JP5006849B2 - Denitrification method of organic raw water by controlling nitrite type nitrification - Google Patents

Description

  The present invention relates to a method for denitrifying organic raw water by controlling nitrite type nitrification.

Regarding a method for treating a nitrogen-containing liquid, an autotrophic denitrification is performed after a nitrite-type nitrification step in which a part of ammonia nitrogen (NH ₄ ⁺ ) in the nitrogen-containing liquid is oxidized to nitrite nitrogen (NO ₂ ⁻ ). By introducing an anaerobic ammonia oxidation reaction process (hereinafter referred to as “anammox process”) that utilizes microorganisms (hereinafter referred to as “anammox microorganisms”), the amount of aeration is reduced compared to conventional nitrification denitrification, methanol, etc. A technology for reducing the amount of organic matter added and reducing excess sludge is disclosed (Patent Document 1).

  Anammox microorganisms are a group of denitrifying microorganisms that can react with ammonia nitrogen as an electron donor and nitrite nitrogen as an electron acceptor under anaerobic conditions to generate nitrogen gas. An autotrophic denitrifying microorganism that does not require the addition of organic matter.

In the anammox process using the anaerobic ammonia oxidation reaction by anammox microorganisms, it is considered that ammonia nitrogen and nitrite nitrogen are decomposed into nitrogen gas (N ₂ ) by the following reaction.

That is, in order to efficiently perform denitrification in the anammox process, the content ratio of ammonia nitrogen and nitrite nitrogen in the water to be treated introduced into the anammox process is NO ₂ ⁻ / NH ₄ ⁺ = 0.57 / 0. It is desirable that .43 = 1.32. Regard the content of control, conventionally performs sampling before and after the nitrite type nitrification step as shown in FIG. 3, ammonia nitrogen concentration measuring device 2b nitrite type nitrification step before the ammonium nitrogen concentration C ₁ and after the step measuring the ammonium nitrogen concentration C _2, the following controls nitrite type nitrification rate in the nitrite-type nitrification step to follow the approximate expression (1), ammonia nitrogen and nitrite nitrogen to be introduced into anammox process A technique was adopted in which the content ratio was the content ratio (NO ₂ ⁻ / NH ₄ ⁺ = 0.57 / 0.43 = 1.32) (Patent Document 2).
NO ₂ ⁻ / NH ₄ ⁺ ≈ (C ₁ −C ₂ ) / C ₂ = 1.32 (1)

The above approximate expression (1) assumes that in the nitrite-type nitrification process, all of the oxidation of ammonia nitrogen remains in the nitrite nitrogen stage and is not oxidized to nitrate nitrogen and not reduced to nitrogen gas. the nitrate nitrogen concentration is to approximated by C ₁ -C _2.

However, if the water to be treated is organic raw water such as sewage and the BOD component coexists in the raw water, the oxidation reaction of nitrite nitrogen generated in the nitritation process further proceeds to denitrify (N ₂ ↑) It is known that reaction occurs and dinitrogen monoxide (N ₂ O ↑) is generated as a by-product of nitrification reaction or denitrification reaction (Patent Document 3).

Thus, when the nitrite type nitrification reaction and the gasification reaction coexist in the nitrification tank, the value represented by the molecule of the approximate expression (1) is {nitrite nitrogen (NO ₂ ⁻ ) concentration + nitrogen concentration ( N ₂ ) + Nitrous oxide concentration (N ₂ O)}, and a deviation from the actual nitrite nitrogen (NO ₂ ⁻ ) concentration occurs. Therefore, when the value is regarded as the nitrite nitrogen (NO ₂ ⁻ ) concentration and the control according to the approximate expression (1) is performed, a necessary amount of aeration is not performed and the nitrite nitrogen concentration becomes insufficient. .

As a result, the ammonia nitrogen (NH ₄ ⁺ ) concentration becomes excessive in the water to be introduced into the anammox process, unreacted ammonia nitrogen is generated in the anammox process, and ammonia nitrogen remains in the treated water. There was a problem.
JP 2003-33784 A JP 2006-88092 A JP 2001-179295 A

  The object of the present invention is to accurately control the concentration ratio of nitrite nitrogen and ammonia nitrogen in a method for treating a nitrogen-containing liquid consisting of a nitrite type nitrification process and an anammox process, so that ammonia nitrogen remains in the treated water. An object of the present invention is to provide a method for denitrification of organic raw water by controlling nitrite type nitrification so as not to occur.

The method for denitrifying organic raw water by controlling nitrite-type nitrification by controlling nitrite-type nitrification according to the present invention, which has been made to solve the above-mentioned problems, is to use organic raw water containing ammonia nitrogen in a nitrification tank. Introducing, a nitrite type nitrification step that oxidizes a part of ammonia nitrogen to nitrite nitrogen by the action of ammonia oxidizing bacteria, and introducing the effluent water from the nitrification tank into the anaerobic ammonia oxidation reaction tank, In the method for denitrifying organic raw water comprising an anaerobic ammonia oxidation reaction step of generating nitrogen gas by the action of autotrophic microorganisms using nitrite nitrogen as an electron acceptor and residual ammonia nitrogen as an electron donor, the concentration ratio of nitrite nitrogen and ammonia nitrogen in the water flowing out from the sub nitrification tank, and automatic sampling the effluent from the sub nitrification tank, the total nitrogen concentration measuring device and a Total nitrogen concentration and ammoniacal nitrogen concentration measured with a monia nitrogen concentration meter and the sum of organic nitrogen amount and nitrate nitrogen amount (α) or organic nitrogen concentration determined in advance according to the properties of organic raw water (organic nitrogen concentration ( and the nitrite type nitrification step is controlled so that the concentration ratio becomes a target value.

  The invention according to claim 2 is the method of denitrifying organic raw water by controlling nitrite type nitrification according to claim 1, wherein the concentration ratio of nitrite nitrogen to ammonia nitrogen is determined by {(total nitrogen concentration measured value). -Ammonia nitrogen concentration measurement value -α) / Ammonia nitrogen concentration measurement value}, where α is the sum of the amount of organic nitrogen and the amount of nitrate nitrogen determined in advance by the properties of the organic raw water. It is characterized by being.

The invention according to claim 3 is the method of denitrifying organic raw water by controlling the nitrite type nitrification according to claim 1, and further, the nitrate nitrogen concentration in the effluent water sampled is further converted into a nitrate nitrogen concentration measuring device. was measured by the concentration ratio of nitrite nitrogen and ammonia nitrogen, of {(total nitrogen concentration measurement - nitrate nitrogen concentration measurement-beta - ammonium nitrogen concentration measurement value) / ammonium nitrogen concentration measurement value} Calculated by the formula, β is the organic nitrogen concentration determined in advance by the properties of the organic raw water, and α is the amount of organic nitrogen and nitric acid determined in advance by the properties of the organic raw water It is the sum of the amount of sexual nitrogen.

The invention according to claim 4 is a nitrite type nitrification in which organic raw water containing ammonia nitrogen is introduced into a nitrification tank and a part of the ammonia nitrogen is oxidized to nitrite nitrogen by the action of ammonia oxidizing bacteria. And an effluent water from the nitrification tank is introduced into an anaerobic ammonia oxidation reaction tank, the nitrite nitrogen is used as an electron acceptor, and the remaining ammonia nitrogen is used as an electron donor by the action of autotrophic microorganisms. In an organic raw water denitrification method comprising an anaerobic ammonia oxidation reaction step for generating gas, the total nitrogen concentration and ammonia nitrogen concentration in the effluent from the nitrification tank are measured, and based on these measured values The nitrite-type nitrification process was controlled so that the calculated concentration ratio of nitrite nitrogen and ammonia nitrogen became a target value, and the concentration ratio was {(total nitrogen concentration measurement value−ammonia property). Nitrogen concentration measured value−α) / ammonia nitrogen concentration measured value} where α is the sum of the amount of organic nitrogen and the amount of nitrate nitrogen determined in advance by the properties of the organic raw water. It is a feature.

The invention according to claim 5 is a nitrite type nitrification in which organic raw water containing ammonia nitrogen is introduced into a nitrification tank and a part of the ammonia nitrogen is oxidized to nitrite nitrogen by the action of ammonia oxidizing bacteria. And an effluent water from the nitrification tank is introduced into an anaerobic ammonia oxidation reaction tank, the nitrite nitrogen is used as an electron acceptor, and the remaining ammonia nitrogen is used as an electron donor by the action of autotrophic microorganisms. In an organic raw water denitrification method comprising an anaerobic ammonia oxidation reaction step for generating gas, the total nitrogen concentration, ammonia nitrogen concentration and nitrate nitrogen concentration in the effluent from the nitrification tank are measured, and these The nitrite type nitrification process was controlled so that the concentration ratio of nitrite nitrogen calculated based on the measurement value and the ammoniacal nitrogen would be the target value, and the concentration ratio was {(total nitrogen concentration measurement Value−ammonia nitrogen concentration measurement value−nitrate nitrogen concentration measurement value−β) / ammonia nitrogen concentration measurement value}, where β is an organic nitrogen concentration determined in advance according to the properties of the organic raw water It is characterized by being.

The invention according to claim 6 is a target of the concentration ratio of nitrite nitrogen to ammonia nitrogen in the method for denitrification of organic raw water by controlling nitrite type nitrification according to any one of claims 1, 4 and 5. The value is characterized in that nitrite nitrogen concentration: ammonia nitrogen concentration = 0.57: 0.43.

A seventh aspect of the present invention provides a method for denitrifying organic raw water by controlling nitrite type nitrification according to any one of claims 1, 4 and 5, wherein the control of the nitrite type nitrification step is performed in a nitrification tank. This is performed by controlling the amount.

The invention according to claim 8 is characterized in that in the method for denitrifying organic raw water by controlling nitrite type nitrification according to any one of claims 1, 4 and 5, the autotrophic microorganism is anammox. Is.

  In the method for denitrification of organic raw water by controlling nitrite type nitrification according to the present invention, the total nitrogen concentration and ammonia nitrogen concentration in the effluent from the nitrification tank are measured, and the sublimation calculated based on these measured values is measured. By controlling the nitrite type nitrification step so that the concentration ratio of nitrate nitrogen and ammonia nitrogen becomes a target value, the conventional problem that ammonia nitrogen remains in the treated water can be solved.

  In the case of the above control, the following α is the sum of the amount of organic nitrogen and the amount of nitrate nitrogen determined in advance according to the properties of the organic raw water, and the concentration ratio of nitrite nitrogen and ammonia nitrogen is {(total nitrogen concentration measurement) The control accuracy can be improved by calculating according to the formula of value−ammonia nitrogen concentration measurement value−α) / ammonia nitrogen concentration measurement value}.

  In order to further improve the control accuracy, measurement of nitrate nitrogen concentration in the effluent from the nitrification tank was also added, and the following β was determined as the amount of organic nitrogen determined in advance by the nature of the organic raw water, and nitrite properties The concentration ratio of nitrogen and ammonia nitrogen is preferably calculated by the formula {(total nitrogen concentration measurement value−ammonia nitrogen concentration measurement value−nitrate nitrogen amount measurement value−β) / ammonia nitrogen concentration measurement value}. .

  By introducing the effluent water controlled by the present invention to the denitrification tank, the advantages specific to the anammox reaction such as an increase in the reaction rate of the anammox reaction and a reduction in the required amount of oxygen can be made more remarkable.

(First embodiment)
FIG. 1 is a block diagram showing an example of an apparatus suitable for carrying out the present invention. In FIG. 1, 1 is a nitrification tank used in a nitrite type nitrification process, 2a is a total nitrogen concentration measuring device, 2b is an ammonia nitrogen concentration measuring device, and 3 is an anaerobic ammonia oxidation reaction tank used in an anammox process.

  In the nitrification tank 1, air is supplied from the aeration device 6 provided at the bottom to the organic raw water introduced. A carrier 5 carrying ammonia-oxidizing bacteria is dispersed in the nitrification tank 1. Here, the organic raw water refers to, for example, sewage or the like, in which the BOD component coexists in the raw water. Ammonia-oxidizing bacteria are bacteria used for nitritation of ammoniacal nitrogen, and promote the following reaction (chemical formula 2) under aerobic conditions. In order to maintain an aerobic state suitable for the following reaction, the oxygen supply amount from the aeration apparatus 6 is adjusted.

  However, in fact, in the nitrification tank 1, in addition to the above reaction (Chemical formula 2), various reactions that generate nitrogen gas, nitrogen dioxide gas, ammonia gas and nitrate nitrogen also occur. In the method of adding 0.85 mol of oxygen to 1 mol of ammonia nitrogen in organic raw water, there is a problem that 0.57 mol of nitrite nitrogen and 0.43 mol of ammonia nitrogen cannot be obtained. . The content ratio of nitrite nitrogen: ammonia nitrogen = 0.57 mol: 0.43 mol is a content ratio suitable for the denitrification reaction by anaerobic ammonia oxidizing bacteria in the subsequent anammox process.

In the present invention, the outflow water 4 from the nitrification tank 1 is automatically sampled as the above problem solving means, and the total nitrogen concentration and ammonia nitrogen are measured by the total nitrogen concentration measuring device 2a and the ammonia nitrogen (NH ₄ ⁺ ) concentration measuring device 2b. Concentration is measured, and these measured value data are transmitted to the control device 7, and the progress of the reaction (Chemical Formula 2) is performed with the content ratio suitable for the anaerobic ammonia oxidation reaction in the subsequent Anammox process in the control device 7. Means for adjusting are provided.

  In the control device 7, the total nitrogen concentration and the ammonia nitrogen concentration of the effluent 4 transmitted from the total nitrogen concentration measuring device 2a and the ammonia nitrogen concentration measuring device 2b are determined by {(total nitrogen concentration measurement value−ammonia nitrogen concentration measurement). Substituting into the equation (value−α) / ammonia nitrogen concentration measurement value}, the control is performed so that the target value of the value is 0.57 / 0.43. Specifically, for example, when the numerator of the target value is smaller than 0.57, control is performed to increase the oxygen supply amount of the aeration apparatus 6 in order to increase the nitrite nitrogen concentration ratio in the effluent, The progress of the reaction (Chemical Formula 2) is promoted. On the other hand, when the numerator of the target value is larger than 0.57, control is performed to suppress the oxygen supply amount of the aeration apparatus 6 in order to increase the ammonia nitrogen concentration ratio in the effluent.

  Note that α used in the above equation is the sum of the amount of organic nitrogen and the amount of nitrate nitrogen determined in advance according to the properties of the organic raw water, and the value measured for the sample sampled in advance is the control device 7. Is the constant entered in. Since the α value varies depending on the properties of the organic raw water, when the properties of the organic raw water fluctuate, the control accuracy of the control device 7 is improved by changing the α value setting accordingly. be able to.

(Second Embodiment)
FIG. 2 is a block diagram showing an example of an apparatus suitable for the second embodiment. In the second embodiment, a nitrate nitrogen (NO ₃ ⁻ ) concentration measuring device 2c is further provided in the first embodiment. The adjustment of the oxygen supply amount in the second embodiment is carried out by measuring each concentration using the total nitrogen concentration measuring device 2a, the ammonia nitrogen concentration measuring device 2b, and the nitrate nitrogen concentration measuring device 2c, and transmitting it to the control device 7. In the control device 7, the total nitrogen concentration and the ammonia nitrogen concentration in the effluent water are expressed as {(total nitrogen concentration measurement value−ammonia nitrogen concentration measurement value−nitrate nitrogen amount measurement value−β) / ammonia nitrogen concentration measurement value. } Is substituted into the expression, and control is performed so that the target value of the value is 0.57 / 0.43.

  Note that β used in the above equation is the amount of organic nitrogen determined in advance according to the properties of the organic raw water, and is a constant obtained by inputting a value measured for a sample sampled in advance to the control device. Since the β value varies depending on the properties of the organic raw water, when the property of the organic raw water varies, the control accuracy of the control device 7 is improved by changing the setting of the β value accordingly. be able to.

  In the second embodiment, the measurement item of the effluent water is the total nitrogen concentration, ammonia nitrogen concentration, and nitrate nitrogen concentration, so that the oxygen supply amount corresponding to slight nitrate nitrogen concentration fluctuations in the effluent water can be obtained. Adjustment is possible and control accuracy is improved.

(Example)
The denitrification reaction using the apparatus suitable for carrying out the present invention shown in FIG. 1 is performed, and the total nitrogen concentration, organic nitrogen content, and ammonia nitrogen concentration in the nitrification tank 1 and the anaerobic ammonia oxidation tank 3 The results of measuring the amounts of nitrite nitrogen are shown in Table 1 below.

(Comparative example)
Table 2 below shows the results of performing the same denitrification reaction of the raw water as in the previous example using the apparatus used in the conventional method shown in FIG.

  In the prior art shown in (Table 2), the ammoniacal nitrogen concentration in the anaerobic ammonia oxidation reaction tank is 93 mg / L, whereas the ammoniacality in the anaerobic ammonia oxidation reaction tank of the present invention shown in (Table 1). The nitrogen concentration was significantly reduced to 6.4 mg / L, and the problem that ammonia nitrogen remained in the treated water was solved by the present invention. In addition, according to the present invention, the denitrification rate (92%) is also improved compared to the prior art (84%).

It is a block diagram which shows an example of an apparatus suitable for implementing this invention. It is a block diagram which shows an example of an apparatus suitable for 2nd Embodiment. It is a block diagram which shows an example of the apparatus used for implementation of the conventional method.

Explanation of symbols

1 Nitrification tank 2a Total nitrogen concentration meter 2b Ammonia nitrogen (NH ₄ ⁺ -N) concentration meter 2c Nitrate nitrogen (NO ₃ ^-- N) concentration meter 3 Anaerobic ammonia oxidation tank 4 Nitrification tank effluent
5 Carrier
6 Aeration equipment
7 Control unit

Claims (8)

A nitrite-type nitrification step in which organic raw water containing ammonia nitrogen is introduced into a nitrification tank, and a part of the ammonia nitrogen is oxidized to nitrite nitrogen by the action of ammonia oxidizing bacteria,
The effluent from the nitrification tank is introduced into an anaerobic ammonia oxidation reaction tank, and nitrogen gas is generated by the action of autotrophic microorganisms using the nitrite nitrogen as an electron acceptor and the remaining ammonia nitrogen as an electron donor. In the method of denitrifying organic raw water comprising an anaerobic ammonia oxidation reaction step,
The concentration ratio of nitrite nitrogen and ammoniacal nitrogen in the effluent from the nitrification tank,
The effluent water from the nitrification tank is automatically sampled and determined in advance according to the total nitrogen concentration and ammonia nitrogen concentration measured by the total nitrogen concentration measuring device and the ammonia nitrogen concentration measuring device, and the properties of the organic raw water. Calculated based on the sum of organic nitrogen and nitrate nitrogen (α) or organic nitrogen concentration (β) ,
A method for denitrifying organic raw water by controlling nitrite type nitrification, wherein the nitrite type nitrification step is controlled so that the concentration ratio becomes a target value. The concentration ratio of nitrite nitrogen and ammonia nitrogen is calculated by the formula {(total nitrogen concentration measurement value−ammonia nitrogen concentration measurement value−α) / ammonia nitrogen concentration measurement value},
2. The denitrification of organic raw water by controlling nitrite type nitrification according to claim 1, wherein α is the sum of the amount of organic nitrogen and the amount of nitrate nitrogen determined in advance according to the properties of the organic raw water Method. Furthermore, the nitrate nitrogen concentration in the automatically sampled effluent is measured with a nitrate nitrogen concentration meter, and the concentration ratio of nitrite nitrogen and ammonia nitrogen is determined by {(total nitrogen concentration measurement value−ammonia nitrogen concentration measurement). Value−nitrate nitrogen concentration measurement value−β) / ammonia nitrogen concentration measurement value}
2. The method of denitrifying organic raw water by controlling nitrite type nitrification according to claim 1, wherein β is an organic nitrogen concentration determined in advance according to the properties of the organic raw water. A nitrite-type nitrification step in which organic raw water containing ammonia nitrogen is introduced into a nitrification tank, and a part of the ammonia nitrogen is oxidized to nitrite nitrogen by the action of ammonia oxidizing bacteria,
The effluent from the nitrification tank is introduced into an anaerobic ammonia oxidation reaction tank, and nitrogen gas is generated by the action of autotrophic microorganisms using the nitrite nitrogen as an electron acceptor and the remaining ammonia nitrogen as an electron donor. In the method of denitrifying organic raw water comprising an anaerobic ammonia oxidation reaction step,
The total nitrogen concentration and ammonia nitrogen concentration in the effluent water from the nitrification tank are measured, and the concentration ratio of nitrite nitrogen calculated based on these measured values and the ammonia nitrogen concentration is set to a target value. Control the nitrite type nitrification process,
The concentration ratio is calculated by the equation {(total nitrogen concentration measurement value−ammonia nitrogen concentration measurement value−α) / ammonia nitrogen concentration measurement value}.
α is the sum of the amount of organic nitrogen and the amount of nitrate nitrogen determined in advance according to the properties of the organic raw water
Denitrification method of organic raw water by controlling nitrite type nitrification. A nitrite-type nitrification step in which organic raw water containing ammonia nitrogen is introduced into a nitrification tank, and a part of the ammonia nitrogen is oxidized to nitrite nitrogen by the action of ammonia oxidizing bacteria,
The effluent from the nitrification tank is introduced into an anaerobic ammonia oxidation reaction tank, and nitrogen gas is generated by the action of autotrophic microorganisms using the nitrite nitrogen as an electron acceptor and the remaining ammonia nitrogen as an electron donor. In the method of denitrifying organic raw water comprising an anaerobic ammonia oxidation reaction step,
The total nitrogen concentration, ammonia nitrogen concentration and nitrate nitrogen concentration in the effluent water from the nitrification tank are measured, and the concentration ratio of nitrite nitrogen calculated based on these measured values and the ammonia nitrogen concentration is the target. Control the nitrite type nitrification process so that
The concentration ratio is calculated by the formula {(total nitrogen concentration measurement value−ammonia nitrogen concentration measurement value−nitrate nitrogen concentration measurement value−β) / ammonia nitrogen concentration measurement value}.
A method of denitrifying organic raw water by controlling nitrite type nitrification, wherein β is an organic nitrogen concentration determined in advance according to the properties of the organic raw water. Target value of the concentration ratio of nitrite nitrogen and ammonia nitrogen, nitrite nitrogen concentration ammonium nitrogen concentration = 0.57: any claim 1,4,5, characterized in that 0.43 denitrification method of organic raw water by the control of the nitrite type nitrification according to any. 6. The denitrification of organic raw water by controlling nitrite type nitrification according to claim 1, wherein the nitrite type nitrification step is controlled by controlling the amount of aeration in the nitrite tank. Method. The method for denitrifying organic raw water by controlling nitrite type nitrification according to any one of claims 1, 4, and 5 , wherein the autotrophic microorganism is anammox.

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