JP5696517B2 - Nitrite nitrogen concentration monitoring method and nitrite nitrogen concentration monitoring device - Google Patents

Description

  The present invention relates to a monitoring method and a monitoring device for nitrite nitrogen concentration in water. In particular, in the field of water treatment, the present invention relates to a nitrite nitrogen concentration monitoring method and a monitoring device used for controlling a water treatment process.

  Nitrogen is widely present in the environment and is also contained in natural water. However, the cause of the increase in nitrogen in the water that is a problem for eutrophication is due to contamination from domestic wastewater, factory wastewater, agricultural wastewater, etc. There are many. Nitrogen plays an important role in biological growth activities and is an essential element for microorganisms involved in biological treatment of wastewater. However, nitrogen is considered to be a cause of promoting eutrophication of lakes, marshes and the like, and an increase in nitrogen compounds in water is not preferable. Therefore, nitrogen removal from wastewater is performed by a method such as the biological nitrification denitrification method disclosed in Non-Patent Document 1.

The biological nitrification denitrification method will be described. First, ammonia in water is converted to nitrous acid or nitric acid by the action of nitrifying bacteria under aerobic conditions. The produced nitric acid and nitrous acid are reduced in the order of NO ₃ ⁻ → NO ₂ ⁻ → NO → N ₂ O → N ₂ and removed as nitrogen gas by the action of denitrifying bacteria.

  Regarding the control of this biological nitrification denitrification process, Non-Patent Document 1 states that “Technology for monitoring nitrification and denitrification reactions using sensors has been established to some extent for the nitrogen removal process, and technology development using this technology has been applied. The ion electrode method is mainly used as a measuring method for ammonia, and the ultraviolet absorbance method is mainly used for measuring nitric acid and nitrous acid.

  For controlling the biological nitrification / denitrification process, a control method is often used in which the end point of the nitrification / denitrification reaction is detected and the oxygen supply is turned on / off using the above-described monitoring technique.

In the nitrification process, ammonia nitrogen (NH ₄ ⁺ -N) is oxidized under aerobic conditions to nitrate nitrogen (NO ₃ ^-- N) via nitrite nitrogen (NO ₂ ^-- N). It is common. However, in order to denitrify, it is not necessary to oxidize to nitrate nitrogen, and it is sufficient to oxidize to nitrite nitrogen. This eliminates the need to supply oxygen necessary to oxidize nitrite nitrogen to nitrate nitrogen, leading to energy saving.

  However, since there is no technology that can monitor nitrite nitrogen alone in the water treatment process, it is common to oxidize ammoniacal nitrogen to nitrate nitrogen, although the required oxygen supply is increased.

  If there is a measurement device that can independently monitor nitrite nitrogen in water, the biological nitrification denitrification method as described above can detect the stage in which ammonia nitrogen is oxidized to nitrite nitrogen, thus saving energy from the current level. Driving is possible.

In recent years, a nitrogen removal method using anaerobic ammonia oxidizing bacteria (anammox bacteria) has been proposed as a new biological nitrogen removal method (for example, Non-Patent Document 2). The reaction of the anaerobic ammonium oxidation, NO ₂ ^- is reduced to NH ₂ OH, N ₂ H ₄ is produced from NH ₂ OH and which is reduced NH ₄ ⁺ and is denitrified to finally N ₂ gas . In terms of stoichiometry, it is represented by the following formula.
NH 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 (1)
In the nitrogen removal method using anammox bacteria, (1) the anammox bacterium carries out an autotrophic denitrification reaction, which eliminates the need for an organic carbon source as a hydrogen donor. (2) half the amount of NH ₄ ^{+ in} the treated water NO ₂ ^- it is sufficient oxidation can be reduced oxygen supply to, (3) the excess sludge amount can be reduced, and can be processed in (4) high nitrogen processing speed as compared with the conventional biological nitrogen treatment It has the following features. The application of this anaerobic ammonia oxidation process is said to be suitable for wastewater with a low organic matter concentration (low C / N ratio) and a relatively high ammoniacal nitrogen (NH ₄ ⁺ -N) concentration.

Japanese Patent Laid-Open No. 06-123705 JP 2010-197383 A

Water Environment Handbook, Japan Water Environment Society, Asakura Shoten, October 2006, p. 241 Fresh water technology handbook. 2004, Water Production Promotion Center, edited by the Water Production Technology Handbook Editorial Planning Committee, November 2004, p. 75

  However, among ammoniacal nitrogen and nitrite nitrogen that are substrates in the reaction by anammox bacteria, if the concentration of nitrite nitrogen is high, anaerobic ammonia oxidation reaction may be inhibited. Therefore, in order to perform anaerobic ammonia oxidation treatment while maintaining the activity of anammox bacteria at a high level, it is important to monitor the concentration of nitrite nitrogen that is a substrate and may be an inhibitor depending on the concentration It becomes.

  Therefore, an object of the present invention is to provide a nitrite nitrogen concentration monitoring device and a nitrite nitrogen concentration monitoring method capable of monitoring the nitrite nitrogen concentration of water to be treated in a water treatment process.

  The nitrite nitrogen concentration monitoring method of the present invention that achieves the above object comprises treating treated water containing ammoniacal nitrogen and nitrite nitrogen in the presence of anaerobic ammonia oxidizing bacteria, and treating the treated water. A nitrite nitrogen concentration monitoring method for monitoring the nitrite nitrogen concentration of treated water that has been lowered in a treatment tank that removes nitrite nitrogen from the treatment tank, wherein the treated water flowing into the treatment tank is sublimated. Irradiate the light absorbed by nitrate nitrogen, measure the absorbance to this light, irradiate the water to be treated treated in the treatment tank with the light absorbed by nitrite nitrogen, and absorb the light to this light Measured based on the difference between the absorbance measured in the treated water flowing into the treatment tank and the absorbance measured in the treated water treated in the treatment tank, and decreased by being treated in the treatment tank Calculate nitrite nitrogen concentration of treated water It is characterized in Rukoto.

  Further, the nitrite nitrogen concentration monitoring method of the present invention that achieves the above object is characterized in that the treated water containing ammonia nitrogen and nitrite nitrogen is treated in the presence of anaerobic ammonia bacteria, A nitrite nitrogen concentration monitoring method for monitoring the concentration of nitrite nitrogen in water to be treated flowing into a treatment tank for removing nitrite nitrogen in water, wherein the water to be treated flowing into the treatment tank is nitrite-based Irradiate light absorbed by nitrogen, measure the absorbance to this light, irradiate the treated water treated in the treatment tank with light absorbed by nitrite nitrogen, and measure the absorbance to this light Then, based on the difference between the absorbance measured in the treated water flowing into the treatment tank and the absorbance measured in the treated water treated in the treatment tank, the amount of the treated water flowing into the treatment tank is reduced. It is characterized by calculating nitrate nitrogen concentration There.

  Further, the nitrite nitrogen concentration monitoring method of the present invention that achieves the above object is characterized in that the treated water is treated in the presence of microorganisms and treated in a treatment tank that performs biological nitrification / denitrification of the treated water. A nitrite nitrogen concentration monitoring method for monitoring the concentration of nitrite nitrogen in the treated water, wherein the water to be treated flowing into the treatment tank is irradiated with light absorbed by nitrite nitrogen, The light absorption is measured, and the water to be treated flowing into the treatment tank is irradiated with light that is not absorbed by nitrite nitrogen and is absorbed by organic substances contained in the treatment water. Is measured by irradiating light to be treated by the nitrite nitrogen to the treated water treated in the treatment tank, and measuring the light absorption to the treated water treated in the treatment tank. , Light that is not absorbed by nitrite nitrogen, Irradiate the light absorbed by the organic matter contained in the water to be treated, measure the absorbance to this light, and previously absorb the light absorbed by the nitrite nitrogen and the light absorbed by the organic matter. The correlation with the absorbance is calculated, and the absorbance with respect to the light absorbed by the nitrite nitrogen measured in the treated water flowing into the treatment tank is determined by the organic matter measured in the treated water flowing into the treatment tank. Correction based on the absorbance to the absorbed light, the absorbance to the light absorbed by nitrite nitrogen measured in the treated water after being treated in the treatment tank, after being treated in the treatment tank Correction based on the absorbance to light absorbed by the organic matter measured in the treated water, corrected absorbance measured in the treated water flowing into the treatment tank, and the corrected treatment In based on the difference between the measured absorbance in the treated water to be treated is characterized by calculating the nitrite nitrogen concentration in the treated solution which has been processed in the processing bath.

  Moreover, the nitrite nitrogen concentration monitoring method of the present invention that achieves the above object is characterized in that, in the nitrite nitrogen concentration monitoring method, the wavelength of light absorbed by the nitrite nitrogen is 330 to 380 nm. It is a feature.

  Moreover, the nitrite nitrogen concentration monitoring device of the present invention that achieves the above object is characterized by treating the water to be treated containing ammoniacal nitrogen and nitrite nitrogen in the presence of anaerobic ammonia oxidizing bacteria, A nitrite-nitrogen concentration monitoring device that monitors the nitrite-nitrogen concentration of treated water that has been treated and reduced in a treatment tank that removes nitrite-nitrogen in the treated water, and that is to be treated flowing into the treatment tank First light measurement means for irradiating light absorbed by nitrite nitrogen to the water and measuring the absorbance to this light; and water to be treated after being treated in the treatment tank absorbed by nitrite nitrogen Based on the difference between the absorbance measured by the second absorbance measuring means, the second absorbance measuring means for measuring the absorbance to the light, the absorbance measured by the first absorbance measuring means, and the absorbance measured by the second absorbance measuring means Treated in the treatment tank It is characterized by comprising a calculating means for calculating the nitrite nitrogen concentration in the water to be treated was reduced Te.

  Moreover, the nitrite nitrogen concentration monitoring device of the present invention that achieves the above object is characterized by treating the water to be treated containing ammoniacal nitrogen and nitrite nitrogen in the presence of anaerobic ammonia oxidizing bacteria, A nitrite nitrogen concentration monitoring device for monitoring the concentration of nitrite nitrogen in water to be treated flowing into a treatment tank for removing nitrite nitrogen in the water to be treated, wherein A first absorbance measuring means for irradiating light absorbed by nitrate nitrogen and measuring the absorbance of the light, and light absorbed by nitrite nitrogen in the water to be treated after being treated in the treatment tank Based on the difference between the absorbance measured by the second absorbance measuring means, the second absorbance measuring means that measures the absorbance to the light by irradiation, the absorbance measured by the first absorbance measuring means, and the absorbance measured by the second absorbance measuring means, Water to be treated flowing into the treatment tank Calculating means for calculating the nitrite nitrogen concentration is characterized by having a.

  In addition, the nitrite nitrogen concentration monitoring device of the present invention that achieves the above object is a treatment tank that treats treated water in the presence of microorganisms and performs biological nitrification / denitrification of the treated water. A nitrite nitrogen concentration monitoring device for monitoring the nitrite nitrogen concentration of the treated water, wherein the water to be treated flowing into the treatment tank is irradiated with light absorbed by the nitrite nitrogen. First absorbance measuring means for measuring the absorbance to light, and second absorbance measuring means for irradiating the water to be treated treated in the treatment tank with light absorbed by nitrite nitrogen and measuring the absorbance to this light And a third absorbance measuring means for irradiating the water to be treated flowing into the treatment tank with light that is not absorbed by nitrite nitrogen and that is absorbed by organic matter, and measuring the absorbance of the light, To treated water treated in the treatment tank Light that is not absorbed by nitrite nitrogen and is irradiated with light that is absorbed by an organic substance, and the absorbance measured by the first absorbance measuring means is measured by measuring the absorbance of the light. Correction is made based on the absorbance measured by the third absorbance measuring means, the absorbance measured by the second absorbance measuring means is corrected based on the absorbance measured by the fourth absorbance measuring means, and the corrected first Based on the difference between the absorbance measured by the first absorbance measuring means and the corrected absorbance measured by the second absorbance measuring means, the change in the concentration of nitrite nitrogen in the treated water treated in the treatment tank is determined. And a calculating means for calculating.

  According to the above invention, it can contribute to providing the nitrite nitrogen concentration monitoring method and the nitrite nitrogen concentration monitoring apparatus which can monitor the nitrite nitrogen concentration of the to-be-processed water of a water treatment process.

1 is a system configuration diagram of a nitrite nitrogen concentration monitoring apparatus according to Embodiment 1 of the present invention. It is a schematic block diagram of the light absorbency measurement means of the nitrite nitrogen concentration monitoring apparatus which concerns on Embodiment 1 of this invention. It is a measurement result of the absorption spectrum in sample water and various nitrogen-like standard solutions. It is a figure (calibration curve) which shows the relationship between the density | concentration of a nitrite nitrogen standard solution, and the light absorbency with respect to the light of wavelength 353nm of the nitrite nitrogen standard solution in the density | concentration. It is a figure which shows the daily change of the light absorbency with respect to the light of wavelength 353nm of the to-be-processed water which flows into the process tank of the anaerobic ammonia oxidation process process which concerns on an Example, or the process water which flows out of a process tank. The processing tank calculated based on the calculated value of the nitrite nitrogen concentration reduced by the processing tank calculated by the processing tank calculated by the nitrite nitrogen concentration monitoring apparatus according to Embodiment 1 of the present invention and the actual measurement value by the official method It is a figure which shows the relationship with the calculated value of the nitrite nitrogen density | concentration which was processed and decreased. It is a system block diagram of the nitrite nitrogen concentration monitoring apparatus which concerns on Embodiment 2 of this invention. It is a system block diagram of the nitrite nitrogen concentration monitoring apparatus which concerns on Embodiment 3 of this invention. It is a schematic block diagram of the UV measurement means of the nitrite nitrogen concentration monitoring apparatus which concerns on Embodiment 3 of this invention. It is a system block diagram of the nitrite nitrogen concentration monitoring apparatus which concerns on Embodiment 4 of this invention. It is a schematic block diagram of the light absorbency measurement means of the nitrite nitrogen concentration monitoring apparatus which concerns on Embodiment 4 of this invention.

  With reference to the drawings, a nitrite nitrogen concentration monitoring method and a nitrite nitrogen concentration monitoring apparatus according to an embodiment of the present invention will be described by illustrating an anaerobic ammonia oxidation treatment process by anammox bacteria.

(Embodiment 1)
As shown in FIG. 1, a nitrite nitrogen concentration monitoring apparatus 1 according to Embodiment 1 of the present invention includes an absorbance measurement unit a2, an absorbance measurement unit b3, and a calculation unit 4, and includes an anaerobic ammonia oxidation treatment tank 5 ( Hereinafter, the nitrite nitrogen concentration change in the treatment tank 5) is monitored.

  The absorbance measurement means a2 is provided in the supply pipe 6 that supplies the water to be treated to the treatment tank 5 that performs the denitrification reaction by anammox bacteria. The water to be treated is sampled from the supply pipe 6 by the pump 7 to the absorbance measuring means a2. Then, the water to be treated is irradiated with light having a wavelength of 353 nm, and the absorbance a with respect to this light is measured.

  The absorbance measurement means b3 is provided in the discharge pipe 8 that discharges the water to be treated (hereinafter, treated water) after being treated in the treatment tank 5. In the absorbance measurement means b3, the treated water is sampled from the discharge pipe 8 by the pump 9. Then, the treated water is irradiated with light having a wavelength of 353 nm, and the absorbance b with respect to this light is measured.

  The calculation means 4 receives the absorbance a from the absorbance measurement means a2 and the absorbance b from the absorbance measurement means b3, respectively. Calculate the concentration of nitrite nitrogen in the treated water supplied. In the treatment tank 5, the concentration of nitrite nitrogen in the water to be treated is reduced by the reaction (anammox reaction) by the anammox bacteria represented by the formula (1). That is, since the concentration of nitrite nitrogen in the treated water is higher than the concentration of nitrite nitrogen in the treated water, the absorbance a is higher than the absorbance b. Therefore, the absorbance b is subtracted from the absorbance a, and the decrease in the concentration of nitrite nitrogen in the water to be treated treated in the treatment tank 5 is calculated.

  In the anaerobic ammonia oxidation process, treated water containing ammonia nitrogen and nitrite nitrogen is transferred to the treatment tank 5 from the supply pipe 6. The anammox reaction shown in the formula (1) occurs by the anammox bacteria held in the treatment tank 5, and ammonia nitrogen and nitrite nitrogen in the treated water react to generate nitrogen, thereby denitrifying the treated water. Is done. The treated water treated in the treatment tank 5 is discharged through the discharge pipe 8.

  As shown in FIG. 2, a part of the water to be treated flowing through the supply pipe 6 is introduced into the cell 10 of the absorbance measuring means a2 by the pump 7. Then, the light from the light source 11 passes through the lens 12 and the interference filter 13 so that the cell 10 is irradiated with light having a wavelength of 353 nm. Then, the intensity of light transmitted through the cell 10 is detected by the photodiode 14, and the absorbance a is calculated by the calculation unit 15 based on the detected light intensity. The calculated absorbance a is input to the calculation means 4 shown in FIG. The configuration of the absorbance measurement unit b3 is the same as that of the absorbance measurement unit a2 shown in FIG. 2, the absorbance b of the treated water flowing through the discharge pipe 8 is calculated, and the calculated absorbance b is input to the calculation unit 4. .

  The computing means 4 subtracts the absorbance b from the absorbance a, and computes the difference in nitrite nitrogen concentration between the treated water and the treated water, which is reduced by the anaerobic ammonia oxidation treatment. Moreover, the nitrite nitrogen concentration of the to-be-processed water which flows into the processing tank 5 is estimated based on the nitrite nitrogen concentration difference calculated | required by this calculation.

(Example)
By giving a specific example, the nitrite nitrogen concentration monitoring apparatus 1 and the nitrite nitrogen concentration monitoring method using this apparatus according to Embodiment 1 of the present invention will be described in more detail. In the examples, a treatment test was performed in which the effluent of the extracted sludge from the sewage treatment plant was treated and the ammonia nitrogen in the solution was separated and removed as nitrogen gas.

  The liquid to be treated was treated in a partial nitritation treatment tank (PN tank) that aerated in the presence of aerobic ammonia-oxidizing bacteria (nitrifying bacteria) to convert part of the ammoniacal nitrogen to nitrite nitrogen. Thereafter, the water to be treated after being treated in the PN tank was treated in an anaerobic ammonia oxidation treatment tank (AX tank) in which ammonia nitrogen and nitrite nitrogen were reacted in the presence of anammox bacteria to convert to nitrogen. In this treatment test, the nitrite nitrogen concentration monitoring apparatus 1 shown in FIG. 1 was used to monitor the nitrite nitrogen concentration in the AX tank (that is, the treatment tank 5).

First, the absorption spectrum of the water to be treated (sample water) flowing into the AX tank was measured. In addition to the organic component, the water to be treated contains ammonia nitrogen, nitrite nitrogen, and nitrate nitrogen as nitrogen components. Absorption spectrum measurement includes treated water (filtered with 5C filter paper), ammonia standard solution (NH ₄ ⁺ -N 100 mg / L), nitrous acid standard solution (NO ₂ ^-- N 100 mg / L), nitric acid standard Each was performed with a solution (NO ₃ ⁻ —N 100 mg / L) solution. The measurement results are shown in FIG.

  As shown in FIG. 3, in the absorption region of 330 to 380 nm, it was confirmed that there was no absorption of nitrate nitrogen and ammonia nitrogen, and only nitrite nitrogen was absorbed. That is, it is understood that nitrite nitrogen can be detected without being affected by ammonia nitrogen and nitrate nitrogen by measuring the absorbance with respect to light having a wavelength of 330 to 380 nm.

  Further, as shown in FIG. 4, the relationship between the concentration of the nitrite nitrogen solution and the absorbance at the concentration with respect to light in the vicinity of a wavelength of 353 nm (light having a wavelength of 330 to 380 nm) is linear. Therefore, the absorbance of the solution containing nitrite nitrogen is measured, and the nitrite nitrogen concentration is calculated based on this linear relationship (calibration curve). The detection range of the nitrite nitrogen concentration is not particularly limited, but from the calibration curve shown in FIG. 4, the measurement of the nitrite nitrogen concentration in the range of at least 0 to 1000 mg-N / L is possible. It turns out that it is possible.

  FIG. 5 shows the absorbance a (that is, the measured value in the absorbance measurement means a2) of the water to be treated flowing into the AX tank at the wavelength 353 nm in the nitrite nitrogen concentration monitoring apparatus 1, and the AX tank after the treatment in the AX tank. It is a measurement result of the light absorbency b (namely, measured value in the light absorbency measuring means b3) with respect to the light of wavelength 353nm of treated water.

  As shown in FIG. 5, the absorbance a of the water to be treated varies greatly with the elapsed days. This is because not only the concentration of nitrite nitrogen in the treated water flowing into the AX tank changes, but also the concentration of substance substances other than nitrite nitrogen (hereinafter referred to as inhibitors) that absorb light with a wavelength of 353 nm. It is thought to change. As an inhibitor, an organic substance or the like can be considered. Further, the absorbance b of the treated water also greatly changes with the elapsed days. This is thought to be because the concentration of nitrite nitrogen in the treated water (nitrite nitrogen not consumed in the anammox reaction) and the concentration of the inhibitor flowing into the AX tank change.

  It is considered that the difference between the absorbance a of the treated water and the absorbance b of the treated water is based on a decrease in nitrite nitrogen concentration due to consumption by the anammox reaction. Therefore, the difference between the absorbance a and the absorbance b was calculated, and the nitrite nitrogen concentration decreased by the anammox reaction was calculated. In addition, the ion chromatographic method, which is an official method for measuring nitrite nitrogen concentration, measures the nitrite nitrogen concentration of treated water and the nitrite nitrogen concentration of treated water, and decreases due to the anammox reaction in the AX tank. The nitrite nitrogen concentration was calculated.

  FIG. 6 shows the relationship between the calculated value calculated from the actual measurement value by the official method of the nitrite nitrogen concentration decreased by the anammox reaction and the calculated value calculated from the absorbance.

  As shown in FIG. 6, it can be seen that the nitrite nitrogen concentration calculated from the absorbance is in good agreement with the nitrite nitrogen concentration calculated based on the actual measurement value. That is, from the result shown in FIG. 5, it can be confirmed that there is an absorption component of light having a wavelength of 353 nm due to the inhibitory substance in the treated water and the treated water, but from the result shown in FIG. It shows that there was almost no increase or decrease in absorption components other than nitrite nitrogen (it was negligibly small).

That is, when the absorbance of light having a wavelength of 353nm absorbance E _353, each absorbance E ₃₅₃ of the water to be treated and treated water, (2), represented by equation (3).
Absorbance E _{353 of} treated water
= (NO of the water to be treated ₂ ^- absorbance E ₃₅₃ of -N) + (absorbance E ₃₅₃ inhibitors of the water to be treated)
... (2)
Absorbance E _{353 of} treated water
= (NO of treated water ₂ ^- absorbance E ₃₅₃ of -N) + (absorbance E ₃₅₃ inhibitors of the treated water)
... (3)
And in the AX tank, when there is almost no increase or decrease in the absorption component of the inhibitor,
(Absorbance E ₃₅₃ inhibitors of the water to be treated) = (Absorbance E ₃₅₃ inhibitors of the treated water)
... (4)
Therefore, from the equations (2) to (4), the absorbance E _{353 of the} treated water—the absorbance E _{353 of the} treated water
= (NO of treated water ₂ ^- absorbance E ₃₅₃ of -N) - (NO in the water to be treated ₂ ^- absorbance E ₃₅₃ of -N)
... (5)
Thus, the difference between the absorbance a of the water to be treated and the absorbance b of the treated water is the difference in absorbance due to the nitrite nitrogen removed in the AX tank.

  As described above, according to the nitrite nitrogen concentration monitoring apparatus 1 according to the first embodiment, the nitrite nitrogen concentration decreased due to the reaction in the AX tank (processing tank 5) can be quickly detected. Based on this detection result, it can be checked whether the reaction in the AX tank is proceeding without delay. For example, when processing in the AX tank is performed with the same nitrogen load, by detecting that the concentration of the removed nitrite nitrogen has decreased (in other words, between treated water and treated water By detecting that the nitrous acid nitrogen concentration difference has become smaller), it can be determined that the processing state in the AX tank has deteriorated. In addition, when it is almost impossible to detect a decrease in nitrite nitrogen concentration, it is assumed that the nitrogen removal reaction in the AX tank is not progressing. Can be controlled.

  Table 1 shows the nitrogen components (such as ammonia nitrogen) and pollutant components in the treated water flowing into the PN tank, the treated water flowing into the AX tank, and the treated water discharged from the AX tank in the treatment test of the example. The measured value by the official method of the average density | concentration of (Biochemical Oxygen Demand: BOD) is shown. In addition, ATU-BOD is BOD which suppressed nitrification reaction, and is the amount of pollution based on the organic substance which does not contain oxygen consumption in nitrification reaction.

  As shown in Table 1, the nitrite nitrogen concentration of the water to be treated increases by processing in the PN tank, and the nitrite nitrogen concentration and ammonia nitrogen concentration (that is, the total nitrogen concentration by processing in the AX tank) ) Is decreasing. Moreover, when the change of ATU-BOD is seen, it exists in the decreasing tendency in each process in a PN tank and an AX tank.

  Moreover, the removal rate of nitrite nitrogen in to-be-processed water changes with the process conditions of an AX tank. In the examples, as shown in Table 1, nitrite nitrogen remaining in the treated water flowing out from the AX tank has a low concentration. That is, a high removal rate of about 95% nitrite nitrogen is obtained in the AX tank, which indicates that the AX tank is operated under good processing conditions. However, if the treatment state deteriorates due to fluctuations in the inflow load or a decrease in anaerobic ammonia-oxidizing bacteria activity, the concentration of nitrite nitrogen in the treated water flowing out from the AX tank will increase. Therefore, by measuring the difference in the concentration of nitrite nitrogen before and after the AX tank, the processing state of the AX tank can be monitored. It is possible to perform control to stabilize the processing by changing the supply speed of the above.

  As described above, according to the nitrite nitrogen concentration monitoring apparatus 1 and the nitrite nitrogen concentration monitoring method according to Embodiment 1 of the present invention, the change in the nitrite nitrogen concentration in the anaerobic ammonia oxidation treatment tank (AX tank) can be quickly performed. Can be detected. And the process condition of an anaerobic ammonia oxidation processing tank can be grasped | ascertained by continuously monitoring the nitrite nitrogen concentration removed by the anaerobic ammonia oxidation process. As a result, in the anaerobic ammonia oxidation process, when the treatment status tends to deteriorate, measures such as reducing the nitrogen load by controlling the concentration of treated water and the amount of treated water supplied can be taken. .

  In addition to nitrite nitrogen, the water to be treated that flows into the AX tank contains components that absorb light with a wavelength of 353 nm (for example, coloring components), so simply measure the absorbance and measure the absorbance. The nitrite nitrogen concentration may not be calculated using the value and the calibration curve.

  In the embodiment of the present invention, the object to be removed from the AX tank is nitrite nitrogen, and the concentration of nitrite nitrogen in the treated water and the treated water varies greatly. On the other hand, since the coexisting inhibitor is not an object to be removed in the AX tank, it is considered that it is not removed or a small amount even if it is removed. Therefore, the nitrite nitrogen removed in the AX tank can be estimated by calculating the difference in absorbance measured between the treated water flowing into the AX tank and the treated water flowing out from the AX tank.

  As shown in Table 1, when most nitrite nitrogen is removed by the anammox reaction in the AX tank, the concentration of nitrite nitrogen removed in the AX tank is the water to be treated flowing into the AX tank. This is considered to be almost equal to the nitrite nitrogen concentration. Therefore, the processing conditions of the AX tank can be controlled based on the nitrite nitrogen concentration of the water to be treated flowing into the AX tank.

(Embodiment 2)
A nitrite nitrogen concentration monitoring method and a nitrite nitrogen concentration monitoring apparatus according to Embodiment 2 of the present invention will be described in detail with reference to FIG. The nitrite nitrogen concentration monitoring device 16 according to the second embodiment of the present invention includes one absorbance measurement unit 17, and the absorbance measurement unit 17 measures the absorbance a of the treated water and the absorbance b of the treated water. It is. Therefore, the same code | symbol is attached | subjected about the thing similar to the nitrite nitrogen concentration monitoring apparatus 1 which concerns on Embodiment 1, and detailed description is abbreviate | omitted.

  As shown in FIG. 7, the nitrite nitrogen concentration monitoring device 16 according to Embodiment 2 of the present invention includes an absorbance measurement unit 17 and a calculation unit 4, and is a sublimation in an anaerobic ammonia oxidation treatment tank (treatment tank 5). Monitor changes in nitrate nitrogen concentration.

  The absorbance measuring means 17 includes a flow path switching valve 18 in a supply pipe 6 for supplying water to be treated to the treatment tank 5 for performing denitrification reaction by anammox bacteria and a discharge pipe 8 for discharging the treated water treated in the treatment tank 5. Provided. The absorbance measuring means 17 samples the treated water in the supply pipe 6 or the treated water in the discharge pipe 8. And the light with a wavelength of 353 nm is irradiated to this to-be-treated water or treated water, and the light absorbency with respect to this light is measured.

  The calculation means 4 receives the absorbance a and absorbance b from the absorbance measurement means 17 and reduces the concentration of nitrite nitrogen that has been processed and reduced in the treatment tank 5 and the nitrite nitrogen of the water to be treated supplied to the treatment tank 5. Calculate the concentration.

  In the anaerobic ammonia oxidation process, treated water containing ammonia nitrogen and nitrite nitrogen is transferred to the treatment tank 5 from the supply pipe 6. The anammox reaction shown in the formula (1) occurs by the anammox bacteria held in the treatment tank 5, and ammonia nitrogen and nitrite nitrogen in the treated water react to generate nitrogen, thereby denitrifying the treated water. Is done. The treated water treated in the treatment tank 5 is discharged through the discharge pipe 8.

  In the absorbance measuring means 17, the water to be treated is sampled from the supply pipe 6 by switching the flow path switching valve 18. Then, the absorbance a of the sampled water to be treated is measured. Further, after a predetermined time has elapsed, the flow path switching valve 18 is switched and the treated water is sampled from the discharge pipe 8. Then, the absorbance b of the sampled treated water is measured. The order of the absorbance measurement of the water to be treated and the treated water in the absorbance measuring means 17 is not particularly limited, but the reaction in the treatment tank 5 is a reaction in which nitrite nitrogen is reduced. After measuring the absorbance b of the sample, the measurement error of the absorbance can be reduced by switching the flow path switching valve 18 and measuring the absorbance of the water to be treated a.

  The computing means 4 subtracts the absorbance b from the absorbance a, and computes the nitrite nitrogen concentration difference between the treated water and treated water of the anaerobic ammonia oxidation treatment from the difference. Moreover, the nitrite nitrogen concentration of the to-be-processed water which flows into the processing tank 5 is estimated based on the calculated nitrite nitrogen concentration.

  As described above, the nitrite nitrogen concentration monitoring device 16 according to the second embodiment of the present invention has one absorbance measuring unit 17, and thus has a configuration compared to the nitrite nitrogen concentration monitoring device 1 according to the first embodiment. Simplified.

  And also in the nitrite nitrogen concentration monitoring apparatus 16 which concerns on Embodiment 2 of this invention, similarly to the nitrite nitrogen concentration monitoring apparatus 1 which concerns on Embodiment 1, nitrite nitrogen of an AX tank (treatment tank 5) The concentration could be monitored.

(Embodiment 3)
As shown in FIG. 8, the nitrite nitrogen concentration monitoring device 19 according to the third embodiment of the present invention includes an absorbance measurement unit a2, an absorbance measurement unit b3, a UV measurement unit a20, a UV measurement unit b21, and a calculation unit 4. The nitrite nitrogen concentration change in the partial nitritation treatment tank (hereinafter referred to as treatment tank 22) is monitored. The absorbance measurement unit a2 and the absorbance measurement unit b3 are the same as the absorbance measurement unit of the first embodiment, and thus the same reference numerals are given and detailed description thereof is omitted.

  The UV measurement means a20 is provided in a supply pipe 23 that supplies water to be treated to a treatment tank 22 that performs a partial nitritation reaction by nitrifying bacteria. The water to be treated is sampled from the supply pipe 23 by the pump 24 to the UV measuring means a20. Then, the water to be treated is irradiated with UV light having a wavelength of 254 nm, and the absorbance UVa with respect to the UV light is measured. Further, the water to be treated is irradiated with VIS light (visible light) having a wavelength of 546 nm, and the absorbance (VISa) with respect to the VIS light is measured. In the UV measurement means a20, since UVa (or UVa-VISa) and the organic component have a correlation, the organic contamination concentration such as COD is measured, and since VISa and the turbid component have a correlation, turbidity. Or measure SS. Then, the measurement result of the UV measurement unit a20 is transmitted to the calculation unit 4. Further, the water to be treated after being measured by the UV measuring means a20 is transferred to the absorbance measuring means a2.

  The absorbance measuring unit a2 is provided at the subsequent stage of the UV measuring unit a20, and the water to be treated transferred from the UV measuring unit a20 is irradiated with light having a wavelength of 353 nm to measure the absorbance of the sampled treated water.

  The UV measurement means b21 is provided in the discharge pipe 25 that discharges the treated water treated in the treatment tank 22. The treated water is sampled from the discharge pipe 25 by the pump 26 to the UV measuring means b21. Then, in the UV measuring means b21, as in the UV measuring means a20, UVb (or UVb-VISb) and the organic component have a correlation, so that the organic pollution concentration such as COD is measured, and VISb and the turbid component Is correlated, and turbidity or SS is measured. Then, the measurement result of the UV measurement unit b21 is transmitted to the calculation unit 4. Moreover, the treated water after being measured by the UV measuring means b21 is transferred to the absorbance measuring means b3.

  The absorbance measuring unit b3 is provided at the subsequent stage of the UV measuring unit b21, and the treated water transferred from the UV measuring unit b21 is irradiated with light having a wavelength of 353 nm, and the absorbance of the sampled treated water is measured.

  The calculation means 4 receives the absorbance a from the absorbance measurement means a2 and the absorbance b from the absorbance measurement means b3, and calculates the concentration of nitrite nitrogen generated by processing in the treatment tank 22. The calculation means 4 receives UVa from UV measurement means a20 and UVb from UV measurement means b21, respectively, and corrects absorbance a and absorbance b.

In the treatment tank 22, the concentration of nitrite nitrogen increases due to a reaction (ammonia oxidation reaction) by nitrifying bacteria or the like shown in Formula (6).
2NH ₃ + 3O ₂ → 2HNO ₂ + 2H ₂ O (6)
That is, since the nitrite nitrogen concentration of the treated water is higher than the nitrite nitrogen concentration of the treated water, the absorbance b is higher than the absorbance a. Therefore, the nitrite nitrogen concentration of the treated water treated in the treatment tank 22 is calculated by subtracting the absorbance a from the absorbance b.

  Further, the nitrifying bacteria held in the treatment tank 22 are autotrophic bacteria, but heterotrophic BOD-oxidizing bacteria also coexist with each other, so that organic components are reduced. That is, unlike the anaerobic ammonia oxidation process of Embodiments 1 and 2, the absorbance of light having a wavelength of 330 to 380 nm due to the inhibitor may not be considered constant. Therefore, the UV measurement means a20 and the UV measurement means b21 measure the absorbance based on the organic component without being affected by the presence of the nitrite nitrogen component, and based on the measurement result, the absorbance measurement means a2 and the absorbance measurement means. The absorbance measured in b3 is corrected.

  In the partial nitritation process of ammonia nitrogen, water to be treated containing ammonia nitrogen is transferred to the treatment tank 22 from the supply pipe 23. The reaction shown in the formula (6) occurs by the bacterial group containing nitrifying bacteria and the like held in the treatment tank 22, and a part of the ammonia nitrogen in the for-treatment water is converted to nitrite nitrogen. The treated water treated in the treatment tank 22 is transferred to a subsequent anaerobic ammonia treatment tank (not shown) through the discharge pipe 25.

  Here, the UV measuring unit a20 (and the UV measuring unit b21) will be described by exemplifying an immersion type UV meter. The UV measuring unit a20 (and the UV measuring unit b21) includes a sampling type (flow cell type) type and an immersion type, and either type is applied to the nitrite nitrogen concentration monitoring device 19 according to the present embodiment. be able to.

  As shown in FIG. 9, in the immersion type UV meter, the light from the light source 11 is distributed to the reference side 28 and the measurement side 29 by the half mirror 27. The light extracted on the reference side 28 passes through an optical filter (not shown), the intensity is detected by the UV detector 30 and the VIS detector 31, and the detected reference signals (UV-R, VIS-R) are detected. Is transmitted to the calculation unit 33. The light on the measurement side 29 passes through parallel windows 34 and 34 through which sampled sample water flows, and then is divided into two lights (UV and VIS) by a half mirror 35, and an optical filter (not shown) is applied. The intensity is detected by the UV detector 36 and the VIS detector 37, and the detected measurement signals (UV-S, VIS-S) are transmitted to the calculation unit 33. The computing unit 33 calculates the COD concentration, the SS concentration, and the like based on the reference signal and the measurement signal.

  In the calculation means 4, the absorbance a corrected based on the measurement result of the UV measurement means a20 is subtracted from the absorbance b corrected based on the measurement result of the UV measurement means b21, and the partial nitritation step is performed from the difference. The generated nitrite nitrogen concentration (that is, the nitrite nitrogen concentration of the treated water) is calculated.

(Example)
The specific example is given and the nitrite nitrogen concentration monitoring apparatus 19 and the nitrite nitrogen concentration monitoring method according to Embodiment 3 of the present invention are described in more detail.

  In the example, similarly to the example of the first embodiment, a treatment test for separating and removing ammonia nitrogen in the liquid to be treated as the water to be treated using the sewage sludge desorption liquid from the sewage treatment plant was performed. .

  The liquid to be treated was treated in a partial nitritation treatment tank (PN tank) that aerated in the presence of nitrifying bacteria to convert a part of ammonia nitrogen to nitrite nitrogen. Then, the water to be treated after being treated in the PN tank is an anaerobic ammonia oxidation treatment tank that converts ammonia nitrogen and nitrite nitrogen to nitrogen in the presence of anaerobic ammonia oxidation bacteria (anammox bacteria) ( AX tank). In this treatment test, nitrite nitrogen in the treated water generated in the PN tank (treatment tank 22) was monitored by the nitrite nitrogen concentration monitoring device 19 shown in FIG.

In nitrite nitrogen concentration monitoring device 19, the correlation between the absorbance E ₃₅₃ to light the absorbance E ₂₅₄ and the wavelength 353nm for UV light in advance calculated (calibration curve), the absorbance E ₃₅₃ based on the absorbance E ₂₅₄ Make corrections.

That is, the absorbance of the water to be treated supplied to the PN tank and the absorbance of the treated water discharged from the PN tank are considered to be the same as the expressions (2) and (3) shown in the example of the first embodiment. It is done. However, in the PN tank, the expression (4) shown in the example of the first embodiment may not be satisfied.
Therefore, (2), (3) In the equation, based on the absorbance E ₃₅₃ of the organic pollutants that are correlated with the absorbance E ₂₅₄ organic pollutants, absorbance E ₃₅₃ and treated water of the for-treatment water absorbance E ₃₅₃ Correct the measured value. As shown in FIG. 3, sample water has absorption with respect to the light of wavelength 254nm and wavelength 353nm. The organic pollution absorbance E ₃₅₃ with respect to light having a wavelength of 353nm absorbance E ₂₅₄ and organic pollutants with respect to light having a wavelength of 254nm of material is in correspondence, the absorbance of the organic pollutants from the absorbance value E ₂₅₄ of the organic pollutants E ₃₅₃ Can be uniquely determined. That is, in the water to be treated (or treated water), the relationship between the absorbance E ₃₅₃ absorbance E ₂₅₄ and organic pollutants organic pollutants, the calibration curve, the organic pollutants from the absorbance E ₂₅₄ organic pollutants Absorbance E ₃₅₃ can be determined. In addition, because the form of organic matter is similar in the treated water of domestic wastewater and general river water, the ratio between the absorbance E ₂₅₄ (UV or UV-VIS) of the UV meter and the COD value that is an indicator of the concentration of organic matter is Because it is similar regardless of region, it can be applied to normal sample water.

Therefore, the equations (2) and (3) can be approximated as follows.
Absorbance E _{353 of} treated water
= (Absorbance E ₃₅₃ of NO ₂ ⁻ −N of water to be treated)
+ (Absorbance E ₃₅₃ of organic pollutant in water to be treated converted from absorbance E ₂₅₄ ) (7)
Absorbance E _{353 of} treated water
= (Absorbance E _{353 of} treated water NO ₂ ^-- N)
+ (Absorbance E ₃₅₃ of organic pollutant in treated water converted from absorbance E ₂₅₄ ) (8)
Based on the equations (7) and (8), the absorbance (NO) of nitrite nitrogen directly from the water to be treated or the treated water based on the measurement results of the absorbance E ₃₅₃ of the absorbance measuring means and the absorbance E ₂₅₄ of the UV measuring means. ₂ ⁻ −N absorbance E ₃₅₃ ) can be calculated. And the density | concentration of the nitrite nitrogen produced | generated by the PN tank can be calculated (or monitored) by taking the difference of the measurement result of (7), (8). In addition, as shown in Table 1, when the nitrite nitrogen concentration of the water to be treated flowing into the PN tank is low (or small enough to be ignored with respect to the generated amount), the calculated nitrite nitrogen concentration Is the nitrite nitrogen concentration of the discharged treated water.

  Thus, according to the nitrite nitrogen concentration monitoring device 19 according to the third embodiment, the change in nitrite nitrogen concentration of the water to be treated by the nitrite nitrogen generated by the reaction in the PN tank (treatment tank 22). It can be detected quickly. Based on the detection result, the processing state (processing state) in the PN tank can be monitored. Then, based on the detection result of the nitrite nitrogen concentration monitoring device 19, the PN tank can be controlled. Further, the concentration of nitrite nitrogen supplied to the AX tank at the subsequent stage can also be calculated.

  In the PN tank, the concentration of the organic component changes due to the aerobic treatment. That is, the concentration of the inhibitor that absorbs light used for measuring the absorbance of nitrite nitrogen may change. Therefore, by providing the UV measurement unit a20 and the UV measurement unit b21, the absorbance a is corrected based on UVa (absorbance b is corrected based on UVb), and the corrected absorbance measurement value and calibration curve are used. Thus, the concentration of nitrite nitrogen generated in the AX tank can be calculated.

  In the third embodiment, the nitrite nitrogen concentration monitoring method and the monitoring device in the PN tank have been described. However, even in normal biological nitrification / denitrification treatment, the nitrite nitrogen concentration and the organic matter concentration increase and decrease before and after the treatment. Therefore, Embodiment 3 is not limited to application to a PN tank, but can also be applied to a biological nitrification / denitrification tank.

  Further, the nitrite nitrogen concentration monitoring device 19 according to the third embodiment has a configuration in which the absorbance measurement unit a2 and the UV measurement unit a20 are separately provided, but the absorbance measurement unit a2 and the UV measurement unit a20 are incorporated. The absorbance a may be corrected based on UVa using a body. In this case, the integrated measurement means is provided with two flow paths, a flow path for measuring absorbance and a flow path for measuring UV (the same applies to the UV measurement means b21).

  In the embodiment, the absorbance is measured after the UV is measured, but the order of the UV measurement and the absorbance measurement is not particularly limited.

  In the description of the embodiment, the UV measurement unit a20 detects UVa and VISa, but this is in consideration of the influence of turbidity on the UVa measurement value. That is, when the influence of turbidity or the like cannot be ignored, UV light and VIS light are measured to correct for subtracting the absorbance based on turbidity, and ultraviolet absorbance UVa is measured. Therefore, when measuring the ultraviolet absorbance in the water to be treated with little influence of turbidity, the absorbance a of the absorbance measuring means a2 is corrected with the measurement value based on the measurement of only UV light without correcting the influence of turbidity. (The same applies to the UV measuring means b21).

(Embodiment 4)
A nitrite nitrogen concentration monitoring device 38 according to Embodiment 4 of the present invention will be described with reference to FIG. In addition, the nitrite nitrogen concentration monitoring apparatus 38 according to the fourth embodiment is the same as the nitrite nitrogen concentration monitoring apparatus 1 of the first embodiment, including one absorptiometric measurement means 39, and water to be treated flowing into the reaction tank 5. The absorbance a is measured by the absorbance measuring means 39 and the absorbance b of the treated water discharged from the reaction vessel. Therefore, the same code | symbol is attached | subjected about the structure similar to the nitrite nitrogen concentration monitoring apparatus 1 of Embodiment 1, and the detailed description is abbreviate | omitted.

  As shown in FIG. 10, the nitrite nitrogen concentration monitoring device 38 according to Embodiment 4 of the present invention includes an absorbance measurement unit 39 and a calculation unit 4, and is a sublimation in an anaerobic ammonia oxidation treatment tank (treatment tank 5). Monitor changes in nitrate nitrogen concentration.

  The absorbance measuring means 39 is connected to a supply pipe 6 that supplies water to be treated to the treatment tank 5 and a discharge pipe 8 that discharges the treatment water from the treatment tank 5. The absorbance measuring means 39 includes a flow path 39a through which a part of the water to be treated from the supply pipe 6 flows and a path 39b through which a part of the treated water from the discharge pipe 8 flows. And as shown in FIG. 11, the light from one light source 11 is used for the light absorbency measurement of the sample water which distribute | circulates the flow path 39a and the flow path 39b. The absorbance measuring means 39 measures the absorbance a and absorbance b of the sample water flowing through the respective paths 39a and 39b. Then, the absorbance a and absorbance b measured by the absorbance measuring means 39 are transmitted to the computing means 4. In FIG. 11, the same components as those of the absorbance measurement unit a2 shown in FIG. 2 are denoted by the same reference numerals, and detailed description thereof is omitted.

  The calculating means 4 calculates the nitrite nitrogen concentration of the water to be treated which has been treated and reduced in the treatment tank 5 by taking the difference between the absorbance a and the absorbance b. Moreover, the nitrite nitrogen concentration of the to-be-processed water which flows into the processing tank 5 is estimated.

  As described above, according to the nitrite nitrogen concentration monitoring apparatus 38 according to Embodiment 4 of the present invention, in addition to the effects of the nitrite nitrogen concentration monitoring apparatus 1 according to Embodiment 1 of the present invention, absorbance measurement is performed. The light source 11 used in the means 39 can be shared.

  Further, since the absorbance a and the absorbance b of the treated water can be measured in real time, there is no time lag due to measurement switching.

  In the nitrite nitrogen concentration monitoring apparatus 19 according to Embodiment 3 of the present invention, the absorbance measurement means a2, the absorbance measurement means b3, the UV measurement means a20, and the UV measurement means b21 are set as a single measurement means, In order to measure the absorbance (absorbance a, absorbance b, UVa, UVb), two channels through which treated water and treated water circulate may be provided to monitor the nitrite nitrogen concentration in real time. In this case, as described with reference to FIG. 9, a plurality of wavelengths can be measured from a single light source by using an optical mirror.

  As described above, according to the nitrite nitrogen concentration monitoring apparatus and the nitrite nitrogen concentration monitoring method of the present invention, the nitrite nitrogen concentration monitoring apparatus and the nitrite nitrogen concentration monitoring method are processed (generated or reduced) in the partial nitritation treatment tank or the anaerobic ammonia oxidation treatment tank. The nitrite nitrogen concentration can be quickly grasped. And it can grasp | ascertain quickly the nitrite nitrogen density | concentration of the to-be-processed water (or outflowed treated water) which flows in into a partial nitritation processing tank and anaerobic ammonia oxidation processing tank.

  In particular, in the anaerobic ammonia oxidation process, denitrification from ammonia nitrogen and nitrite nitrogen makes monitoring of ammonia nitrogen and nitrite nitrogen important in process monitoring control (for example, due to nitrite nitrogen) It is said that the inhibitory concentration of the anammox reaction is about 200 mg / N / L or more). Further, the nitrite nitrogen of water to be treated in this process has a high concentration (in the order of several hundreds to several thousand mg-N / L), and the nitrite nitrogen of the treated water as a result of the process has a low concentration ( Several mg-N / L). In addition, the anammox reaction has a high reaction rate and is often performed with the residence time of the treated water in the reaction tank being short, so when it is inhibited by nitrite nitrogen, nitrite nitrogen of the treated water quality The concentration of increases rapidly.

  Since the nitrite nitrogen concentration monitoring method and the nitrite nitrogen concentration monitoring device of the present invention can quickly measure the nitrite nitrogen concentration of the water to be treated in a wide concentration range (0 to 1000 mg-N / L or more), It can be applied to monitor nitrite nitrogen concentration in anaerobic ammonia oxidation process. And since the nitrite nitrogen concentration can be calculated quickly (monitoring the nitrite nitrogen concentration in real time), in the anaerobic ammonia oxidation treatment where the treatment is performed at a very high nitrogen treatment rate, the nitrite nitrogen It can be monitored whether the concentration does not inhibit the anammox reaction. That is, the processing status of the anammox reaction can be grasped.

  In this way, the nitrite nitrogen concentration in the anaerobic ammonia oxidation process can be measured quickly and accurately, making it easier to control the anaerobic ammonia oxidation process and anaerobic ammonia with a high nitrogen treatment capacity. It can contribute to promoting the introduction of oxidation treatment processes. And since the apparatus which measures a light absorbency does not require a precise structure and delicate apparatus adjustment, it can be used as ancillary facilities of water treatment apparatuses, such as an anaerobic ammonia oxidation process.

  The nitrite-nitrogen concentration monitoring method and the nitrite-nitrogen concentration monitoring device of the present invention are not limited to the above-described embodiment, and can be appropriately changed in design without impairing the effects of the invention. For example, the wavelength of light used for absorbance measurement by the absorbance measurement means is not limited to 353 nm, and the nitrite nitrogen concentration can be calculated if it is 330 to 380 nm. Further, the wavelength of light used for the UV measuring means is not limited to 254 nm and 546 nm, and the concentration of organic matter can be detected without being affected by the concentration of nitrite nitrogen, such as a wavelength in the vicinity of the wavelength (± 10 nm). Light having a wavelength may be appropriately selected and used.

  Similarly to the UV measuring means, the absorbance measuring means is not limited to the sampling type (flow cell method), and the immersion type is applicable to the nitrite nitrogen concentration monitoring apparatus and the nitrite nitrogen concentration monitoring method of the present invention. Can do.

  In addition, as treated water, it can be applied to monitoring nitrite nitrogen concentration in nitrogen removal process in various wastewater treatment such as sewage treatment, industrial wastewater (food, semiconductor, leather tanning) treatment, livestock wastewater treatment, etc. is there.

  In addition, by using the nitrite nitrogen concentration monitoring device of the present invention in a conventional partial nitritation process by denitrifying bacteria, the nitrite nitrogen concentration of water to be treated can be monitored and aeration power can be reduced. . Moreover, it can be used as a monitoring device for the concentration of nitrite nitrogen in a reaction tank by conventional denitrifying bacteria.

  If turbidity exists in the water to be treated and the turbidity component has a large effect on the measured value, the water to be treated should be treated with a filtration filter that can remove the turbidity before measuring the absorbance. By filtering the filter, it is possible to reduce the influence of contamination on the absorbance measurement value and improve the measurement accuracy of the nitrite nitrogen concentration. As the filter used for this filtration operation, known ones such as filter paper can be used, and as materials, ceramic, glass fiber, nitrocellulose, cellulose acetate, polyvinylidene fluoride (PVDF), ion exchange cellulose, nylon (registered trademark), Polytetrafluoroethylene (PTFE), polycarbonate and the like can be used. Moreover, you may utilize the sand filtration apparatus which is the pre-processing apparatus for the turbidity removal for the measuring instruments for water and sewage as another filtration operation.

1, 16, 19, 38 ... Nitrite nitrogen concentration monitoring device 2 ... Absorbance measuring means a (first absorbance measuring means)
3. Absorbance measuring means b (second absorbance measuring means)
4. Calculation means 5 ... Processing tank (anaerobic ammonia oxidation processing tank)
17, 39 ... Absorbance measuring means 18 ... Flow path switching valve 20 ... UV measuring means a (third absorbance measuring means)
21 ... UV measuring means b (fourth absorbance measuring means)
22 ... Treatment tank (partial nitritation tank)

Claims (3)

Nitrite nitrogen concentration for monitoring the nitrite nitrogen concentration of treated water treated in a treatment tank that treats the treated water in the presence of microorganisms and performs biological nitrification / denitrification of the treated water A monitoring method,
Irradiate the water to be treated flowing into the treatment tank with light absorbed by nitrite nitrogen, and measure the absorbance to this light.
The light to be treated that flows into the treatment tank is light that is not absorbed by nitrite nitrogen, and is irradiated with light that is absorbed by the organic matter contained in the water to be treated.
Irradiating the water to be treated treated in the treatment tank with light absorbed by nitrite nitrogen, and measuring the absorbance to this light,
The water to be treated treated in the treatment tank is light that is not absorbed by nitrite nitrogen, and is irradiated with light that is absorbed by the organic matter contained in the water to be treated, and measures the absorbance to this light,
Calculate the correlation between the absorbance of light absorbed by the nitrite nitrogen and the absorbance of light absorbed by the organic matter in advance,
The absorbance for light absorbed by nitrite nitrogen measured in the treated water flowing into the treatment tank is based on the absorbance for light absorbed by organic matter measured in the treated water flowing into the treatment tank. Correct,
Absorbance with respect to light absorbed by nitrite nitrogen measured in the water to be treated after being treated in the treatment tank is absorbed by the organic matter measured in the water to be treated after being treated in the treatment tank. Correct based on the absorbance to light,
Based on the difference between the absorbance measured in the treated water flowing into the treated tank and the corrected absorbance measured in the treated water treated in the treated tank, the treated water is treated in the treated tank. A method for monitoring a nitrite nitrogen concentration, comprising calculating a nitrite nitrogen concentration in a liquid to be treated. The nitrite nitrogen concentration monitoring method according to claim 1, wherein the wavelength of light absorbed by the nitrite nitrogen is 330 to 380 nm. Nitrite nitrogen concentration for monitoring the nitrite nitrogen concentration of treated water treated in a treatment tank that treats the treated water in the presence of microorganisms and performs biological nitrification / denitrification of the treated water A monitoring device,
A first absorbance measuring means for irradiating the water to be treated flowing into the treatment tank with light absorbed by nitrite nitrogen, and measuring absorbance to the light;
A second absorbance measuring means for irradiating the water to be treated treated in the treatment tank with light absorbed by nitrite nitrogen, and measuring absorbance to the light;
A third absorbance measuring means for irradiating the water to be treated flowing into the treatment tank with light which is not absorbed by nitrite nitrogen and absorbed by organic matter, and measures the absorbance to this light;
A fourth absorbance measuring means for irradiating the water to be treated treated in the treatment tank with light that is not absorbed by nitrite nitrogen and that is absorbed by organic matter, and measuring the absorbance of the light;
The absorbance measured by the first absorbance measuring means is corrected based on the absorbance measured by the third absorbance measuring means, and the absorbance measured by the second absorbance measuring means is measured by the fourth absorbance measuring means. Corrected based on the absorbance, and processed in the treatment tank based on the difference between the corrected absorbance measured by the first absorbance measuring means and the corrected absorbance measured by the second absorbance measuring means. And a calculating means for calculating a change in the concentration of nitrite nitrogen in the treated water.

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