastewater over a predetermined period. Then, when the nitrogen removal rate relative to the load became stable, the nitrogen-containing wastewater to which methanol was added so as to have the composition shown in Table 1 was started to continue monitoring the nitrogen removal rate. The result is shown in FIG.

FIG. 8 is a graph showing the relationship between the methanol concentration of nitrogen-containing wastewater and the nitrogen removal rate in Comparative Example 1.
In FIG. 8, the horizontal axis represents the treatment time (days), the left axis represents the nitrogen volume load and nitrogen removal rate, and the right axis represents the methanol concentration of the nitrogen-containing wastewater. As shown in FIG. 8, when the flow of nitrogen-containing wastewater having a methanol concentration of 40 mg / L is started, the nitrogen removal rate with respect to the nitrogen load is drastically decreased and is about 3.8 kg-N / m ³ / d. The nitrogen removal rate showed a reduction of about 60% to 1.5 kg-N / m ³ / d after 3 days. Thereafter, the flow of nitrogen-containing wastewater containing methanol was stopped, and the flow of nitrogen-containing wastewater without methanol was continued, but no recovery of the nitrogen removal rate was observed.

  From these results, in the continuous treatment of nitrogen-containing wastewater, nitrogen-containing wastewater containing high-concentration methanol may suddenly flow in, or the methanol concentration of nitrogen-containing wastewater may fluctuate rapidly toward the high-concentration side. Even if it exists, if a methanol concentration exists in the range of 30 mg / L or less, it turns out that the denitrification activity of anaerobic ammonia oxidation bacteria is hard to fall. Therefore, by maintaining the methanol concentration in the range of 30 mg / L or less, the denitrification activity is maintained at a relatively high level, and it is possible to stably denitrify nitrogen-containing wastewater containing methanol. Was confirmed.

  Next, the acclimatization of the anaerobic ammonia oxidizing bacteria to the nitrogen-containing wastewater containing methanol was evaluated.

[Example 2-1]
As Example 2-1, continuous treatment of nitrogen-containing wastewater was performed while gradually increasing the methanol concentration in units of 5 mg / L. In Example 2-1, the nitrogen volume load of the wastewater flowing into the reactor is set to 4.0 kg-N / m ³ / d. First, the nitrogen-containing wastewater not added with methanol is passed through. Water treatment was continued for a predetermined period. Then, at the stage where the nitrogen removal rate with respect to the load was stabilized, the synthesis wastewater to which methanol was added so that the methanol concentration became 5 mg / L was started. After that, when the nitrogen removal rate with respect to the load is stable, the operation of passing synthetic waste water in which the methanol concentration is increased by 5 mg / L is gradually repeated until the methanol concentration finally reaches 60 mg / L. Continued monitoring. The result is shown in FIG.

FIG. 9 is a diagram showing the relationship between the methanol concentration of nitrogen-containing wastewater and the nitrogen removal rate in Example 2-1.
In FIG. 9, the horizontal axis represents the treatment time (days), the left axis represents the nitrogen volume load and nitrogen removal rate, and the right axis represents the methanol concentration of the nitrogen-containing wastewater. As shown in FIG. 9, when the methanol concentration of nitrogen-containing wastewater was increased by 5 mg / L, no decrease in nitrogen removal rate was observed, and even when the methanol concentration exceeded 30 mg / L, anaerobic ammonia The activity of oxidizing bacteria was maintained at a high level. And even in the nitrogen-containing wastewater whose methanol concentration reached 60 mg / L, a decrease in the nitrogen removal rate was not recognized, and it was confirmed that the anaerobic ammonia-oxidizing bacteria were accustomed to methanol.

[Example 2-2]
As Example 2-2, the continuous treatment of nitrogen-containing wastewater while increasing the pulse concentration so that the methanol concentration becomes high only for a predetermined period is repeated, and the change in the methanol concentration gradually increases. went. In Example 2-2, the nitrogen volume load of the wastewater flowing into the reactor is set to 4.0 kg-N / m ³ / d. First, the nitrogen-containing wastewater not added with methanol is passed through. The wastewater treatment was performed for a predetermined period of time with water. Then, at the stage where the nitrogen removal rate with respect to the load is stabilized, the passage of synthetic wastewater with a methanol concentration of 30 mg / L is started, and after a few days, the passage of synthetic wastewater with a methanol concentration of 30 mg / L is stopped. The nitrogen-containing wastewater without adding methanol was switched to water flow. Thereafter, similarly, the operation was repeated so that the methanol concentration increased to 40 mg / L, 50 mg / L, 100 mg / L, and 200 mg / L, and monitoring of the nitrogen removal rate was continued. The result is shown in FIG.

FIG. 10 is a diagram showing the relationship between the methanol concentration of nitrogen-containing wastewater and the nitrogen removal rate in Example 2-2.
In FIG. 10, the horizontal axis represents the treatment time (days), the left axis represents the nitrogen volume load and nitrogen removal rate, and the right axis represents the methanol concentration of the nitrogen-containing wastewater. As shown in FIG. 10, at the time when the synthesis wastewater having a methanol concentration of 30 mg / L was started to pass, the nitrogen removal rate with respect to the nitrogen load was slightly decreased as in Example 1-3. The nitrogen removal rate showed a recovery trend. Thereafter, even if the methanol concentration was increased to 40 mg / L, 50 mg / L, 100 mg / L, and 200 mg / L in a pulsed manner, there was no decrease in the nitrogen removal rate with respect to the load. It has been confirmed that

  From these results, as long as the anaerobic ammonia-oxidizing bacteria are acclimatized with nitrogen-containing wastewater having a methanol concentration of 30 mg / L or less, nitrogen-containing wastewater containing high-concentration methanol exceeding 30 mg / L suddenly breaks out. The denitrification activity of anaerobic ammonia-oxidizing bacteria does not decrease even if the nitrogen concentration of the nitrogen-containing wastewater increases or the methanol concentration of the nitrogen-containing wastewater fluctuates rapidly to a high concentration side exceeding 30 mg / L. It can be seen that the nitrogen-containing wastewater containing methanol can be stably denitrified while being maintained at a relatively high level.

  The denitrification activity of anaerobic ammonia-oxidizing bacteria was maintained in this way because other microorganisms mixed in the wastewater grew around the anaerobic ammonia-oxidizing bacteria to form a biofilm, and these microorganisms used methanol. It is thought that the degradation was due to the prevention of exposure of high concentration methanol to anaerobic ammonia oxidizing bacteria. Therefore, it can be said that an anaerobic ammonia-oxidizing bacterium is retained in the denitrification tank 30 in an immobilized state so that it can be easily protected by a biofilm of other microorganisms.

DESCRIPTION OF SYMBOLS 1 Waste water treatment apparatus 10 Adjustment tank 11 Methanol concentration measurement means 12a Dilution water storage tank (concentration reduction means)
12b Dilution water supply pump (concentration reducing means)
13 Stirring means 16 Control device 18a Methanol storage tank (methanol supply means)
18b Methanol supply pump (methanol supply means)
20 Nitrification tank 22 Aeration means 25 Immobilized microorganism 30 Denitrification tank 33 Stirring means 35 Immobilized microorganism 60 Organic substance treatment tank 70 Heterotrophic denitrification tank

Claims (5)

A method of operating a wastewater treatment apparatus for continuously treating nitrogen-containing wastewater containing ammonia nitrogen with anaerobic ammonia oxidizing bacteria,
The wastewater treatment device is
A concentration reducing means for reducing the methanol concentration of the nitrogen-containing wastewater;
A denitrification tank for converting the ammonia nitrogen contained in the nitrogen-containing wastewater and nitrite nitrogen generated by the oxidation of a part of the ammonia nitrogen into nitrogen gas by anaerobic ammonia oxidizing bacteria;
The concentration reducing means reduces the methanol concentration of the nitrogen-containing wastewater to 30 mg / L or less when the methanol concentration of the nitrogen-containing wastewater introduced into the denitrification tank exceeds 30 mg / L ,
The method for operating a wastewater treatment apparatus, wherein the nitrogen-containing wastewater having a reduced methanol concentration is introduced into the denitrification tank in which anaerobic ammonia-oxidizing bacteria unaccustomed to methanol are retained. . The concentration reducing means is configured to reduce the methanol concentration of the nitrogen-containing wastewater from 0.5 mg / L to 30 mg / L when the methanol concentration of the nitrogen-containing wastewater introduced into the denitrification tank exceeds 30 mg / L. The method of operating a wastewater treatment apparatus according to claim 1, wherein A method of operating a wastewater treatment apparatus for continuously treating nitrogen-containing wastewater containing ammonia nitrogen with anaerobic ammonia oxidizing bacteria,
The wastewater treatment device is
Methanol supply means for supplying methanol to the nitrogen-containing wastewater;
A denitrification tank for converting the ammonia nitrogen contained in the nitrogen-containing wastewater and nitrite nitrogen generated by the oxidation of a part of the ammonia nitrogen into nitrogen gas by anaerobic ammonia oxidizing bacteria;
The methanol supply means supplies methanol to the nitrogen-containing wastewater so that the methanol concentration of the nitrogen-containing wastewater introduced into the denitrification tank is 0.5 mg / L or more and 30 mg / L or less ,
The operation method of the wastewater treatment apparatus, wherein the nitrogen-containing wastewater supplied with the methanol is introduced into the denitrification tank in which anaerobic ammonia-oxidizing bacteria unaccustomed to methanol are retained. . The wastewater treatment apparatus further includes a concentration reducing means for reducing the methanol concentration of the nitrogen-containing wastewater,
The concentration reducing means reduces the methanol concentration of the nitrogen-containing wastewater to 30 mg / L or less when the methanol concentration of the nitrogen-containing wastewater introduced into the denitrification tank exceeds 30 mg / L. The operation method of the wastewater treatment apparatus according to claim 3 . The anaerobic ammonium oxidizing bacteria, microbial attachment carrier and secured with at least one embodiment is selected from the group consisting of entrapping immobilization pellets and autogranulated claim 1, wherein according to claim 4 The operation method of the wastewater treatment apparatus as described in any one of Claims.

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