JP5637748B2 - Water quality information calculation method and apparatus - Google Patents

Description

  The present invention relates to a water quality information calculation method and apparatus suitable for calculating the fluctuation of nitrogen state in a biological reaction tank.

  In the global warming problem, nitrous oxide generated from the sewage treatment process is regarded as a problem. Nitrogen monoxide gas has a greenhouse effect 310 times that of carbon dioxide, and corresponds to 10% of the greenhouse gas emissions of the entire sewage treatment plant. However, at present, the amount of generation is not controlled.

  Nitrous oxide gas is generated during the nitrogen removal process of the sewage treatment process. About the generation amount, a correlation with the amount of nitrite nitrogen is pointed out as described in [Non-patent Document 1]. In order to estimate and control the amount of nitrous oxide generated, it is an intermediate product of ammonia nitrogen and nitrate nitrogen in the nitrification reaction, and a slight amount of nitrate nitrogen and nitrogen gas in the denitrification reaction. It is necessary to estimate the amount of product nitrite nitrogen.

  For the estimation of the amount of each component in the sewage treatment process, as described in [Non-Patent Document 2], for example, a water quality information processing unit equipped with ASM, which is a standard activated sludge model proposed by the International Water Association, is used. It is done. As for the water quality information calculation processing device, for example, there are those described in [Patent Document 1] and [Patent Document 2].

  ASM consists of a reaction model matrix of multiple components involved in reaction processes such as the growth and decomposition of microorganisms, and a reaction rate equation that describes the reaction rate of each reaction process. Many factors such as half-saturation constant and reaction rate constant are involved. In standard ASM, in order to simplify the reproduction (calibration) of the actual measurement water quality by adjusting the coefficient of reaction rate, for example, nitrogen components related to nitrification / denitrification reaction are replaced with ammonia nitrogen and nitrogen oxide 2 It approximates the component.

  The nitrification reaction route in ASM is shown in Equation 1, and the denitrification reaction route is shown in Equation 2.

ここで、ＮＨ₄はアンモニア性窒素、ＮＯ_xは窒素酸化物、Ｎ₂は窒素ガスである。

Here, NH ₄ is ammoniacal nitrogen, NO _x is nitrogen oxide, and N ₂ is nitrogen gas.

The difficulty of calibration is that adjustment of one reaction rate coefficient affects the amount of a plurality of components. For example, when the calibration difficulty level is defined as the total number of components that the reaction rate coefficient adjustment affects, the reaction rate adjustment in Equation 1 affects the amount of NH ₄ , NO _x , and N _2. Given, the adjustment of the reaction rate of Equation ₂ affects the amount of NO _x and N ₂ , so the difficulty level is 5.

  Calibration at a difficulty level of 5 is easy. Because of its ease, a water treatment process simulator equipped with ASM has been able to reproduce many sewage treatment processes so far and has been used for simulation of operation support and design support.

  Most of the nitrogen oxides are nitrate nitrogen, and in ASM, the nitrogen component is the sum of ammonia nitrogen and nitrogen oxide alone. However, strictly speaking, nitrite nitrogen and dinitrogen monoxide (dissolved state) are contained in trace amounts. In order to estimate this, in the conventional technique [Patent Document 3], a necessary intermediate product is added. Here, nitrite nitrogen is added to the intermediate product of the nitrification reaction, and nitrite nitrogen and dinitrogen monoxide (dissolved state) are added as intermediate products of the denitrification reaction. The route of nitrification reaction is shown in Equation 3, and the route of denitrification reaction is shown in Equation 4.

ここで、ＮＯ₂は亜硝酸性窒素を、ＮＯ₃は硝酸性窒素を、Ｎ₂Ｏは一酸化二窒素を表す。硝化反応と還元反応において亜硝酸性窒素を求め、その亜硝酸性窒素から一酸化二窒素を推定する。一般的に一酸化二窒素の量は微量で、全窒素態の１％未満であるが、この方法では窒素収支に一酸化二窒素が含まれる。

Here, NO ₂ represents nitrite nitrogen, NO ₃ represents nitrate nitrogen, and N ₂ O represents dinitrogen monoxide. Nitrite nitrogen is obtained in the nitrification reaction and reduction reaction, and nitrous oxide is estimated from the nitrite nitrogen. Generally, the amount of dinitrogen monoxide is very small and less than 1% of the total nitrogen state, but this method includes dinitrogen monoxide in the nitrogen balance.

JP 2000-167585 A JP 2002-1370 A Japanese Patent Laid-Open No. 10-43787

Itokawa et al., “N2O Formation Mechanism under Organic Restriction in High Addition Intermittent Aeration Type Nitrification and Denitrification”, Environmental Engineering Research Papers, Vol. 34, pp.191-202 (1997) International Water Association, edited by task group on mathematical models to support the design and operation of biological wastewater treatment, “Activated Sludge Models ASM1, ASM2, ASM2d, ASM3”, Environmental Newspaper (2005)

  In the case of [Patent Document 3] described above, the number of components increases, and the number of components affected by each reaction also increases. As a result, since the calibration difficulty level is 18, the difficulty of calibration has been a practical problem.

  In addition, since there is no common reaction with Equations 1 and 2 that have been used in many calibrations, the coefficient values obtained by the previous calibration cannot be used, and there is a problem in that it takes time to recalibrate. It was. In addition, in order to suppress global warming, it is necessary to suppress dinitrogen monoxide gas. However, [Patent Document 1] does not describe the relationship between dinitrogen monoxide gas and dinitrogen monoxide (dissolved state). There was a problem that the amount of dinitrogen gas generated could not be predicted.

  An object of the present invention is to provide a water quality information calculation method and apparatus capable of visualizing water quality and greenhouse gas generated from a treatment plant, evaluating the amount of the calculated amount of dinitrogen monoxide gas, and examining its suppression means. Is to provide.

  In order to achieve the above object, the water quality information calculation method of the present invention is a water quality information calculation method for calculating reaction rates of a plurality of nitrogen components in a nitrification reaction with activated sludge, wherein the plurality of nitrogen components are: A first ammoniacal nitrogen, a nitrogen oxide, a second ammonia nitrogen, a nitrite nitrogen, and a nitrate nitrogen, wherein the first ammonia nitrogen is oxidized to the nitrogen oxide. The reaction rate is calculated using a model composed of one nitrification reaction path and a second nitrification reaction path in which the second ammoniacal nitrogen is oxidized to the nitrate nitrogen via the nitrite nitrogen. To do.

  The plurality of nitrogen components are nitrogen oxide, first nitrogen gas, nitrate nitrogen, nitrite nitrogen, and second nitrogen gas, and the nitrogen oxide is the first nitrogen gas. A first denitrification reaction path for reducing the nitrogenous nitrogen gas, and a second denitrification reaction path for reducing the nitrate nitrogen to the second nitrogen gas via the nitrite nitrogen. The reaction rate is calculated using a model.

  In addition, the plurality of nitrogen components include first ammonia nitrogen, nitrogen oxide, first nitrogen gas, second ammonia nitrogen, nitrite nitrogen, nitrate nitrogen, A first nitrification denitrification reaction path in which the first ammoniacal nitrogen is oxidized to the nitrogen oxide, and the nitrogen oxide is reduced to the first nitrogen gas, Second nitrification wherein the second ammonia nitrogen is oxidized to the nitrate nitrogen through the nitrite nitrogen, and the nitrate nitrogen is reduced to the second nitrogen gas through the nitrite nitrogen The reaction rate is calculated using a model composed of a denitrification reaction path.

  The water quality information calculation device of the present invention includes inflow condition setting means for setting the amount and quality of influent water, civil engineering structure setting means for setting the dimensions of the treatment process and the division of the biological reaction tank, pump flow rate and blower flow rate. The operation amount setting means for setting the water, the water quality calculation means for calculating the quality of the treated water in the biological reaction tank and the final sedimentation basin, and the display means, the display means from the power consumption of the pump and the blower The calculated amount of greenhouse gas emissions derived from electricity, the amount of greenhouse gas emissions calculated from the amount of nitrous oxide gas, the quality of the treated water obtained by the water quality information calculation method by the water quality calculation means, and The amount of nitrous oxide gas is displayed.

  According to the present invention, it is possible to visualize the water quality and greenhouse gas generated from the treatment plant, and it is possible to evaluate the calculated amount of nitrous oxide gas and to examine the suppression means.

The figure which shows the reaction path | route of Example 1 of this invention. The figure which shows the reaction path | route of Example 2 of this invention. The figure which shows the reaction path | route of Example 3 of this invention. The figure which shows the reaction path | route of Example 4 of this invention. The block diagram of the water quality simulator of Example 5 of this invention. The figure which shows the fluctuation graph of the water quality of Example 5. FIG. FIG. 6 shows a trend graph of dinitrogen monoxide in Example 5. The figure which shows the fluctuation | variation graph of the greenhouse gas of Example 5. FIG.

  Embodiments of the present invention will be described with reference to the drawings.

  FIG. 1 shows a reaction path of a plurality of nitrogen components in a model calculation means implemented in the water quality information calculation processing apparatus of Example 1 of the present invention. In this reaction path, the plurality of nitrogen components are first ammonia nitrogen 1, nitrogen oxide 2, second ammonia nitrogen 4, nitrite nitrogen 5, nitrate nitrogen 6.

  Reaction 10, reaction 11, and reaction 12 indicated by solid lines are nitrification reactions. Reaction 10 is an oxidation reaction of first ammoniacal nitrogen 1 to nitrogen oxide 2. Reaction 11 is an oxidation reaction of the second ammoniacal nitrogen 4 to nitrite nitrogen 5. Reaction 12 is an oxidation reaction of nitrite nitrogen 5 to nitrate nitrogen 6. These reactions occur at a certain reaction rate. For example, the reaction rate of the reaction 10 is a rate at which the first ammoniacal nitrogen 1 is changed to the nitrogen oxide 2.

  A reaction path 80, which is a first nitrification reaction path composed of the first ammoniacal nitrogen 1, nitrogen oxide 2, and reaction 10, is a reaction path of a standard activated sludge model ASM that has been conventionally used. In Example 1, in addition to the reaction path 80, a reaction path 81 which is a second nitrification reaction path composed of the second ammonia nitrogen 1, nitrogen nitrite 5, and nitrate nitrogen 6 is considered. Providing the reaction path 81 independently of the reaction path 80 corresponds to adding an intermediate product to the standard reaction path.

  In the first embodiment, the reaction path 81 is provided separately from the reaction path 80 in parallel, so that the coefficient of reaction rate adjusted in the reaction path 80 of the standard activated sludge model is affected. In addition, it is possible to provide model calculation means for obtaining a coefficient value for obtaining the amount of nitrite nitrogen 5.

  For example, first, based on the amounts of ammonia nitrogen and nitrogen oxides input as measured values or set values, the coefficients included in the reaction rate equation of the reaction 10 are adjusted so as to reproduce these amounts. Next, based on the amounts of ammonia nitrogen, nitrite nitrogen, and nitrate nitrogen input as measured values or set values, they are included in the reaction rate equations for Reaction 11 and Reaction 12 to reproduce these amounts. Adjust the coefficient. With the above procedure, it is possible to provide a model calculation means for obtaining a coefficient value for obtaining the amount of nitrite nitrogen 5 without affecting the coefficient value adjusted in the reaction path 80 of the standard activated sludge model.

  By using the method described below during the above-described procedure, the labor of calibration can be reduced, and an appropriate amount of nitrite nitrogen 5 can be obtained.

  This method makes the following assumptions. That is, the reaction rates of the reaction 10 and the reaction 11 are made equal, and the amounts of the first ammoniacal nitrogen and the second ammoniacal nitrogen are made equal.

The route of the nitrification reaction is represented by NH ₄ → NO ₂ → NO ₃ , but the amount of NO _{2 in} the intermediate product is generally small compared to NH ₄ and NO ₃ , so if a large time step is taken The decrease rate of NH ₄ and the increase rate of NO ₃ are about the same. Therefore, the reaction rate of the reaction 10 can be regarded as practically the same as the reaction rate of the reaction 11. Therefore, the reaction rate of reaction 10 and the reaction rate of reaction 11 are set to the same value. Since these reaction rates are equal, the amount of the reaction path 80 and the first ammoniacal nitrogen is equal to the amount of the second ammoniacal nitrogen of the reaction path 81, which can be regarded as the same component.

  Based on the above assumption, the difficulty during calibration can be reduced. In the reaction path 80 which is a standard activated sludge model, the number of components affected by the reaction rate adjustment of the reaction 10 is two, so the difficulty level is two.

  On the other hand, in the conventional technique in which the reaction path 81 is provided independently of the reaction path 80, the number of components affected by the reaction rate adjustment is 3 for reaction 11 and 2 for reaction 12. The difficulty level increases dramatically to 5.

  Since the amount of the second ammoniacal nitrogen 4 and the reaction rate 11 are determined in the calibration of the reaction path 80 based on the assumption of Example 1, the difficulty of calibration of the reaction rate 81 is On the other hand, with two components, the degree of difficulty by the method of Example 1 is 2 + 2 = 4, which can be made smaller than the degree of difficulty of the prior art.

  Further, nitrogen oxide 2, nitrite nitrogen 3 and nitrate nitrogen 4 are not mutually independent variables. In Example 1, the amount of nitrogen oxide 2 determined by a standard activated sludge model and the amount of nitrite nitrogen 3 determined to predict the amount of nitrous oxide generated are important. For this reason, the amount of nitrate nitrogen 4 is defined as a dependent variable by the relational expression (5).

ここで、窒素酸化物２の量は［ＮＯ_x］、亜硝酸性窒素３の量は［ＮＯ₂］、硝酸性窒素４の量は［ＮＯ₃］である。これにより、計算誤差の蓄積や他の反応プロセスの干渉により、上式の関係が成立しないという不合理を避けることができる。

Here, the amount of nitrogen oxide 2 is [NO _x ], the amount of nitrite nitrogen 3 is [NO ₂ ], and the amount of nitrate nitrogen 4 is [NO ₃ ]. Thereby, it is possible to avoid the unreasonable fact that the relationship of the above equation is not satisfied due to accumulation of calculation errors and interference of other reaction processes.

  An example of a reaction rate newly added to the reaction path 80 of the standard activated sludge model is shown below.

  Reaction 12 is an oxidation reaction and proceeds when oxygen is high. The reaction rate of Reaction 12 is shown in Equation 6.

ここで、［Ｏ₂］は酸素の量、Ｋ₁は反応速度定数、Ｋ₂，Ｋ₃は半飽和定数、Ｘ_Aは硝化菌の量である。

Here, [O ₂ ] is the amount of oxygen, K ₁ is the reaction rate constant, K ₂ and K ₃ are half-saturation constants, and X _A is the amount of nitrifying bacteria.

  As described above, according to the first embodiment, it is possible to solve the problem of difficulty in calibration in the related art. The reaction path 80 is a reaction path of a standard activated sludge model that has been used so far, and calibration may already be performed to determine a count value of the reaction rate. In that case, a count value relating to the reaction rate of the reaction 12 in the reaction path 81 may be determined, and the labor of calibration can be reduced.

  In this example, the reaction rate of the reaction 12 is represented by the Monod equation. However, other model equations may be used, and a discontinuous value depending on a constant or a case may be used. Further, these linear sums may be used. The variable component is not limited to the component shown here, and other components may be used.

  Since the process for determining the amount of nitrite nitrogen 3 in this embodiment is independent of the calculation process for determining ammonia nitrogen 1 and nitrogen oxide 2, not only the standard activated sludge model ASM but also the nitrification reaction It can be applied to any model that describes changes in the amount of components due to denitrification.

  In this example, in the process of determining the amounts of nitrite nitrogen 3 and nitrate nitrogen 4, the difficulty of calibration is reduced by first determining the reaction rate for nitrogen oxide 2, which is the combined amount of them. Although what can be said, the same method may be applied to other component A, component B, and component C which is the total amount of component A and component B having the same relationship.

  In this example, nitrite nitrogen was considered as an intermediate product, but a dissolved state of dinitrogen monoxide may be further added.

  In this embodiment, nitrite nitrogen is considered as an intermediate product of the nitrification process. However, it is not necessarily limited to nitrite nitrogen, and may be defined as a precursor of nitrous oxide gas. In this case, it is not necessary to reproduce the value input as an actual measurement or set value of nitrite nitrogen during calibration.

  FIG. 2 shows a reaction path of a plurality of nitrogen components in a model calculation means implemented in the water quality information calculation processing apparatus according to the second embodiment of the present invention. The plurality of nitrogen components are nitrogen oxide 2, first nitrogen gas 3, nitrite nitrogen 5, nitrate nitrogen 6, and second nitrogen gas 7.

  Reactions 13, 14, and 15 indicated by dotted lines are denitrification reactions. Reaction 13 is a reduction reaction of nitrogen oxide 2 to first nitrogen gas 3. Reaction 14 is a reduction reaction of nitrate nitrogen 6 to nitrite nitrogen 5. Reaction 15 is a reduction reaction of nitrite nitrogen 5 to second nitrogen gas 7. These reactions occur at a certain reaction rate. For example, the reaction rate of the reaction 13 is a rate at which the nitrogen oxide 2 is changed to the first nitrogen gas 3.

  A reaction path 90 which is a first denitrification reaction path constituted by the nitrogen oxide 2, the first nitrogen gas 3 and the reaction 13 is a reaction path of a standard activated sludge model ASM which has been conventionally used. . In Example 2, a reaction path 91 that is a second denitrification reaction path composed of nitrite nitrogen 5, nitrate nitrogen 6 and nitrogen gas 7 is considered separately from the reaction path 90. Providing this reaction path independently of the reaction path 90 corresponds to adding an intermediate product to the standard reaction path.

  In Example 2, the reaction path 91 is provided separately from the reaction path 90 in parallel, and the coefficient of the reaction rate adjusted in the reaction path 90 of the standard activated sludge model is affected. In addition, it is possible to provide model calculation means for obtaining a coefficient value for obtaining the amount of nitrite nitrogen 5.

  For example, first, based on the amounts of ammonia nitrogen and nitrogen oxides input as measured values or set values, the coefficients included in the reaction rate equation of the reaction 13 are adjusted so as to reproduce these amounts. Next, based on the amounts of nitrite nitrogen and nitrate nitrogen input as measured values or set values, the coefficients included in the reaction rate equations of Reaction 14 and Reaction 15 are adjusted to reproduce these amounts. To do. With the above procedure, it is possible to provide a model computing means for obtaining a coefficient value for obtaining the amount of nitrite nitrogen 5 without affecting the coefficient value adjusted in the reaction path 90 of the standard activated sludge model.

  By using the method described below during the above-described procedure, the labor of calibration can be reduced, and an appropriate amount of nitrite nitrogen 5 can be obtained.

  This method makes the following assumptions. The reaction rates of the reaction 13 and the reaction 15 are made equal, and the amounts of the first nitrogen gas and the second nitrogen gas are made equal.

In the denitrification route, NO ₂ is considered as an intermediate product. Dissolved dinitrogen monoxide N ₂ O is negligible in comparison with NO ₂ and is negligible because it is sufficiently small relative to the amount of total nitrogen. As a result, the route of the denitrification reaction is represented by NO ₃ → NO ₂ → N ₂ , but the amount of intermediate product NO ₂ is generally smaller than NO ₃ and N _2, and the time step is reduced. taking large, the rate of increase in decline rate and N ₂ of the NO ₃ are comparable. Therefore, the reaction rate of the reaction 13 can be regarded as practically the same as the reaction rate of the reaction 15. Therefore, in Example 2, the reaction rate of reaction 13 and the reaction rate of reaction 15 were set to the same value. Since these reaction rates are equal, the reaction path 90 and the reaction path 91 contain the same nitrogen gas 5.

  By assuming as described above, the difficulty level during calibration can be reduced. In the reaction path 90, which is a standard activated sludge model, the number of components affected by the reaction rate adjustment of the reaction 13 is two, so the difficulty level is two. In the prior art in which the reaction path 91 is provided independently of the reaction path 90, the number of components affected by the reaction rate adjustment is 3 for the reaction 14 and 2 for the reaction 15, and the difficulty is 5 And increase dramatically.

  Based on the assumption of this embodiment, the amount of the second nitrogen gas 7 and the reaction rate 13 are determined by calibration of the reaction path 90. Therefore, the difficulty of calibration of the reaction speed 91 is two components with respect to the reaction 14, and in this embodiment, the difficulty is 2 + 2 = 4, which can be smaller than the difficulty of the conventional technique.

  Further, nitrogen oxide 2, nitrite nitrogen 3 and nitrate nitrogen 4 are not mutually independent variables. In this embodiment, the amount of nitrogen oxide 2 determined by a standard activated sludge model and the amount of nitrite nitrogen 3 determined to predict the amount of nitrous oxide generated are important. Therefore, the amount of nitrate nitrogen 4 is defined by the above-described relational expression 5 as a dependent variable.

  Thereby, it is possible to avoid the unreasonable fact that the relationship of the above equation is not satisfied due to accumulation of calculation errors and interference of other reaction processes.

  The example of the reaction rate newly added with respect to the reaction path 90 of a standard activated sludge model is shown below.

  Since reaction 14 is a reduction reaction, it proceeds when oxygen is low. The reaction rate of Reaction 14 is shown in Equation 7.

ここで、Ｋ₄は反応速度定数、Ｋ₅，Ｋ₆は半飽和定数、Ｘ_Hは従属影響菌の量である。

Here, K ₄ is a reaction rate constant, K ₅ and K ₆ are half-saturation constants, and X _H is the amount of dependent effect bacteria.

  As described above, according to the present embodiment, the problem of the difficulty of calibration in the conventional technique can be solved. Further, the reaction path 90 is a reaction path of a standard activated sludge model that has been used so far, and calibration may already be performed to determine a reaction rate count value. In that case, a count value relating to the reaction rate of the reaction 14 in the reaction path 91 may be determined, and the labor of calibration can be reduced.

  In this example, the reaction rate of the reaction 14 is represented by the Monod equation, but other model equations may be used, and a discontinuous value depending on a constant or a case may be used. Further, these linear sums may be used. The variable component is not limited to the component shown here, and other components may be used.

  Since the process for obtaining the amount of nitrite nitrogen 3 in this embodiment is independent of the calculation process for obtaining the amounts of nitrogen oxide 2 and first nitrogen gas 3, it is not limited to the standard activated sludge model ASM. It can be applied to any model that describes changes in the amount of components due to nitrification and denitrification reactions.

  In this example, in the process of determining the amounts of nitrite nitrogen 3 and nitrate nitrogen 4, the difficulty of calibration is reduced by first determining the reaction rate for nitrogen oxide 2, which is the combined amount of them. Although described above, the same method may be applied to other component A, component B, and component C which is the combined amount of component A and component B having the same relationship.

  In this example, nitrite nitrogen was considered as an intermediate product, but a dissolved state of dinitrogen monoxide may be further added.

  In this embodiment, nitrite nitrogen is considered as an intermediate product of the nitrification / denitrification process. However, it is not necessarily limited to nitrite nitrogen, and may be defined as a precursor of nitrous oxide gas. In this case, it is not necessary to reproduce the value input as an actual measurement or set value of nitrite nitrogen during calibration.

  FIG. 3 shows reaction paths of a plurality of nitrogen components in the model calculation means implemented in the water quality information calculation processing apparatus according to the third embodiment of the present invention. The plurality of nitrogen components are: first ammonia nitrogen 1, nitrogen oxide 2, first nitrogen gas 3, second ammonia nitrogen 4, nitrite nitrogen 5, nitrate nitrogen 6, second nitrogen Nitrogen gas 7.

  Reaction 10, reaction 11, and reaction 12 indicated by solid lines are nitrification reactions. Reaction 10 is a first oxidation reaction of ammoniacal nitrogen 1 to nitrogen oxide 2. Reaction 11 is an oxidation reaction of second ammoniacal nitrogen 4 to nitrite nitrogen 5. Reaction 12 is an oxidation reaction of nitrite nitrogen 5 to nitrate nitrogen 6.

  Reactions 13, 14, and 15 indicated by dotted lines are denitrification reactions. Reaction 13 is a reduction reaction of nitrogen oxide 2 to first nitrogen gas 3. Reaction 14 is a reduction reaction of nitrate nitrogen 6 to nitrite nitrogen 5. Reaction 15 is a reduction reaction of nitrite nitrogen 5 to second nitrogen gas 7. These reactions have a reaction rate. For example, the reaction rate of the reaction 10 is a rate at which the first ammoniacal nitrogen 1 is changed to the nitrogen oxide 2.

  A reaction path 100 which is a first nitrification denitrification reaction path composed of first ammoniacal nitrogen 1, nitrogen oxide 2, first nitrogen gas 3, reaction 10, and reaction 13 has been conventionally used. This is a reaction path of a standard activated sludge model ASM.

  In this embodiment, in addition to the reaction path 100, a reaction path 101 that is a second nitrification / denitrification reaction path composed of the second ammoniacal nitrogen 1, nitrogen nitrite 5, nitrate nitrogen 6, and nitrogen gas 7. think of. Providing this reaction path independently of the reaction path 100 corresponds to the prior art when adding an intermediate product to the standard reaction path.

  In this embodiment, by providing the reaction path 101 in parallel with the reaction path 100 in addition to the reaction path 100, the coefficient value of the reaction rate adjusted in the reaction path 100 of the standard activated sludge model is affected. In addition, it is possible to provide model calculation means for obtaining a coefficient value for obtaining the amount of nitrite nitrogen 5.

  For example, first, based on the amounts of ammonia nitrogen and nitrogen oxides input as measured values or set values, the coefficients included in the reaction rate equations of Reaction 10 and Reaction 13 are adjusted to reproduce these amounts. To do. Next, based on the amounts of ammoniacal nitrogen, nitrite nitrogen, and nitrate nitrogen input as measured values or set values, reaction 11, reaction 12, reaction 14, and reaction 15 are reproduced so as to reproduce these amounts. The coefficient included in the reaction rate equation is adjusted. With the above procedure, it is possible to provide a model calculation means for obtaining a coefficient value for obtaining the amount of nitrite nitrogen 5 without affecting the coefficient value adjusted in the reaction path 100 of the standard activated sludge model.

  By using the method described below in the above-described procedure, the labor of calibration can be reduced, and an appropriate amount of nitrite nitrogen 5 can be obtained.

  In this method, the following assumptions are made. That is, the reaction rates of the reaction 10 and the reaction 11 are made equal, and the amounts of the first ammoniacal nitrogen and the second ammoniacal nitrogen are made equal. In addition, the reaction rates of the reaction 13 and the reaction 15 are made equal, and the amounts of the first nitrogen gas and the second nitrogen gas are made equal.

The route of the nitrification reaction is represented by NH ₄ → NO ₂ → NO ₃ , but the amount of NO _{2 in} the intermediate product is generally small compared to NH ₄ and NO ₃ , so if a large time step is taken The decrease rate of NH ₄ and the increase rate of NO ₃ are about the same. Therefore, the reaction rate of the reaction 10 can be regarded as practically the same as the reaction rate of the reaction 11. Therefore, the reaction rate of reaction 10 and the reaction rate of reaction 11 are set to the same value. Since these reaction rates are equal, the amount of the reaction path 100 and the first ammoniacal nitrogen is equal to the amount of the second ammoniacal nitrogen in the reaction path 101, and they are the same component.

In the route of denitrification reaction, NO ₂ is considered as an intermediate product. Dissolved dinitrogen monoxide N ₂ O is negligible in comparison with NO ₂ and is negligible because it is sufficiently small relative to the amount of total nitrogen. As a result, the route of the denitrification reaction is represented by NO ₃ → NO ₂ → N ₂ , but the amount of intermediate product NO ₂ is generally smaller than NO ₃ and N _2, and the time step is reduced. taking large, the rate of increase in decline rate and N ₂ of the NO ₃ are comparable. Therefore, the reaction rate of reaction 13 is practically the same as the reaction rate of reaction 15. Therefore, in Example 3, the reaction rate of reaction 13 and the reaction rate of reaction 15 were set to the same value. Since these reaction rates are equal, the reaction path 100 and the reaction path 101 contain the same nitrogen gas 5.

  Based on the above assumption, the difficulty during calibration can be reduced. The difficulty level of the reaction path 100 is 5. When the reaction path 101 is provided independently from the conventional technique, the number of components affected by the reaction rate adjustment is 4 for reaction 11, 3 for reaction 12, and 13 for reaction 13. 3 components, 2 components for reaction 15, and the difficulty increases dramatically to 12.

  Assuming the present embodiment, the amounts of the second ammonia nitrogen 4 and the second nitrogen gas 7, the reaction rate 11 and the reaction rate 15 are determined by the calibration of the reaction path 100. Therefore, the degree of difficulty in calibrating the reaction rate 101 is 4 in total, that is, 2 components for the reaction 12 and 2 components for the reaction 14, and the difficulty according to the method of this example is 5 + 4 = 9. Can be less than difficulty.

  Further, nitrogen oxide 2, nitrite nitrogen 3 and nitrate nitrogen 4 are not mutually independent variables. In this embodiment, the amount of nitrogen oxide 2 determined by a standard activated sludge model and the amount of nitrite nitrogen 3 determined to predict the amount of nitrous oxide generated are important. Therefore, the amount of nitrate nitrogen 4 is defined by the above-described relational expression 5 as a dependent variable.

  Thereby, it is possible to avoid the unreasonable fact that the relationship of the above equation is not satisfied due to accumulation of calculation errors and interference of other reaction processes.

  An example of a reaction rate newly added to the reaction path 100 of the standard activated sludge model is shown below. Reaction 12 is an oxidation reaction and proceeds when oxygen is high. The reaction rate of Reaction 12 is shown in Equation 6 above.

  Since reaction 14 is a reduction reaction, it proceeds when oxygen is low. The reaction rate of Reaction 14 is shown in Equation 7 above.

  As described above, the present embodiment can solve the problem of difficulty in calibration in the prior art. The reaction path 100 is a reaction path of a standard activated sludge model that has been used so far, and calibration may already be performed to determine a reaction rate count value. In that case, it is only necessary to determine the count value regarding the reaction rates of the reaction 12 and the reaction 14 in the reaction path 101, and the labor of calibration can be reduced.

  In this embodiment, the reaction rates of the reaction 12 and the reaction 14 are expressed by the Monod equation, but other model equations may be used, and a discontinuous value depending on a constant or a case may be used. Further, these linear sums may be used. The variable component is not limited to the component shown here, and other components may be used.

  Since the process for determining the amount of nitrite nitrogen 3 in this embodiment is independent of the calculation process for determining ammonia nitrogen 1 and nitrogen oxide 2, not only the standard activated sludge model ASM but also the nitrification reaction It can be applied to any model that describes changes in the amount of components due to denitrification.

  In the present embodiment, in the process of obtaining the amounts of nitrite nitrogen 3 and nitrate nitrogen 4, the difficulty of calibration can be alleviated by first obtaining the reaction rate relating to nitrogen oxide 2 which is the combined amount thereof. However, the same method may be applied to the component A, the component B, and the component C that is the combined amount of the component A and the component B having the same relationship.

  In Example 3, only nitrite nitrogen was considered as an intermediate product, but a dissolved state of dinitrogen monoxide may be further added.

  In this embodiment, nitrite nitrogen is considered as an intermediate product of the nitrification / denitrification process. However, it is not necessarily limited to nitrite nitrogen, and may be defined as a precursor of nitrous oxide gas. In this case, it is not necessary to reproduce the value input as an actual measurement or set value of nitrite nitrogen during calibration.

  FIG. 4 shows a reaction path of a plurality of nitrogen components in a model calculation means implemented in the water quality information calculation processing apparatus of Example 4 of the present invention. In this embodiment, the dinitrogen monoxide gas 8 is added to the reaction path 101 configured as in the first embodiment, and the reaction 16 from the nitrite nitrogen 5 to the dinitrogen monoxide gas 8 is added.

  The reaction rate of Reaction 16 is shown in Formula 8.

Since the amount of nitrite nitrogen 5 is related to the generation of nitrous oxide gas 8, the amount of nitrite nitrogen [NO ₂ ] was used as a variable. Here, K ₇ is a purge constant, which is 1 in an aerobic tank and 0 in an anaerobic tank. K ₈ is a reaction rate constant, and constant K ₉ is a half-saturation constant. X _A is the amount of nitrifying bacteria. The purge constant is a constant representing that N ₂ O is generated in the solution in a dissolved state and then released into the atmosphere by the purge effect of aeration.

In the prior art, the nitrous oxide gas 8 was used as an intermediate product of the denitrification reaction. However, since the amount of nitrous oxide 6 is extremely small, in Example 4, the final product generated from the nitrite nitrogen 5 is used. It was assumed that there was no change in the nitrite nitrogen 5 due to the generation of the dinitrogen monoxide gas 8. Thereby, the difficulty level of the calibration by the reaction 16 becomes 1. The degree of difficulty of the reaction path 101 after the difficulty level 5 of the reaction path 100 is 7 in total, 3 components for the reaction 12, 3 components for the reaction 14, and 1 component for the reaction 16. Example 2 The degree of difficulty in calibration by means of 5 + 7 = 12. This is smaller than the degree of difficulty 18 when the amount of N ₂ O in the conventional technique described in [Background Art] is also obtained, and calibration can be easily performed. In addition, in the prior art described in [Background Art], there was a problem that the method of obtaining the amount of nitrous oxide gas is unknown, but the amount of nitrous oxide gas produced is determined by the method of this example. Can do.

  In this example, the reaction rate of the reaction 16 is represented by the Monod equation, but other model equations may be used, and a discontinuous value depending on a constant or a case may be used. Further, these linear sums may be used. The variable component is not limited to the component shown here, and other components may be used.

  In this example, only nitrite nitrogen was considered as an intermediate product, but a dissolved state of dinitrogen monoxide may be further added.

  In this embodiment, nitrite nitrogen is considered as an intermediate product of the nitrification / denitrification process. However, it is not necessarily limited to nitrite nitrogen, and may be defined as a precursor of nitrous oxide gas. In this case, it is not necessary to reproduce the value input as an actual measurement or set value of nitrite nitrogen during calibration.

  FIG. 5 is a configuration diagram of a water quality simulator using the water quality information calculation method according to the fifth embodiment of the present invention. The water quality simulator 20 includes an inflow condition setting means 21 for setting the amount and quality (components) of inflow water, a civil engineering structure setting means 22 for setting the dimensions of the treatment process and the division of the biological reaction tank, a pump flow rate and a blower blast amount. The operation amount setting means 23 for setting the water and the water quality calculation means 24 for calculating the water quality value of the treated water in the biological reaction tank and the final sedimentation basin. The model calculation means 25 for calculating the nitrogen water quality value described in the first to fourth embodiments is included in the water quality calculation means 24. The result calculated by the water quality calculation means 24 is displayed on the display means 26.

  In this water quality simulator 20, for example, in a water treatment plant composed of a biological reaction tank for treating sewage by biological treatment with activated sludge and a final sedimentation basin, treated water with respect to the inflow conditions and operation amount of the water treatment plant. The calculation amount of water quality and the amount of nitrous oxide produced can be visualized.

  The inflow condition setting means 21 sets the inflow sewage amount and the concentration of the inflow water quality based on the actual value or the value input as the set value. The influent water quality here is organic matter, phosphorus, etc. in addition to the nitrogen state described in Example 1 or 2. The civil engineering structure setting means 22 sets the volume of the biological reaction tank and final sedimentation basin of the target water treatment plant, the number of divisions of the biological reaction tank, piping such as a circulation flow path, a return flow path, and a blower flow path. In the operation amount setting means, a pump flow rate such as a circulation flow rate and a return flow rate, and a blower air flow rate are set.

  Based on the data set as described above, the water quality calculation means 24 calculates the quality of the treated water in the biological reaction tank and the final sedimentation basin. For the water quality calculation means 24, the material balance equation shown in Equation 9 is used, which is obtained by adding the relationship between inflow and outflow in each tank (biological reaction tank and final sedimentation basin) to the standard activated sludge model described above.

ここで、Ｃ_i：対象とする槽での水質ｉの濃度、Ｃ_i,in：水質ｉの流入濃度、Ｃ_i,out：水質ｉの流出濃度、Ｖ：対象とする槽の容積である。ΔＣ_iは活性汚泥モデルにより演算される生物反応による（単位時間あたりの）濃度変化量である。なお、窒素態のΔＣ_iに関しては、本実施例のモデル演算手段で演算される。また、最終沈殿池では、固形物質と溶存物質の分離も演算する。

Here, C _{i is} the concentration of water quality i in the target tank, C _{i, in is} the inflow concentration of water quality i, C _{i, out is} the outflow concentration of water quality i, and V is the volume of the target tank. ΔC _i is a concentration change amount (per unit time) due to a biological reaction calculated by the activated sludge model. Note that the nitrogen-state ΔC _i is calculated by the model calculation means of the present embodiment. In the final sedimentation basin, the separation of solid and dissolved substances is also calculated.

  The amount of greenhouse gas generated from each biological reaction tank is calculated from the set power consumption of an electric motor such as a pump and a blower and the amount of nitrous oxide gas described in the fourth embodiment, using Equations 10 and 11. .

ここで、Ｇ_total：処理場全体からの全温室効果ガス排出量の二酸化炭素換算値、Ｇ_P：電動機の消費電力に由来する温室効果ガス排出量の二酸化炭素換算値、Ｇ_N2O：一酸化二窒素ガスに由来する温室効果ガス排出量の二酸化炭素換算値、Ｐ_j：電動機ｊの消費電力、Ｃ_k,N2O：生物反応槽ｋのＮ₂Ｏ排出量、ｍ：電動機数、ｎ：生物反応槽数、Ａ_P：電力の二酸化炭素換算係数、Ａ_N2O：一酸化二窒素ガスの二酸化炭素換算係数である。単位にもよるが、一般的には、Ａ_P＝０.５５５［kg−ＣＯ₂／ｋＷｈ］，Ａ_N2O＝３１０［kg−ＣＯ₂／kg−Ｎ₂Ｏ］が用いられる。

Here, G _total : carbon dioxide equivalent value of total greenhouse gas emissions from the entire treatment plant, _GP : carbon dioxide equivalent value of greenhouse gas emissions derived from power consumption of electric motor, _GN2O : dimonoxide Carbon dioxide equivalent value of greenhouse gas emissions derived from nitrogen gas, P _j : Power consumption of motor j, C _k, N ₂ O: N ₂ O emissions of biological reaction tank k, m: Number of motors, n: Biological reaction Number of tanks, A _P : carbon dioxide conversion coefficient of electric power, A _N2O : carbon dioxide conversion coefficient of dinitrogen monoxide gas. Although it depends on the unit, generally A _P = 0.555 [kg-CO ₂ / kWh], A _N2O = 310 [kg-CO ₂ / kg-N ₂ O] are used.

  The water quality of the treated water in the biological reaction tank and the final sedimentation basin calculated by the material balance equation considering the transport and reaction of water quality is visualized by the display means 26. The display means 26 outputs the calculation result to a PC monitor, for example, by means such as a bar graph, a trend graph, and a list.

  FIG. 6 shows changes in the concentrations of ammonia nitrogen, nitrate nitrogen and nitrite nitrogen, and changes in the production rate of dinitrogen monoxide gas in the biological reaction tank and the final sedimentation basin.

FIG. 7 shows a trend graph of nitrous oxide gas in a certain biological reaction tank. FIG. 8 shows changes in G _P , G _N2O and the total G _total at each time. By these, it becomes possible to visualize the amount of greenhouse gas and water discharged from the treatment plant.

  In addition, a function that searches on the water quality simulator for the conditions of the operation amount to suppress these based on the visualized water quality and greenhouse gas information can be added to the water quality simulator as a driving support function. good. At that time, an amount obtained by linearly combining the quality of the treated water and the greenhouse gas to be discharged with a certain weighting factor may be defined as an environmental cost, and the condition of the operation amount may be searched so as to minimize the environmental cost. . This weighting factor may be an input value.

  In addition to the above-mentioned electric power and dinitrogen monoxide gas, excess sludge and a flocculant may be added as a greenhouse gas emission source.

  As described above, the method of the present embodiment makes it possible to visualize the water quality and greenhouse gas generated from the treatment plant, and it is possible to evaluate the amount of the calculated nitrous oxide gas and to examine the suppression means. It becomes.

20 water quality simulator 21 inflow condition setting means 22 civil engineering structure setting means 23 operation amount setting means 24 water quality calculation means 25 model calculation means 26 display means

Claims (11)

In a water quality information calculation method for calculating reaction rates of a plurality of nitrogen components in a nitrification reaction by activated sludge,
The plurality of nitrogen components are first ammoniacal nitrogen, nitrogen oxides, second ammoniacal nitrogen, nitrite nitrogen, and nitrate nitrogen,
A first nitrification reaction pathway in which the first ammoniacal nitrogen is oxidized to the nitrogen oxides;
A second nitrification reaction pathway in which the second ammoniacal nitrogen is oxidized to the nitrate nitrogen via the nitrite nitrogen;
Calculate the reaction rate using a model in which a reaction from the nitrite nitrogen to nitrous oxide gas is added to the second nitrification reaction path,
Calculating the amount of nitrous oxide gas using the amount of nitrite nitrogen as a variable ,
The amount of the first ammoniacal nitrogen and the amount of the second ammoniacal nitrogen are made equal, the reaction rate from the first ammoniacal nitrogen to the nitrogen oxide, and the second ammoniacal nitrogen The water quality information calculation method characterized by equalizing the reaction rate to the nitrite nitrogen. 2. The water quality information calculation method according to claim 1, wherein, after the calculation of the reaction rate of the nitrogen component in the first nitrification reaction path, based on the input values of the amounts of the plurality of nitrogen components, the second The water quality information calculation method characterized by calculating the reaction rate of the nitrogenous component in the nitrification reaction path | route of water. In the water quality information calculation method according to claim 1 or 2 ,
A water quality information calculation method, wherein the amount of nitrate nitrogen is calculated as a difference between the amount of nitrogen oxide and the amount of nitrite nitrogen. In the water quality information processing unit that calculates the reaction rate of multiple nitrogen components in the denitrification reaction with activated sludge,
The plurality of nitrogen components are nitrogen oxide, first nitrogen gas, nitrate nitrogen, nitrite nitrogen, and second nitrogen gas, and the nitrogen oxide is the first nitrogen. A first denitrification pathway that reduces to gas,
A second denitrification reaction path in which the nitrate nitrogen is reduced to the second nitrogen gas via the nitrite nitrogen;
Calculate the reaction rate using a model in which a reaction from the nitrite nitrogen to nitrous oxide gas is added to the second nitrification reaction path,
Calculating the amount of nitrous oxide gas using the amount of nitrite nitrogen as a variable ,
The amount of the first nitrogen gas is equal to the amount of the second nitrogen gas, the reaction rate from the nitrogen oxide to the first nitrogen gas, and the nitrous nitrogen to the second nitrogen A water quality information calculation method characterized by equalizing the reaction rate to gas. The water quality information calculation method according to claim 4 ,
Based on the input values of the amounts of the plurality of nitrogenous components, after calculating the reaction rate of the nitrogenous components in the first denitrification reaction route, the nitrogenous components in the second denitrification reaction route A water quality information calculation method characterized by calculating a reaction rate. In the water quality information calculation method according to claim 4 or 5 ,
A water quality information calculation method, wherein the amount of nitrate nitrogen is calculated as a difference between the amount of nitrogen oxide and the amount of nitrite nitrogen. In the water quality information calculation method for calculating the reaction rate of multiple nitrogen components in the nitrification denitrification reaction with activated sludge,
The plurality of nitrogen components are first ammoniacal nitrogen, nitrogen oxide, first nitrogen gas, second ammoniacal nitrogen, nitrite nitrogen, nitrate nitrogen, Nitrogen gas, wherein the first ammoniacal nitrogen is oxidized to the nitrogen oxide, and the nitrogen oxide is reduced to the first nitrogen gas;
Second nitrification wherein the second ammonia nitrogen is oxidized to the nitrate nitrogen through the nitrite nitrogen, and the nitrate nitrogen is reduced to the second nitrogen gas through the nitrite nitrogen Denitrification reaction route,
Calculate the reaction rate using a model in which a reaction from the nitrite nitrogen to nitrous oxide gas is added to the second nitrification reaction path,
Calculating the amount of nitrous oxide gas using the amount of nitrite nitrogen as a variable ,
The amount of the first ammoniacal nitrogen and the amount of the second ammoniacal nitrogen are made equal, the reaction rate from the first ammoniacal nitrogen to the nitrogen oxide, and the second ammoniacal nitrogen The reaction rate to the nitrite nitrogen is made equal, the amount of the first nitrogen gas and the amount of the second nitrogen gas are made equal, and the reaction rate from the nitrogen oxide to the first nitrogen gas And the water quality information calculation method characterized by equalizing the reaction rate from the nitrite nitrogen to the second nitrogen gas. In the water quality information calculation method according to claim 7 ,
Based on the input values of the amounts of the plurality of nitrogenous components, after calculating the reaction rate of the nitrogenous components in the first nitrification / denitrification reaction route, A water quality information calculation method comprising calculating a reaction rate of a component. In the water quality information calculation method according to claim 7 or 8 ,
A water quality information calculation method, wherein the amount of nitrate nitrogen is calculated as a difference between the amount of nitrogen oxide and the amount of nitrite nitrogen. In the water quality information calculation method according to any one of claims 1 to 9 ,
A water quality information calculation method, wherein the amount of nitrous oxide gas is calculated using the amount of nitrogen nitrite as a variable. Inflow condition setting means for setting the amount and quality of the influent water, civil engineering structure setting means for setting the dimensions of the treatment process and division of the biological reaction tank, operation amount setting means for setting the pump flow rate and blower flow rate, Water quality calculation means for calculating the quality of treated water in the reaction tank and final sedimentation basin, and display means, and the display means includes greenhouse gas emissions derived from electric power calculated from power consumption of the pump and the blower. The amount of greenhouse gas emissions calculated from the amount of nitrous oxide gas and the quality of the treated water and the amount of nitrous oxide gas determined by the water quality calculation method according to claim 10 by the water quality calculation means Water quality information calculation device characterized by displaying.

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