JP2015054271A - Effluent treatment apparatus and effluent treatment method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To realize, on an occasion for treating nitrogen-containing water through a plurality of reaction tanks of an identical style connected in parallel, a treatment precision similar to that of a case where expensive nitric acid meters and/or ammonia meters are used without using the nitric acid meters and/or ammonia meters within all reaction tanks.SOLUTION: Nitrogen-containing water is fed through a plurality of reaction tanks at an identical flow rate, and not only is aeration controlled within a zone of any of the plurality of reaction tanks including an upstream zone on the basis of results of measurements by a nitric acid meter configured at a first specified position of the reaction tank and by an ammonia meter configured at a second specified position on the downstream side of the first in such a way that optimal denitrification and nitrification will be executed within the corresponding reaction tank but aeration levels of the other reaction tanks are also controlled by setting, based on the dissolved oxygen content measured at a specified position of the corresponding reaction tank, the goal value of the dissolved oxygen content at an identical position of the other reaction tanks.

Description

  The present invention relates to a nitrogen-containing water treatment device, a nitrogen-containing water treatment method, a nitrogen-containing water treatment system, a control device, a control method, and a program that control the amount of aeration air in an aerobic tank.

  Conventionally, as a sewage treatment system for treating sewage such as domestic nitrogen-containing water or factory nitrogen-containing water, various sewage treatment systems such as those using a standard activated sludge method and those using a trickling filter method have been put into practical use.

  In the sewage treatment system based on the standard activated sludge method, aeration treatment is performed in which oxygen is supplied to various types of aerobic microorganisms existing in the reaction tank while flowing the sewage to be treated into the reaction tank. As a result, the organic matter contained in the sewage in the reaction tank is decomposed by the action of the aerobic microorganism, and a stable treated water quality is obtained.

In the aeration process in the reaction tank, inflow water proportional control, DO (dissolved oxygen) control, or ammonia control (see Patent Document 1) is performed on the diffuser that performs aeration. The inflow water proportional control is a control for supplying an amount of air proportional to the amount of inflow water flowing into the reaction tank to the air diffuser using a flow meter installed on the inflow side of the reaction tank. The DO control measures the dissolved oxygen concentration using a dissolved oxygen meter (DO meter) installed at the end on the outflow side of the reaction tank, and supplies air to the air diffuser so as to maintain this dissolved oxygen concentration at a predetermined concentration. This is the supply control. Ammonia control uses an ammonia meter installed at the end on the outflow side of the reaction tank to supply air to the diffuser so that ammonia nitrogen (NH ₄ -N) at the end of the reaction tank is maintained at a predetermined concentration. It is control to do.

However, the various controls described above have the following problems.
That is, in the influent water proportional control, the organic matter load and ammonia load of the influent water containing nitrogen changes, and the water quality fluctuates. Therefore, if the air amount is controlled in proportion to the influent water amount, excess or deficiency of the air amount occurs. End up. In addition, in the DO control, the organic load and ammonia load of the inflowing water containing nitrogen change, and when these loads decrease, the air volume tends to become excessive, and conversely, when the load increases, the air volume is insufficient. It becomes easy to do. Furthermore, in the ammonia control, an appropriate amount of air can be supplied to the aeration device according to the ammonia load of the inflowing water containing nitrogen, but it is possible to control the denitrification process in the previous stage of performing the ammonia control. It was difficult.

  In order to solve the above-mentioned problems, the present inventors have nitrified ammonia in nitrogen-containing water into nitric acid according to the flow of nitrogen-containing water in the reaction tank, and at each position along the flow direction of nitrogen-containing water, A diffuser for supplying gas over substantially the entire area of the flow direction with respect to the nitrogen-containing water so that each desired ratio is denitrified, and a first predetermined position in the flow direction of the nitrogen-containing water, Denitrification confirmation means for confirming whether or not a desired ratio of nitric acid generated at the first predetermined position has been denitrified, and a second predetermined downstream of the denitrification confirmation means along the flow direction of the nitrogen-containing water According to the ratio of nitric acid generated by nitrification at the first predetermined position confirmed by the denitrification confirmation means, and the nitrification confirmation means for confirming whether or not the desired ratio of ammonia is nitrified. Nitrogen so that the desired proportion of nitric acid is denitrified While controlling the gas supply amount by the air diffuser at least upstream from the denitrification confirmation means along the flow direction of the water, according to the ratio of ammonia in the second predetermined position confirmed by the nitrification confirmation means, Nitrogen provided with gas supply amount control means for controlling the supply amount of gas from the aeration means at least upstream from the nitrification confirmation means along the flow direction of the nitrogen-containing water so that a desired ratio of ammonia is nitrified A treatment apparatus and a treatment method for water were proposed (Patent Document 2).

  According to the treatment apparatus and treatment method for nitrogen-containing water described above, the gas supply amount (aeration amount) is appropriately controlled according to the load of nitrogen-containing water flowing into the reaction tank that performs aeration, so that it is appropriate for the reaction tank. An amount of oxygen can be supplied, the denitrification treatment and the nitrification treatment can be appropriately controlled, the nitrogen removal rate can be improved, and the quality of the treated water can be improved.

  However, in sewage treatment facilities containing nitrogen due to various circumstances, it is often the case that a plurality of reaction tanks of the same type are connected in parallel and used in such facilities. It was necessary to provide denitrification confirmation means and nitrification confirmation means in addition to the aeration means in the reaction tank. Here, since the ammonia detector and the nitric acid detector used as the denitrification confirmation means and the nitrification confirmation means are expensive, there is a problem that the initial investment and maintenance of the equipment are expensive.

  Therefore, it is conceivable to use a relatively inexpensive dissolved oxygen meter (DO meter) instead of an expensive ammonia detector or nitric acid detector. However, a dissolved oxygen meter does not directly detect ammonia or nitric acid. Therefore, there is a problem that the aeration means cannot be controlled with high accuracy, and over-aeration occurs or it is difficult to achieve a desired water quality with high reliability.

Patent Document 1: Japanese Patent Application Laid-Open No. 2005-199116 Patent Document 2: Japanese Patent Application No. 2012-057883

  When the present inventor uses an ammonia detector or a nitric acid detector to control the aeration means so that appropriate denitrification and nitrification are performed, the dissolved oxygen amount in the reaction tank has a specific distribution. Attention has been paid to the present invention.

The nitrogen-containing water treatment apparatus of the present invention is as follows.
(1) a plurality of reaction tanks of the same type connected in parallel;
Flow rate control means for controlling the flow rate of nitrogen-containing water flowing into each reaction tank to be the same;
In each reaction tank, ammonia contained in the nitrogen-containing water is nitrified into nitric acid according to the flow of nitrogen-containing water, and each desired ratio of nitric acid is denitrified at each position along the flow direction of the nitrogen-containing water. Aeration means for supplying gas over substantially the entire region of the flow direction to the nitrogen-containing water,
An upstream denitrification section for obtaining a minimum amount of denitrification nitrogen along the flow direction of the nitrogen-containing water in any one of the plurality of reaction tanks, and the upstream denitrification section Is provided at a first predetermined position between the downstream nitrification section for obtaining the finally required nitrified water quality connected to the downstream side of the first nitrile, and a desired ratio of nitric acid is denitrified at the first predetermined position. Denitrification confirmation means for confirming the denitrification state of whether or not
Whether or not a desired proportion of ammonia is nitrified at the second predetermined position, which is provided downstream of the downstream nitrification section of the reaction tank provided with the denitrification confirmation means. Nitrification confirmation means for confirming the nitrification state;
Based on the denitrification state confirmed by the denitrification confirmation means, the denitrification along the flow direction of the nitrogen-containing water so that a desired ratio of the nitric acid is denitrified at the first predetermined position. The amount of gas supplied by the air diffuser is controlled in the section where the air diffuser is controlled by the denitrifier confirmer including at least the upstream side of the nitrogen confirmer, and confirmed by the nitrification confirmer. Control of aeration means due to the denitrification confirmation means along the flow direction of the nitrogen-containing water so that a desired ratio of the ammonia is nitrified at the second predetermined position based on the nitrification state In the section in which the control of the aeration means caused by the nitrification confirmation means is performed, which is the section following the section where the nitrification confirmation means is included. A first gas supply amount control means for controlling the supply amount of that gas,
Same as the first predetermined position in each reaction tank in the section where the control of the air diffuser due to the denitrification confirming means except the section until the air diffuser effect is exhibited by the air diffuser. The third predetermined position corresponding to the first predetermined position and the same position as the second predetermined position in the section in which the aeration means due to the nitrification confirmation means is controlled or Means for measuring the amount of dissolved oxygen in the nitrogen-containing water at different positions and corresponding to the second predetermined position, respectively, at the third predetermined position and the fourth predetermined position; ,
Based on the respective dissolved oxygen amounts measured at the third predetermined position and the fourth predetermined position of the reaction tank provided with the denitrification confirmation means and the nitrification confirmation means, the denitrification confirmation means and the nitrification confirmation Means for setting a dissolved oxygen target concentration at each of the third predetermined position and the fourth predetermined position in a reaction tank other than the reaction tank provided with the means;
The denitrification of the reaction tank so that the measured value of dissolved oxygen in the third predetermined position of the reaction tank other than the reaction tank provided with the denitrification confirmation means and the nitrification confirmation means matches the target concentration. A reaction tank other than the reaction tank provided with the denitrification confirmation means and the nitrification confirmation means, as well as controlling the gas supply amount by the aeration means in the section in which the control of the aeration means due to the confirmation means is performed The measured value of the dissolved oxygen at the fourth predetermined position of the reaction tank is controlled so that the gas diffused by the air diffuser is controlled in the section where the air diffuser is controlled by the nitrification confirmation device of the reaction tank. A second gas supply amount control means for controlling the supply amount;
It is characterized by providing.

  In the present invention, the “upstream denitrification section” means (1) an environmental state in which the amount of dissolved oxygen contained in the nitrogen-containing water gradually becomes rich in the reaction tank from the upstream side toward the downstream side. Assuming that such an environmental condition is a prerequisite, if it can be confirmed that the desired ratio of nitric acid is denitrified at a midpoint in the flow direction of the nitrogen-containing water, the desired concentration of nitric acid can be determined upstream from the midpoint. It can be estimated that the section in which the ratio is denitrified can be continuously secured, and (2) the length of the continuous section in which the desired ratio of nitric acid is denitrified upstream from the intermediate position becomes longer. The amount of denitrified nitrogen that follows and denitrifies to the middle position is increased, (3), and once the desired proportion of nitric acid is denitrified, it is released into the atmosphere. The resulting nitrogen molecule is again nitrogen Denitrification confirmed by denitrification confirmation means installed in a position in the reaction tank along the flow direction of nitrogen-containing water, which is determined in view of not returning to the water. When the amount of gas supplied by the air diffuser is controlled so that the desired denitrification state upstream of the installation position is maintained based on the state, the minimum amount of denitrification nitrogen can be obtained. , Section (81 in FIG. 1A). As described above, the “upstream denitrification section” is a section in which the denitrification state is confirmed by the denitrification confirmation means, and the nitrification reaction occurs also in this section.

  In addition, the “downstream nitrification section” is a section in the reaction tank along the flow direction of the nitrogen-containing water, and is based on the denitrification state confirmed by the denitrification confirmation means installed immediately before the section. The amount of dissolved oxygen contained in the nitrogen-containing water from the upstream side to the downstream side when the gas supply amount by the aeration means is controlled so that the desired denitrification state upstream from the installation position is maintained. This refers to a section (82 in FIG. 1A) in which it is expected that the necessary nitrified water quality will be finally obtained in combination with the environmental conditions in the reaction tank gradually becoming richer. As described above, the “downstream nitrification section” is a section where the nitrification state is confirmed by the nitrification confirmation means, and the denitrification reaction also occurs in this section.

  In the present invention, `` interval until the aeration effect is manifested by aeration '' refers to the interval in which the measured value does not change significantly when aeration is performed from the aeration means, taking into account the measurement error of the instruments used (Fig. This is because control with the required accuracy is impossible even if measurement is performed in such a section in 83) in 1A.

  Further, in the present invention, “the section in which the aeration means due to the denitrification confirmation means is controlled refers to the section in which the aeration means to be controlled by the denitrification confirmation means is disposed (84 in FIG. 1A). The “section in which the control of the aeration means caused by the nitrification confirmation means is performed” refers to a section (85 in FIG. 1A) where the aeration means to be controlled by the nitrification confirmation means is arranged.

  According to the nitrogen-containing water treatment apparatus of the present invention, in the above invention, the air diffuser includes a region where the nitrification reaction is performed and a region where the denitrification reaction is performed according to the passage of time or the flow direction of the nitrogen-containing water. Alternatively, the gas can be supplied so as to be sequentially, alternately, or repeatedly formed.

  The nitrogen-containing water treatment apparatus according to the present invention, in the above invention, when the gas supply amount control means cannot confirm the denitrification of a desired ratio with respect to the nitric acid generated by nitrification by the nitrification reaction, by the denitrification confirmation means, It is also possible to control increase / decrease of the gas supply amount by the aeration means at least upstream from the denitrification confirmation means along the flow direction of the nitrogen-containing water.

  The apparatus for treating nitrogen-containing water according to the present invention is the above-described invention, wherein the denitrification confirmation unit is a nitric acid concentration measurement unit configured to be capable of measuring a nitric acid concentration, and whether or not a desired ratio of nitric acid is denitrified. This is confirmed by measuring the nitric acid concentration, and the gas supply control means is at least along the flow direction of the nitrogen-containing water so that the nitric acid concentration measured by the nitric acid concentration measuring means is within a predetermined range. It is also possible to control the amount of gas supplied from the aeration means upstream of the nitric acid concentration measurement means.

  The treatment apparatus for nitrogen-containing water according to the present invention is the above-described invention, wherein the denitrification confirmation means is ammonia nitrogen measurement means configured to be capable of measuring ammonia nitrogen, and the desired ratio of ammonia nitrogen is denitrification. Confirmation is made by measuring the ammonia nitrogen concentration, and the gas supply control means is at least so that the ammonia nitrogen concentration measured by the ammonia nitrogen measurement means falls within a predetermined range. It is also possible to control the amount of gas supplied from the aeration means upstream of the ammonia nitrogen measurement means along the flow direction of the nitrogen-containing water.

  The nitrogen-containing water treatment apparatus according to the present invention is the above-described invention, wherein the nitrification confirmation means is ammonia concentration measurement means configured to be capable of measuring ammonia concentration, and whether or not a desired ratio of ammonia is nitrified. Confirmation is performed by measuring the ammonia concentration, and the gas supply amount control means has at least a part of the dispersion upstream of the nitrification confirmation means so that the ammonia concentration measured by the ammonia concentration measurement means is within a predetermined range. The amount of gas supplied from the gas means can also be controlled.

  In the nitrogen-containing water treatment apparatus according to the present invention, in the above invention, the ammonia concentration measuring means can be installed in the vicinity of the outflow side of the nitrogen-containing water in the reaction tank.

  In the nitrogen-containing water treatment apparatus according to the present invention, in the above-described invention, the gas supply amount control means is configured such that the gas supply amount from the aeration means to the nitrogen-containing water is such that both the nitric acid concentration and the ammonia concentration are within a predetermined range. The supply amount can be controlled.

  In the nitrogen-containing water treatment apparatus according to the present invention, in the above invention, the gas supply amount control unit is configured to change the gas supply unit and the gas supply amount from the gas diffusion unit over the entire area along the flow direction of the nitrogen-containing water. Can be controlled to be substantially uniform.

  In the nitrogen-containing water treatment apparatus according to the present invention, an anaerobic tank may be provided upstream of the reaction tank in the above invention.

Moreover, the processing method of the nitrogen-containing water of this invention is as follows.
(2) a flow rate control step for controlling the flow rate of nitrogen-containing water flowing into a plurality of reaction vessels of the same type connected in parallel to be the same;
A biological treatment step for performing biological treatment by nitrification reaction and denitrification reaction on nitrogen-containing water flowing in each reaction tank;
Ammonia contained in the nitrogen-containing water is nitrified into nitric acid according to the flow of the nitrogen-containing water in each reaction tank, and each desired proportion of nitric acid is denitrified at each position along the flow direction of the nitrogen-containing water. An air diffusion step for supplying a gas over substantially the entire region in the flow direction to the nitrogen-containing water;
An upstream denitrification section for obtaining a minimum amount of denitrification nitrogen along the flow direction of the nitrogen-containing water in any one of the plurality of reaction tanks, and the upstream denitrification section The desired ratio of nitric acid is denitrified at the first predetermined position in the first predetermined position, which is between the downstream nitrification section for obtaining the finally required nitrified water quality connected to the downstream side of A denitrification confirmation step for confirming the denitrification state of whether or not
A nitrification confirmation step for confirming a nitrification state of whether or not a desired ratio of ammonia is nitrified at a second predetermined position on the downstream side in the downstream nitrification section of the reaction tank in which the denitrification state is confirmed;
Based on the denitrification state confirmed in the denitrification confirmation step, the first along the flow direction of the nitrogen-containing water so that a desired ratio of the nitric acid is denitrified at the first predetermined position. And controlling the gas supply amount in the section where the control of the diffuser means caused by the denitrification confirmation means, including at least the upstream side of the predetermined position, and based on the nitrification state confirmed in the nitrification confirmation step , Following the section in which the control of the aeration means due to the denitrification confirmation means is performed along the flow direction of the nitrogen-containing water so that the desired proportion of ammonia is nitrified at the second predetermined position Gas produced by the air diffuser in a section where the air diffuser is controlled due to the nitrification confirmation device, including at least the upstream side of the second predetermined position. A first gas supply amount control step of controlling the supply amount,
The first predetermined in each reaction tank in a section where the control of the aeration means due to the denitrification confirmation means excluding the section until the aeration effect is manifested by the aeration in the aeration step. A third predetermined position corresponding to the first predetermined position that is the same position as or different from the position, and the second predetermined position in a section in which the control of the aeration means caused by the nitrification confirmation means is performed A dissolved oxygen measurement step of measuring the amount of dissolved oxygen at a fourth predetermined position which is the same position or a different position and corresponds to the second predetermined position;
Reaction in which the denitrification state and the nitrification state are confirmed based on the measured values of the dissolved oxygen concentration measured at the third predetermined position and the fourth predetermined position in the reaction tank in which the denitrification state and the nitrification state are confirmed. A dissolved oxygen target concentration setting step for setting a dissolved oxygen target concentration at each of the third predetermined position and the fourth predetermined position of the reaction tank other than the tank;
In the denitrification confirmation unit of the reaction tank, the measured value of dissolved oxygen in the third predetermined position of the reaction tank other than the reaction tank in which the denitrification state and the nitrification state are confirmed matches the target concentration. The fourth predetermined amount of the reaction tank other than the reaction tank in which the denitrification state and the nitrification state are confirmed is controlled while controlling the gas supply amount by the air diffusion means in the section in which the control of the resulting air diffusion means is performed. A gas for controlling the amount of gas supplied by the air diffuser in the section where the air diffuser is controlled by the nitrification confirmation device of the reaction tank so that the measured value of dissolved oxygen at the position matches the target concentration A second gas supply control step for supply control;
It is characterized by including.

  Further, in the method for treating nitrogen-containing water according to the present invention, in the above-described invention, the region where the nitrification reaction is performed and the region where the denitrification reaction is performed are sequentially performed according to the passage of time or the flow direction of the nitrogen-containing water. It is also possible to supply gas to the nitrogen-containing water so that it is alternately or repeatedly formed.

  In the method for treating nitrogen-containing water according to the present invention, in the above invention, the ratio of nitric acid confirmed in the denitrification confirmation step is the nitric acid concentration at the first predetermined position, and in the gas supply amount control step, denitrification confirmation is performed. It is also possible to control the gas supply amount at least upstream from the first predetermined position along the flow direction of the nitrogen-containing water in the direction in which the nitric acid concentration measured in the step falls within the predetermined range.

  In the method for treating nitrogen-containing water according to the present invention, in the above invention, the proportion of ammonia confirmed in the nitrification confirmation step is the ammonia concentration at the second predetermined position, and in the gas supply control step, in the nitrification confirmation step It is also possible to control the gas supply amount at least upstream from the second predetermined position along the flow direction of the nitrogen-containing water so that the measured ammonia concentration falls within the predetermined range.

  In the method for treating nitrogen-containing water according to the present invention, in the above-described invention, in the nitrification confirmation step, the second predetermined position may be near the outflow part of the nitrogen-containing water in the reaction tank.

The control device according to the present invention is as follows.
(3) In any one reaction tank among a plurality of reaction tanks of the same type connected in parallel and controlled to have the same flow rate of inflowing nitrogen-containing water, in the flow direction of the nitrogen-containing water And an upstream denitrification section for obtaining a minimum necessary denitrification amount, and a downstream nitrification section for obtaining a finally required nitrification water quality connected to the downstream side of the upstream denitrification section, A denitrification confirmation means for confirming a denitrification state of whether or not a desired ratio of nitric acid is denitrified, provided at a first predetermined position, and on the downstream side in the downstream nitrification section There is provided a nitrification confirmation means for confirming a nitrification state provided at a second predetermined position for confirming whether or not a desired ratio of ammonia is nitrified at the second predetermined position. Contains nitrogen-containing water according to the flow of The ammonia is nitrified into nitric acid, and the nitrogen-containing water is degassed over substantially the entire area in the flow direction so that each desired proportion of nitric acid is denitrified at each position along the flow direction of the nitrogen-containing water. And the first predetermined position in a section where the control of the aeration means caused by the denitrification confirmation means excluding the section until the aeration effect by the aeration means is expressed, Whether the position is the same as or different from the third predetermined position corresponding to the first predetermined position and the same position as the second predetermined position in the section in which the control of the air diffuser due to the nitrification confirmation means is performed. Or a different position that is provided at a fourth predetermined position corresponding to the second predetermined position and that measures the dissolved oxygen amount of the nitrogen-containing water at the third predetermined position and the fourth predetermined position, respectively. Oxygen content In the case of having a constant section, a control apparatus of the air diffuser means to be used for the air diffuser unit,
Based on the denitrification state confirmed by the denitrification confirmation means, the denitrification along the flow direction of the nitrogen-containing water so that a desired ratio of the nitric acid is denitrified at the first predetermined position. The amount of gas supplied by the air diffuser is controlled in the section where the air diffuser is controlled by the denitrifier confirmer including at least the upstream side of the nitrogen confirmer, and confirmed by the nitrification confirmer. Control of aeration means due to the denitrification confirmation means along the flow direction of the nitrogen-containing water so that a desired ratio of the ammonia is nitrified at the second predetermined position based on the nitrification state In the section in which the control of the aeration means caused by the nitrification confirmation means is performed, which is the section following the section where the nitrification confirmation means is included. A first gas supply amount control means for controlling the supply amount of that gas,
Based on the respective dissolved oxygen amounts measured at the third predetermined position and the fourth predetermined position of the reaction tank provided with the denitrification confirmation means and the nitrification confirmation means, the denitrification confirmation means and the nitrification confirmation Means for setting a dissolved oxygen target concentration at each of the third predetermined position and the fourth predetermined position in a reaction tank other than the reaction tank provided with the means;
The denitrification of the reaction tank so that the measured value of dissolved oxygen in the third predetermined position of the reaction tank other than the reaction tank provided with the denitrification confirmation means and the nitrification confirmation means matches the target concentration. A reaction tank other than the reaction tank provided with the denitrification confirmation means and the nitrification confirmation means, as well as controlling the gas supply amount by the aeration means in the section in which the control of the aeration means due to the confirmation means is performed The measured value of the dissolved oxygen at the fourth predetermined position of the reaction tank is controlled so that the gas diffused by the air diffuser is controlled in the section where the air diffuser is controlled by the nitrification confirmation device of the reaction tank. A second gas supply amount control means for controlling the supply amount;
It is characterized by providing.

The control method according to the present invention is as follows.
(4) In any one reaction tank among a plurality of reaction tanks of the same type that are connected in parallel and controlled to have the same flow rate of the nitrogen-containing water flowing in, in the flow direction of the nitrogen-containing water. And an upstream denitrification section for obtaining a minimum necessary denitrification amount, and a downstream nitrification section for obtaining a finally required nitrification water quality connected to the downstream side of the upstream denitrification section, A denitrification confirmation means for confirming a denitrification state of whether or not a desired ratio of nitric acid is denitrified, provided at a first predetermined position, and on the downstream side in the downstream nitrification section There is provided a nitrification confirmation means for confirming a nitrification state provided at a second predetermined position for confirming whether or not a desired ratio of ammonia is nitrified at the second predetermined position. Contains nitrogen-containing water according to the flow of The ammonia is nitrified into nitric acid, and the nitrogen-containing water is degassed over substantially the entire area in the flow direction so that each desired proportion of nitric acid is denitrified at each position along the flow direction of the nitrogen-containing water. And the first predetermined position in a section where the control of the aeration means caused by the denitrification confirmation means excluding the section until the aeration effect by the aeration means is expressed, Whether the position is the same as or different from the third predetermined position corresponding to the first predetermined position and the same position as the second predetermined position in the section in which the control of the air diffuser due to the nitrification confirmation means is performed. Or a different position that is provided at a fourth predetermined position corresponding to the second predetermined position and that measures the dissolved oxygen amount of the nitrogen-containing water at the third predetermined position and the fourth predetermined position, respectively. Oxygen content In the case of having a constant section, a control method of the air diffuser means to be used for the air diffuser unit,
Based on the denitrification state confirmed by the denitrification confirmation means, the denitrification along the flow direction of the nitrogen-containing water so that a desired ratio of the nitric acid is denitrified at the first predetermined position. The amount of gas supplied by the air diffuser is controlled in the section where the air diffuser is controlled by the denitrifier confirmer including at least the upstream side of the nitrogen confirmer, and confirmed by the nitrification confirmer. Control of aeration means due to the denitrification confirmation means along the flow direction of the nitrogen-containing water so that a desired ratio of the ammonia is nitrified at the second predetermined position based on the nitrification state In the section in which the control of the aeration means caused by the nitrification confirmation means is performed, which is the section following the section where the nitrification confirmation means is included. A first gas supply amount control step of controlling the supply amount of the gas that,
Based on the respective dissolved oxygen amounts measured at the third predetermined position and the fourth predetermined position of the reaction tank provided with the denitrification confirmation means and the nitrification confirmation means, the denitrification confirmation means and the nitrification confirmation Setting a dissolved oxygen target concentration at each of the third predetermined position and the fourth predetermined position in a reaction tank other than the reaction tank provided with the means;
The denitrification of the reaction tank so that the measured value of dissolved oxygen in the third predetermined position of the reaction tank other than the reaction tank provided with the denitrification confirmation means and the nitrification confirmation means matches the target concentration. A reaction tank other than the reaction tank provided with the denitrification confirmation means and the nitrification confirmation means, as well as controlling the gas supply amount by the aeration means in the section in which the control of the aeration means due to the confirmation means is performed The measured value of the dissolved oxygen at the fourth predetermined position of the reaction tank is controlled so that the gas diffused by the air diffuser is controlled in the section where the air diffuser is controlled by the nitrification confirmation device of the reaction tank. A second gas supply amount control step for controlling the supply amount;
It is characterized by including.

Furthermore, the program according to the present invention is as follows.
(5) a flow rate control step for controlling the flow rate of nitrogen-containing water flowing into each of a plurality of reaction tanks of the same type connected in parallel to be the same;
An upstream denitrification section for obtaining a minimum amount of denitrification nitrogen along the flow direction of the nitrogen-containing water in any one of the plurality of reaction tanks, and the upstream denitrification section The desired ratio of nitric acid is denitrified at the first predetermined position in the first predetermined position, which is between the downstream nitrification section for obtaining the finally required nitrified water quality connected to the downstream side of A denitrification confirmation step for confirming the denitrification state of whether or not
A nitrification confirmation step for confirming a nitrification state of whether or not a desired ratio of ammonia is nitrified at a second predetermined position on the downstream side in the downstream nitrification section of the reaction tank in which the denitrification state is confirmed;
Based on the denitrification state confirmed in the denitrification confirmation step, the first along the flow direction of the nitrogen-containing water so that a desired ratio of the nitric acid is denitrified at the first predetermined position. The amount of gas supplied from the air diffuser in the section where the air diffuser is controlled due to the denitrification confirming unit including at least the upstream side of the predetermined position is controlled and confirmed in the nitrification confirming step. Based on the nitrification state, the control of the aeration means caused by the denitrification confirmation means along the flow direction of the nitrogen-containing water is performed so that the desired ratio of the ammonia is nitrified at the second predetermined position. The aeration in the section that follows the section to be performed and in which the control of the aeration means due to the nitrification confirmation means including at least the upstream side from the second predetermined position is performed. A first gas supply amount control step of controlling the supply amount of the gas from stage,
The first predetermined in each reaction tank in a section where the control of the aeration means due to the denitrification confirmation means excluding the section until the aeration effect is manifested by the aeration in the aeration step. A third predetermined position corresponding to the first predetermined position that is the same position as or different from the position, and the second predetermined position in a section in which the control of the aeration means caused by the nitrification confirmation means is performed A dissolved oxygen measurement step of measuring the amount of dissolved oxygen at a fourth predetermined position which is the same position or a different position and corresponds to the second predetermined position;
Reaction in which the denitrification state and the nitrification state are confirmed based on the measured values of the dissolved oxygen concentration measured at the third predetermined position and the fourth predetermined position in the reaction tank in which the denitrification state and the nitrification state are confirmed. A dissolved oxygen target concentration setting step for setting a dissolved oxygen target concentration at each of the third predetermined position and the fourth predetermined position of the reaction tank other than the tank;
In the denitrification confirmation unit of the reaction tank, the measured value of dissolved oxygen in the third predetermined position of the reaction tank other than the reaction tank in which the denitrification state and the nitrification state are confirmed matches the target concentration. The fourth predetermined amount of the reaction tank other than the reaction tank in which the denitrification state and the nitrification state are confirmed is controlled while controlling the gas supply amount by the air diffusion means in the section in which the control of the resulting air diffusion means is performed. The amount of gas supplied by the air diffuser is controlled in a section where the air diffuser is controlled by the nitrification confirmation unit of the reaction tank so that the measured value of dissolved oxygen at the position matches the target concentration. A second gas supply control step for controlling gas supply;
It is characterized by including.

  According to the treatment apparatus and treatment method for nitrogen-containing water of the present invention, in a treatment facility for nitrogen-containing water in which a plurality of reaction tanks of the same type are connected in parallel, desorption using an ammonia detector or a nitric acid detector is performed. Other than the reactor equipped with the denitrification confirmation means and the nitrification confirmation means based on the dissolved oxygen amount distribution in the reaction tank in which the aeration means is controlled so that the appropriate denitrification and nitrification is performed by the nitrogen confirmation means and the nitrification confirmation means Since the amount of dissolved oxygen in other reaction tanks is controlled, the aeration means can be controlled in the other reaction tanks with the same degree of accuracy as the reaction tank in which the aeration means is controlled by the denitrification confirmation means and the nitrification confirmation means. In addition, an inexpensive DO meter can be used as a detector.

FIG. 1A is a block diagram showing a processing apparatus in which a plurality of reaction vessels of the present invention are connected in parallel. FIG. 1B is a schematic view of a nitrogen-containing water treatment apparatus including any one reaction tank 2A of the plurality of reaction tanks of the present invention. FIG. 2A is a plan view showing a reaction tank 2A in the nitrogen-containing water treatment apparatus according to the first embodiment of the present invention. FIG. 2B is a plan view showing another modification of the reaction tank 2A in the nitrogen-containing water treatment apparatus according to the first embodiment of the present invention. FIG. 3 is a graph showing the nitrogen concentration and total nitrogen concentration of NH ₄ —N, NO ₂ —N, and NO ₃ —N measured along the flow of water to be treated in the reaction tank. FIG. 4 is a flowchart showing a method for treating nitrogen-containing water according to the first embodiment of the present invention. FIG. 5 is a configuration diagram showing a nitrogen-containing water treatment apparatus according to the second embodiment of the present invention. FIG. 6 is a perspective perspective view showing a reaction tank according to the third embodiment of the present invention. FIG. 7A is a cross-sectional view taken along line AA in the reaction tank shown in FIG. FIG. 7B is a cross-sectional view taken along line BB in the reaction tank shown in FIG. FIG. 8A is a configuration diagram showing another modification of the reaction vessel according to the embodiment of the present invention. FIG. 8B is a configuration diagram showing another modification of the reaction vessel according to the embodiment of the present invention. FIG. 8C is a configuration diagram showing another modification of the reaction vessel according to the embodiment of the present invention. FIG. 8D is a timing chart showing the timing of aeration with the lapse of time of the air diffuser in the reaction tank shown in FIG. 8C. FIG. 8E is a configuration diagram showing another modification of the reaction vessel according to the embodiment of the present invention. FIG. 8F is a schematic cross-sectional view of a carrier carrying microorganisms suspended in the reaction tank shown in FIG. 8E. FIG. 9A is a configuration diagram showing a case where an ammonia meter is installed in the nitrogen-containing water treatment apparatus shown in FIG. 5. FIG. 9B shows each nitrogen of NH ₄ —N, NO ₂ —N, and NO ₃ —N measured along the flow of water to be treated in the reaction tank for explaining the target nitrification rate and the measured nitrification rate. It is a graph which shows a density | concentration and a total nitrogen concentration.

  Embodiments of the present invention will be described below with reference to the drawings. In all the drawings of the following embodiments, the same or corresponding parts are denoted by the same reference numerals. Further, the present invention is not limited to the embodiments described below.

  First, the configuration of the nitrogen-containing water treatment apparatus including the control apparatus according to the first embodiment of the present invention will be described. FIG. 1A is a schematic diagram illustrating an outline of a nitrogen-containing water treatment apparatus. As shown in FIG. 1A, the nitrogen-containing water treatment apparatus of the present invention includes a plurality of treatment apparatuses including nitrogen-containing water reaction tanks (2A, 2B,...) Of the same type connected in parallel. The treatment apparatus is supplied with nitrogen-containing water at the same flow rate by the flow rate adjusting means 61. The flow rate adjusting means 61 includes a flow meter, a flow rate adjusting valve, and the like. In the present invention, the reaction tank of the same type refers to a reaction tank having the same treatment configuration of nitrogen-containing water including aeration means.

(First embodiment)
(Configuration of nitrogen-containing water treatment device: any one of a plurality of reaction vessels)
FIG. 1B is a schematic diagram showing the configuration of any one reaction tank 2A among the plurality of reaction tanks of the present invention. As shown in FIG. 1B, the nitrogen-containing water treatment apparatus according to the first embodiment including any one reaction tank 2A among the plurality of reaction tanks of the present invention includes a first sedimentation tank 1 and a plurality of stages that are sequentially communicated. The reaction tank 2 which consists of aerobic tank 2a, 2b, 2c, 2d (1st tank-4th tank), the solid-liquid separation tank 3, the sludge return path 5, and the control part 9 are provided. The first sedimentation tank 1 and the solid-liquid separation tank 3 are common to the reaction tanks (2A, 2B,...), And the nitrogen-containing water treated in the first sedimentation tank 1 is distributed to each reaction tank. Alternatively, the treated water from each reaction tank (2A, 2B,...) Can be collected and solid-liquid separated.

  Nitrogen-containing raw water (hereinafter, raw water) flows into the first sedimentation basin 1. In the first settling basin 1, raw water is allowed to flow gently to deposit dust with relatively small particles.

  To-be-treated water that is nitrogen-containing water that has flowed out of the sedimentation tank 1 first flows into the reaction tank 2A. A plurality of aerobic tanks 2a to 2d constituting the reaction tank 2A are arranged along the flow direction of the water to be treated. Here, a BOD oxidation region may occur on the inflow side of the water to be treated in the reaction tank 2A. And the aerobic tank 2a-2d is equipped with the aeration part 6a, 6b, 6c, 6d as an aeration means, respectively. The air diffusers 6a to 6d diffuse gas into the aerobic tanks 2a to 2d using a gas such as air supplied by the blower 8, and aerate the stored activated sludge. In each of the aerobic tanks 2a to 2d, ammonia nitrogen contained in the water to be treated is mainly nitrified into nitrite nitrogen and nitrate nitrogen under aerobic conditions. The aerobic tanks 2a to 2d provided with the respective air diffusers 6a to 6d may be arranged in a straight line, and as shown in FIG. 2A, which is a plan view showing an example of the reaction tank 2A, it is folded halfway. It is good also as a detour channel arranged in order.

  Moreover, as shown to FIG. 1B, gas supply amount control part 10a, 10b, 10c, 10d as a part of gas supply amount control means which comprises a control apparatus is each provided in the aeration part 6a-6d. Yes. Each of the gas supply amount control units 10a to 10d is composed of a gas flow rate control valve or the like, and each aerobic tank 2a according to a control signal from the control unit 9 as a part of the gas supply amount control means constituting the control device. The gas supply amount from the air diffusers 6a to 6d at ˜2d is controlled uniformly or individually. As the gas, an oxygen-containing gas such as air is used.

  The control unit 9 as a control device includes, for example, a computer (PC) configured to include a CPU, a storage medium such as a ROM and a RAM, and a recording medium such as a hard disk. In the control unit 9, a predetermined program capable of executing a nitrogen-containing water treatment method and a control method described later is stored in the recording medium. As will be described later, the control unit 9 outputs a control signal according to a stored program in response to a confirmation signal such as input measurement value data of nitric acid concentration or oxygen concentration, whereby each reaction tank (2A, 2A, 2B, 2C...)) Is controlled to control gas supply amounts from the air diffusers 6a to 6d.

  A nitric acid meter 7 is provided at a desired position along the flow of the water to be treated in the reaction tank 2A. The nitric acid meter 7 as the nitrogen confirmation means is a nitric acid concentration measuring means for measuring the nitric acid concentration of the water to be treated at a desired position for controlling the denitrification. In this 1st Embodiment, the nitric acid meter 7 is installed in the inflow position of the aerobic tank 2c which is the substantially middle position of the reaction tank 2, for example. Here, the installation position of the nitric acid meter 7 can be set to a desired position, and is used for controlling the denitrification reaction as will be described later. Therefore, the downstream side of the position where the amount of nitrogen desired to be removed by the denitrification reaction can be secured. And it is desirable that it is upstream from the position where the nitrification reaction can be sufficiently performed in the reaction tank 2. Furthermore, the installation position of the nitric acid meter 7 is determined based on the position dependency of the reaction tank 2 with respect to the total nitrogen concentration, nitrate nitrogen, nitrite nitrogen, and ammonia nitrogen measured in advance. That is, an upstream denitrification section 81 for obtaining a minimum necessary denitrification amount, and a downstream nitrification section 82 for obtaining a finally required nitrification water quality connected to the downstream side of the upstream denitrification section. (First predetermined position). The control unit 9, the gas supply amount control unit 10, and the nitric acid meter 7 constitute a nitrogen-containing water treatment system.

In this specification, nitric acid means nitric acid (HNO ₃ ), nitrous acid (HNO ₂ ), nitrate nitrogen (NO ₃ —N), nitrite nitrogen (NO ₂ —N), nitrate nitrogen and nitrous acid. It is a concept that includes NOx that represents both the aggregation with nitrogen and both nitric acid and nitrous acid. Further, in this specification, ammonia is a concept including ammonia and ammoniacal nitrogen. That is, in this specification, the nitric acid concentration is any one of nitric acid, nitrous acid, nitrate nitrogen, nitrite nitrogen, aggregation of nitrate nitrogen and nitrite nitrogen, and NOx indicating both nitric acid and nitrite. The ammonia concentration may be any of ammonia (NH ₃ ) and ammoniacal nitrogen (NH ₄ —N).

  Further, even when the plurality of aerobic tanks 2a to 2d constituting the reaction tank 2A are arranged in a folded manner as shown in FIG. 2A, the nitric acid meter 7 follows the flow of water to be treated in the reaction tank 2A. It is provided at the first predetermined position, for example, the inflow position of the aerobic tank 2c. In addition, the detail regarding the installation position (1st predetermined position) of the nitric acid meter 7 is mentioned later.

  As shown in FIG. 1B, an ammonia meter 11 as an ammonia concentration measuring means capable of measuring ammonia concentration is provided downstream of the nitric acid meter 7 in the reaction tank 2A as a nitrification confirmation means for confirming the nitrification reaction. Is provided. The ammonia meter 11 can be provided at an arbitrary position (second predetermined position) as long as it is downstream of the nitric acid meter 7. In the first embodiment, since it is important to measure the ammonia concentration of the treated water supplied to the solid-liquid separation tank 3 in the subsequent stage, the aerobic tank on the outflow side (outlet side) of the reaction tank 2 It is preferable to provide in the vicinity of the 2d outflow side.

  As shown in FIG. 1B, the nitric acid meter 7 supplies the measured nitric acid concentration value to the control unit 9, and the ammonia meter 11 supplies the measured ammonia concentration value to the control unit 9. The controller 9 to which the nitric acid concentration value measured by the nitric acid meter 7 and the ammonia concentration value measured by the ammonia meter 11 are supplied controls the gas supply amount based on these nitric acid concentration and ammonia concentration values. A control signal is supplied to the units 10a to 10d to control the gas supply amount by the air diffusers 6a to 6d. That is, the gas supply amount control means is configured by the control unit 9 and the gas supply amount control units 10a to 10d. Details of the control by the control unit 9 will be described later.

  To-be-treated water that has flowed out of the most downstream aerobic tank 2d flows into the solid-liquid separation tank 3. In the solid-liquid separation tank 3, the water to be treated is separated into the separation liquid 4a and the activated sludge 4b. A pipe (not shown) is connected to the side wall of the solid-liquid separation tank 3, and the separation liquid 4a is sent to the disinfection process through this pipe. The sludge return path 5 is connected to the bottom of the solid-liquid separation tank 3 so that the activated sludge 4b deposited on the bottom of the solid-liquid separation tank 3 can be returned to the aerobic tank 2a. Thereby, the biomass in the aerobic tank 2a and the downstream aerobic tanks 2b, 2c, and 2d can be maintained at a predetermined amount.

(Gas supply control in nitrogen treatment method)
Next, a nitrogen-containing water treatment method performed in the aerobic tanks 2a to 2d, a control method associated therewith, and a gas supply amount control by a program executed by the control unit 9 will be described. FIG. 4 is a flowchart showing the processing method according to the first embodiment.

In the treatment method of nitrogen-containing water performed in these aerobic tanks 2a to 2d, first, the water to be treated from the first sedimentation tank 1 shown in FIG. 1B is transferred from the aerobic tank 2a of the reaction tank 2A to the aerobic tank 2d. Sent sequentially. In each of the aerobic tanks 2a to 2d, ammonia nitrogen (NH ₄ -N) in the water to be treated is converted into the following reaction formula (1) by nitrifying bacteria that are aerobic microorganisms in activated sludge under aerobic conditions. ) To (3), and nitrified to nitrite nitrogen (NO ₂ —N) or nitrate nitrogen (NO ₃ —N) (step ST 1 and step ST 2 in FIG. 4).

NH ₃ + O ₂ + 2e ⁻ + 2H + → NH ₂ OH + H ₂ O (1)
NH ₂ OH + H ₂ O → NO ₂ ⁻ + 5H ++ 4e ⁻ (2)
^{_{NO 2 - + 0.5O 2 → NO}} 3 - ············ (3)

On the other hand, in a region where the amount of oxygen in the water to be treated in the reaction tank 2A is small or in a nitrification tank, a denitrification reaction (anaerobic reaction) due to denitrifying bacteria occurs because the amount of oxygen is small. If a sufficient carbon source is supplied to a region where the denitrification reaction occurs (denitrification reaction region), the denitrification reaction can sufficiently proceed. As a result, a region where a denitrification reaction is performed partially occurs in the reaction tank 2A. As a result, as shown in the following reaction formulas (4) to (10), nitrous oxide (N ₂ O) gas generated due to insufficient nitrification is not decomposed or nitrous oxide is not generated. Nitrous acid can be reduced or decomposed into nitrogen and carbon dioxide to remove nitrogen.

NO ₂ ⁻ + 3H ⁺ + 2e ⁻ → 0.5N ₂ O + 1.5H ₂ O (4)
NO ₂ ⁻ + H ⁺ +2 (H) → 0.5N ₂ O + 1.5H ₂ O (5)
^{_{NO 3 - + H + +5 (}} H) → 0.5N 2 + 3H 2 O ······· (6)
^{_{NO 3 - + 2H → NO 2}} - + H 2 O ·············· (7)
NO ₂ ⁻ + H ⁺ + (H) → NO + H ₂ O (8)
NO + (H) → 0.5N ₂ O + 0.5H ₂ O (9)
N ₂ O + 2 (H) → N ₂ + H ₂ O (10)

Here, in the case where the denitrification reaction and the nitrification reaction proceed in parallel, the present inventor is directed from the inflow side of the aerobic tank 2a to the outflow side of the aerobic tank 2d in the reaction tank 2A, that is, Each of ammonia nitrogen (NH ₄ -N), nitrite nitrogen (NO ₂ -N), and nitrate nitrogen (NO ₃ -N) at a plurality of positions along the direction of the water to be treated And the total nitrogen concentration of these were measured. FIG. 3 is a graph showing the results of measuring the nitrogen concentration and total nitrogen concentration of NH ₄ —N, NO ₂ —N, and NO ₃ —N according to the position of the reaction tank 2A.

As shown in FIG. 3, from the inflow side of the aerobic tank 2a, which is a relatively first half side of the reaction tank 2A, to the position on the outflow side of the aerobic tank 2b, NO ₂ —N and NO The nitrogen concentration of _3- N does not increase so much and the total nitrogen concentration decreases. This is because the nitrification reaction region and the denitrification reaction region exist in the aerobic tanks 2a and 2b upstream of the reaction tank 2A, and the nitrification treatment in the nitrification reaction region and the denitrification treatment in the denitrification reaction region proceed simultaneously. This is because the nitrogen removal rate is improved. Further, the nitrogen concentration of NO ₂ —N and NO ₃ —N increases from the inflow side of the aerobic tank 2 c, which is the latter half of the reaction tank 2 A, to the position on the outflow side of the aerobic tank 2 d.

Furthermore, as shown in FIG. 3, the nitrogen concentration of NH ₄ —N greatly decreases toward the outflow side of the reaction tank 2A on the relatively second half side in the reaction tank 2A. That is, the present inventor considered that the denitrification reaction continued to proceed and the nitrification reaction proceeded rapidly in the aerobic tanks 2c and 2d on the downstream side of the reaction tank 2A. Therefore, the present inventor first installs the nitric acid meter 7 at a desired position where the nitrogen concentration in the reaction tank 2A decreases, and supplies gas at least upstream from the nitric acid meter 7 based on the nitric acid concentration at this position. It was recalled that both the denitrification reaction and the nitrification reaction occurring upstream of the nitric acid meter 7 can be controlled by controlling the amount substantially uniformly or individually.

Specifically, as the water to be treated flows down in the reaction tank 2A, the present inventor gradually added ammonia (NH ₄ ) contained in the water to be treated by the air diffusers 6a to 6d to nitric acid (nitrite nitrogen (NO). ₂₋ N) and nitrate nitrogen (NO ₃ —N)), by supplying gas to the water to be treated in the reaction tank 2A over substantially the entire flow direction, It was found that each desired ratio of nitric acid produced by nitrification at each position in the flow direction of the water to be treated in the reaction tank 2A is denitrified. Thereby, the inventor installs the nitric acid meter 7 at a desired position, and at least from the air diffuser 6 upstream of the nitric acid meter 7 so that the measurement value measured by the nitric acid meter 7 falls within a predetermined range. It has been found that the denitrification reaction and the nitrification reaction on the upstream side of the nitric acid meter 7 can be controlled by uniformly or individually controlling the gas supply amount.

  Furthermore, according to the inventor's knowledge, by installing the ammonia meter 11 in the region where the nitrification reaction proceeds downstream of the nitric acid meter 7, the nitrification reaction in the latter half of the reaction tank 2A can be controlled, The ammonia concentration in the treated water flowing out from the reaction tank 2A can be controlled. Thus, the present inventor can confirm the progress of the nitrification reaction in the treated water in the reaction tank 2A on the downstream side of the nitric acid meter 7 by measuring the ammonia concentration with the ammonia meter 11, and the state of the denitrification reaction. It was also found that it can be confirmed. That is, the present inventor installs the ammonia meter 11 on the downstream side of the nitric acid meter 7, and at least between the nitric acid meter 7 and the ammonia meter 11 so that the ammonia concentration measured by the ammonia meter 11 falls within a predetermined range. It was found that the denitrification reaction and the nitrification reaction on the upstream side of the ammonia meter 11 can be controlled by controlling the amount of gas supplied from the air diffusers 6c and 6d. Thereby, this inventor can not only maintain the denitrification reaction in the aerobic tanks 2a and 2b which are the relatively first half side of the reaction tank 2A by the return sludge from the solid-liquid separation tank 3, but also relatively It has been recalled that the denitrification reaction in the aerobic tanks 2c and 2d, which are the latter half, can be maintained, and nitrogen can be removed stably.

  Therefore, in the present invention, first, the control unit 9 monitors the nitric acid concentration by the nitric acid meter 7 installed on the inflow side of the aerobic tank 2 c and also monitors the ammonia concentration by the ammonia meter 11 downstream of the nitric acid meter 7. To do. Then, along with the measured value of the nitric acid concentration by the nitric acid meter 7, at least the gas supply amount control units 10 a and 10 b upstream from the nitric acid meter 7 are controlled along the flow direction of the water to be treated, and the ammonia by the ammonia meter 11. In accordance with the measured value of the concentration, the gas supply amount control units 10c and 10d on the downstream side of at least the nitric acid meter 7 are controlled along the flow direction of the water to be treated. Thereby, the control part 9 controls the gas supply amount in 2 A of reaction tanks, ie, the gas supply amount of each aerobic tank 2a-2d.

And when the denitrification of the desired ratio with respect to the nitric acid produced | generated by nitrification reaction by the nitric acid meter 7 cannot be confirmed, the diffuser 6a on the upstream side at least upstream from the nitric acid meter 7 along the flow direction of the water to be treated. The amount of gas supplied by 6b is controlled individually or uniformly. And the control part 9 can control denitrification reaction, suppressing nitrification reaction in the to-be-processed water in the upstream of the nitric acid meter 7 in the reaction tank 2A by controlling these gas supply amounts. On the downstream side of the nitric acid meter 7, the amount of dissolved oxygen in the treated water increases along the flow from the upstream side to the downstream side of the treated water, so that the treated water is more favorable while the denitrification reaction proceeds. The nitrification reaction proceeds rapidly under atmospheric conditions, ammonia (NH ₄ ) decreases rapidly, and nitric acid (nitrite nitrogen (NO ₂ -N) and nitrate nitrogen (NO ₃ -N)) Concentration increases rapidly.

In this case, in consideration of controlling the denitrification reaction in the reaction tank 2A, the nitric acid meter 7 is located in a region where the denitrification reaction and the nitrification reaction coexist, for example, the nitrification reaction. It is desirable to install it at the most downstream side of the region in the reaction tank 2A in which the denitrification reaction needs to proceed while suppressing the generation of nitric acid due to. Thereby, in the to-be-processed water upstream from the nitric acid meter 7 in the reaction tank 2A, the denitrification reaction can be advanced while suppressing the nitrification reaction. Moreover, since the amount of dissolved oxygen in the water to be treated increases along the flow from the upstream side to the downstream side of the water to be treated on the downstream side from the nitric acid meter 7, the water to be treated is more advanced while the denitrification reaction proceeds. The nitrification reaction proceeds rapidly under aerobic conditions, and ammonia (NH ₄ ) decreases rapidly. As the nitrification reaction proceeds, the concentration of nitric acid (nitrite nitrogen (NO ₂ —N) and nitrate nitrogen (NO ₃ —N)) increases rapidly. Therefore, it is desirable to install the ammonia meter 11 in the vicinity of a position where the nitrogen concentration of the ammoniacal nitrogen is almost minimized. Therefore, in the first embodiment, it is desirable to install the ammonia meter 11 on the outflow side of the aerobic tank 2d.

In the first embodiment, first, the nitric acid meter 7 measures the total nitric acid concentration of NO ₂ —N and NO ₃ —N on the inflow side of the aerobic tank 2 c (step ST 3 in FIG. 4). In addition, the ammonia meter 11 measures the NH ₄ —N concentration (ammonia concentration) on the outflow side of the aerobic tank 2d (step ST4 in FIG. 4). After these measurements, the nitric acid meter 7 supplies the measured value of the nitric acid concentration to the control unit 9, and the ammonia meter 11 supplies the measured value of the ammonia concentration to the control unit 9. The controller 9 determines whether or not the supplied ammonia concentration and nitric acid concentration values are within a predetermined range (step ST5 in FIG. 4).

  When the measured value of the nitric acid concentration supplied to the control unit 9 is within a predetermined range, that is, a preset target range (set target range), and the measured value of the ammonia concentration is within the predetermined range (step in FIG. 4) (ST5: Yes), the control unit 9 continues monitoring the nitric acid concentration by the nitric acid meter 7 and monitoring the ammonia concentration by the ammonia meter 11 (steps ST3 and ST4 in FIG. 4).

  On the other hand, the control unit 9 determines that the measured value of the nitric acid concentration is less than the set target range, that is, less than the lower limit of the set target range, or the measured value of the ammonia concentration is outside the predetermined range (step ST5: No in FIG. 4). ) And a control signal is supplied to the gas supply amount control units 10a to 10d to perform control to increase or decrease the gas supply amounts from the air diffusion units 6a to 6d in the aerobic tanks 2a to 2d (FIG. 4, step ST6).

  Specifically, the control unit 9 adjusts the aerobic tanks 2a to 2d, particularly aerobic so that the nitric acid concentration value measured by the nitric acid meter 7 falls within a preset target range of, for example, 5.0 mg / L or less. The gas supply amount in the tanks 2a and 2b is controlled. That is, the control unit 9 determines that the value of the nitric acid concentration supplied from the nitric acid meter 7 is less than the lower limit of the set target range (step ST5: No in FIG. 4), at least in the aerobic tanks 2a and 2b. Control is performed to increase at least the amount of gas supplied from the air diffusers 6a, 6b so as to increase the nitric acid concentration (step ST6 in FIG. 4).

  On the other hand, when the control unit 9 determines that the value of the nitric acid concentration supplied from the nitric acid meter 7 has exceeded the upper limit of the set target range (step ST5: No in FIG. 4), at least nitric acid in the aerobic tanks 2a and 2b. Control is performed to reduce the gas supply amount by at least the air diffusers 6a and 6b so as to reduce the concentration (step ST6 in FIG. 4).

  The control unit 9 controls the gas supply amount based on the nitric acid concentration value, and the ammonia concentration value measured by the ammonia meter 11 is, for example, 1.0 to 5.0 mg / L, preferably 1.0 to 5.0 mg / L. The gas supply amount in the aerobic tanks 2a to 2d, particularly the aerobic tanks 2c and 2d between the nitric acid meter 7 and the ammonia meter 11 is controlled so as to be within 2.0 mg / L. The upper limit value of the ammonia concentration is a value for controlling the nitrification reaction. If this value is too large, the nitrification reaction proceeds too much, and nitrogen removal by the denitrification reaction is reduced. On the other hand, when the lower limit value of the ammonia concentration is larger than 0 mg / L, it is confirmed that a denitrification reaction exists on the downstream side of the nitric acid meter 7 in the reaction tank 2A. Therefore, the lower limit of the ammonia concentration is desirably larger than 0 mg / L. Furthermore, when the ammonia concentration range is smaller than 1.0 mg / L, the measurement accuracy of the ammonia meter 11 is lowered, and when it is larger than 5.0 mg / L, the quality of the treated water is deteriorated. Is taken into consideration, it is desirable to control to 1.0 to 5.0 mg / L. In addition, about this setting target range, the optimal setting target range can be set for every reaction tank according to design, such as the shape of the reaction tank 2A, a dimension.

  Specifically, when the control unit 9 determines that the value of the ammonia concentration supplied from the ammonia meter 11 is, for example, less than 1.0 mg / L (step ST5: No in FIG. 4), at least an aerobic tank In order to increase the ammonia concentration in 2c and 2d, control is performed to decrease the gas supply amount by at least the air diffusers 6c and 6d (step ST6 in FIG. 4). On the other hand, when the control unit 9 determines that the value of the ammonia concentration supplied from the ammonia meter 11 is, for example, 5.0 mg / L, and preferably exceeds 2.0 mg / L (in FIG. 4, step ST5: No). Then, control is performed to increase the gas supply amount by at least the air diffusers 6c and 6d so as to reduce the ammonia concentration in at least the aerobic tanks 2c and 2d (step ST6 in FIG. 4). In addition, in the control of the gas supply amount by the control unit 9, aeration may be performed continuously or intermittently including aeration stop control in which the gas supply amount is set to zero.

  That is, in the above-described control of the air diffusers 6a to 6d, the gas supply amount from the air diffusers 6a to 6d is uniformly increased or decreased, or the gas supply amount from the air diffusers 6a and 6b is increased or decreased. It is possible to keep the gas supply amount from the gas parts 6c and 6d constant. In addition, according to the installation position of the nitric acid meter 7, the aeration part 6 which needs to perform increase / decrease control is selected. Specifically, when the nitric acid meter 7 is installed on the downstream side of the aerobic tank 2a or the upstream side of the aerobic tank 2b, the control unit 9 is controlled by the gas supply amount control unit 10a from the aeration unit 6a. The gas supply amount is controlled. On the contrary, when the nitric acid meter 7 is installed on the upstream side of the aerobic tank 2c or the aerobic tank 2d, the control unit 9 is controlled by the gas supply amount control units 10a to 10c at least from the aeration units 6a to 6c. Control each gas supply. In addition, the control unit 9 selects a plurality of groups regardless of whether independent control is performed for each of the gas supply amount control units 10a to 10d or the same control is performed on each of the air diffusion units 6a to 6d. Control may be performed for each of the diffused air diffusers 6a, 6b, 6c, and 6d.

  Thus, the control part 9 supplies a control signal to each gas supply amount control part 10a, 10b, and controls the gas supply amount in each aeration part 6a, 6b, and aerobic tank 2a, 2b It is possible to control the generation of the denitrification reaction in the reaction tank 2A by appropriately coexisting the denitrification reaction and the nitrification reaction. Further, the control unit 9 supplies a control signal to each of the gas supply amount control units 10c and 10d, and appropriately controls the gas supply amount in each of the air diffusion units 6c and 6d, thereby controlling the ammonia concentration. Since the nitrification reaction in the aerobic tanks 2c and 2d can be controlled, the denitrification reaction in the aerobic tanks 2a and 2b can be maintained by the return sludge. Further, since the controller 9 optimally controls the gas supply amount, the gas supply amount by the air diffusers 6a to 6d can be controlled to a necessary and sufficient amount, and the power consumption of the blower 8 can be reduced. Thus, it is possible to reduce power consumption in the treatment of nitrogen-containing water.

  According to the 1st Embodiment of this invention demonstrated above, in the some aerobic tank 2a-2d which comprises 2 A of reaction tanks, the aerobic tank which is a middle position (1st predetermined position) of 2 A of reaction tanks The nitric acid meter 7 is installed on the inflow portion side of 2c, and the ammonia meter 11 is installed on the outflow side (second predetermined position) of the aerobic tank 2d. Based on the measurement of the ammonia concentration, the gas supply amounts in the aerobic tanks 2a to 2d are controlled so that the nitric acid concentration and the ammonia concentration are within the predetermined ranges. Thereby, the denitrification reaction and the nitrification reaction performed mainly in the aerobic tanks 2a and 2b which are the first half of the reaction tank 2A are controlled, and also performed in the aerobic tanks 2c and 2d which are the latter half of the reaction tank 2A. Since the nitrification reaction can be controlled, the nitrogen removal rate can be improved, and an appropriate amount of oxygen can be supplied to the reaction tank 2 in accordance with the organic load and nitrogen load of the water to be treated.

  In addition, as shown in FIG. 1A, there are other reaction tanks 2B, 2C... Having the same shape as the reaction tank 2A, and when there is an inflow of nitrogen-containing water and return of returned sludge under the same conditions, The reaction tank can control the gas supply rate under the same conditions as the reaction tank 2A, and if it supplies an appropriate amount of oxygen, it has the same accuracy as the reaction tank 2A (any one reaction tank in a plurality of reaction tanks). Can control denitrification and nitrification.

  Therefore, in the present invention, DO meters 67 and 71 are provided corresponding to the nitric acid meter and the ammonia meter in any one reaction tank 2A in the plurality of reaction tanks, respectively. Since these DO meters measure changes in the amount of dissolved oxygen resulting from the control of the amount of air diffused from the air diffuser based on the measured values of the nitric acid meter and the ammonia meter, they correspond to the nitric acid meter. The DO meter only needs to be provided at a predetermined position (third predetermined position) in the section 84 where the aeration means is controlled based on the measured value of the nitric acid meter. The DO meter corresponding to the ammonia meter is What is necessary is just to be provided in the predetermined position (4th predetermined position) in the area 85 where control of an aeration means is performed based on the measured value of an ammonia meter. However, the amount of dissolved oxygen hardly changes in the interval until the aeration effect by the aeration means near the inlet of the reaction tank is exhibited. Therefore, these sections 83 in which changes less than the measurement limit of the DO meter to be used do not make sense to provide the DO meter, and are naturally excluded.

DO tanks 67 and 71 corresponding to a nitric acid meter and an ammonia meter are provided in reaction tanks (2B, 2C,...) Other than any one reaction tank 2A in the plurality of reaction tanks.
On the other hand, the dissolved oxygen amount measured in the DO meters 67 and 71 of any one reaction tank 2A in the plurality of reaction tanks is sent to the control unit 9, and in each reaction tank (2B, 2C...). The target values of the DO meters 67 and 71 are set. And in each reaction tank (2B, 2C,...), The aeration means of the reaction tank is controlled so that the dissolved oxygen amount measured by the DO meters 67, 71 of each reaction tank matches the set target. Is done.
That is, when the measured value of the DO meter 67 in the reaction tank 2B does not match the target value, the aeration means in the reaction tank 2B corresponding to the aeration means 6a and 6b controlled by the denitrification confirmation means in the reaction tank 2A. When the amount of aeration is controlled by 6a and 6b and the measured value of the DO meter 71 in the reaction tank 2B does not match the target value, it corresponds to the aeration means 6c and 6d controlled by the nitrification confirmation means in the reaction tank 2A. The amount of air diffused is controlled by the air diffuser 6c, 6d of the reaction tank 2B.

(Modification 1 of the first embodiment)
Moreover, in this 1st Embodiment, although comprised reaction tank 2A, 2B, 2C ... from the aerobic tank 2a-2d which connected 4 tanks in series, this reaction tank 2A, 2B, 2C, ... It is also possible to use a single tank in which the flow of water to be treated is generated. FIG. 2B is a plan view in the case where the reaction tank 2 is configured as a single tank as Modification 1 of the first embodiment. As shown in FIG. 2B, the air diffuser may be constituted by a single air diffuser 6 instead of the plurality of air diffusers 6a to 6d. Also in this case, the nitric acid meter 7 is provided at the first predetermined position on the most downstream side of the region where the denitrification reaction needs to be controlled along the flow direction of the water to be treated. It is provided at a substantially intermediate position along the flow direction of the water to be treated in the tank 2. In addition, even if it is a case where an aeration means is comprised from the single aeration part 6, you may comprise so that a gas supply amount can be controlled for every gas supply part in the reaction tank 2 in the aeration part 6. FIG. . Even when the reaction tank 2 is a single tank, the air diffuser may be composed of a plurality of air diffusers as in the first embodiment described above. And also when making the reaction tank 2 into a single tank and comprising an aeration means from several aeration parts, you may control a some aeration part mutually independently, or you may control mutually the same. .

(Second Embodiment)
Next, a treatment apparatus for nitrogen-containing water provided with a control device according to the second embodiment of the present invention will be described. FIG. 5 is a block diagram showing a nitrogen-containing water treatment apparatus according to the second embodiment.

  As shown in FIG. 5, in the treatment apparatus for nitrogen-containing water according to the second embodiment, unlike the first embodiment, each aerobic tank 2a, 2b, 2c,. It consists of a nitrification / denitrification reaction tank which is not a tank but a single aerobic tank. The nitric acid meter 7 is installed at a desired position in the flow direction of the water to be treated in the reaction tank 2A, that is, at a predetermined position for controlling the denitrification reaction in the water to be treated further upstream. The nitric acid meter 7 measures the nitric acid concentration at the predetermined position and supplies the measurement result to the control unit 9. Based on the supplied nitric acid concentration, the control unit 9 controls the gas supply amount (aeration amount) of the aeration units 6 a and 6 b at least upstream of the nitric acid meter 7. In addition, the control part 9 can also control the aeration parts 6a-6d uniformly over each reaction tank 2A, 2B, 2C ..., and the aeration parts 6a and 6b and the aeration part. It is also possible to individually control 6c and 6d.

  Moreover, the anaerobic tank 12 is provided in the front | former stage along the flow direction of to-be-processed water with respect to each reaction tank 2A, 2B, 2C .... The anaerobic tank 12 is a tank into which treated water, which is nitrogen-containing water, first flows through the settling tank 1. In the anaerobic tank 12, a stirring unit 12b that can be rotated by an external motor 12a is provided, and the activated sludge in the anaerobic tank 12 is stirred by the stirring unit 12b. Depending on the configuration of the sewage treatment plant, the initial sedimentation site 1 may not be provided. In this case, the raw water first flows into the anaerobic tank 12. The anaerobic tank 12 is a tank for performing dephosphorization treatment (anaerobic treatment) on the water to be treated by the action of phosphorus-accumulating bacteria in an anaerobic environment. And in the anaerobic tank 12, while the organic substance contained in to-be-processed water under anaerobic conditions is taken in into activated sludge, the phosphorus contained in activated sludge is discharge | released into raw | natural water.

  In addition, the activated sludge 4 b deposited on the bottom of the solid-liquid separation tank 3 is returned to the anaerobic tank 12 by the sludge return path 5 connected to the bottom of the solid-liquid separation tank 3. Thereby, the biomass in the anaerobic tank 12 and the downstream reaction tank 2 can be maintained at a predetermined amount. In addition, the remainder of the activated sludge 4b produced | generated in the solid-liquid separation tank 3 is discharged | emitted outside as excess sludge. Since other configurations are the same as those in the first embodiment, description thereof is omitted.

In the second embodiment, a nitric acid meter 7 for supplying the measured nitric acid concentration to the control unit 9 is installed at a first predetermined position of a reaction tank 2A consisting of a single tank, and a second predetermined By installing the ammonia meter 11 for supplying the ammonia concentration measured at the position to the control unit 9, the same effect as in the first embodiment can be obtained.

(Third embodiment)
Next, a nitrogen-containing water treatment apparatus provided with a control apparatus according to the third embodiment of the present invention will be described. FIG. 6 is a perspective perspective view showing the anaerobic tank 12 and the reaction tank 2A in the nitrogen-containing water treatment apparatus according to the third embodiment. In FIG. 6, the side wall on the near side of the drawing in the anaerobic tank 12 and the reaction tank 2A is not shown for the following explanation. 7A and 7B are cross-sectional views of the reaction tank taken along lines AA and BB in FIG. 6, respectively.

  As shown in FIG. 6, the reaction tank 2 </ b> A is composed of a single tank, and an anaerobic tank 12 is provided upstream of the reaction tank 2 along the flow direction of the water to be treated. Raw water flows into the anaerobic tank 12 from one side, and the water to be treated that has been anaerobically treated in the anaerobic tank 12 is supplied to the reaction tank 2A from the other side.

  In addition, a plate-like air diffuser 6 is provided in the reaction tank 2A substantially in the middle along the height direction of the reaction tank 2A. The air diffuser 6 is configured so that the gas supply amount can be adjusted by the gas supply amount controller 10 for each predetermined section along the flow direction of the water to be treated, which is the longitudinal direction of the reaction tank 2A.

  A nitric acid meter 7 capable of measuring nitric acid concentration is installed at a first predetermined position along the flow direction of the water to be treated in the reaction tank 2A, that is, the longitudinal direction of the reaction tank 2A. The nitric acid meter 7 supplies the measured nitric acid concentration to the control unit 9. The control unit 9 supplies a control signal to the gas supply amount control unit 10 according to a predetermined program according to the measurement value of the supplied nitric acid concentration. The gas supply amount control unit 10 controls the gas supply amount so as to be uniform over the entire air diffuser 6 according to the supplied control signal, or for each predetermined section of the air diffuser 6. Control the gas supply rate.

  Furthermore, an ammonia meter 11 capable of measuring the ammonia concentration is installed at a second predetermined position along the flow direction of the water to be treated in the reaction tank 2A, that is, the longitudinal direction of the reaction tank 2A. The ammonia meter 11 supplies the measured ammonia concentration to the control unit 9. The control unit 9 supplies a control signal to the gas supply amount control unit 10 according to a predetermined program according to the measured value of the supplied ammonia concentration. The gas supply amount control unit 10 controls the gas supply amount for each predetermined section of the air diffusion unit 6 according to the supplied control signal.

  Moreover, in the reaction tank 2A, the partition plate 13 is provided in the center part along the longitudinal direction of the reaction tank 2A. The partition plate 13 is installed such that its thickness direction is substantially parallel to the bottom surface of the reaction tank 2A. In other words, the partition plate 13 is installed so that its surface is perpendicular to the bottom surface of the reaction tank 2A. And by this partition plate 13, the inside of the reaction tank 2A is in a state of being partially partitioned with the upper and lower portions of the partition plate 13 opened.

  Then, in the reaction tank 2A configured as described above, when aeration is performed by supplying gas to the water to be treated from the aeration unit 6 while flowing the water to be treated, the aerated gas is supplied to the partition plate 13. It rises along and turns to the opposite surface side in the state partitioned off by the partition plate 13. At the same time, since the water to be treated flows along the longitudinal direction of the reaction tank 2, the aerated gas dissolves in the water to be treated while forming a spiral swirl flow as indicated by an arrow C in FIG. I will do it. Similarly, the water to be treated advances along the longitudinal direction of the reaction tank 2 </ b> A while rotating spirally with the longitudinal axis of the reaction tank 2 as the center. The gas supply amount from the air diffuser 6 is set according to conditions such as the inflow amount of water to be treated and the size and shape of the reaction tank 2.

  Then, as shown by an arrow C in FIG. 7A which is a cross-sectional view at a position where the nitric acid meter 7 is provided, the gas aerated from the air diffuser 6 passes through the gap in the upper part of the partition plate 13 together with the water to be treated. And turn to the other side. Further, the water to be treated accompanying the swirling of the gas passes through the gap in the lower part of the partition plate 13 and reaches the lower part of the air diffuser 6. In this case, the upstream aerobic region 31 and the downstream anaerobic region 32 coexist along the direction of the swirling flow (arrow C). The aerobic region 31 has a nitrification reaction promoted by an aerobic nitrifying bacterium, and constitutes a nitrification region. On the other hand, the anaerobic region 32 has a denitrification reaction promoted by an anaerobic denitrifying bacterium. Configure.

  Then, on the upstream side along the longitudinal direction of the reaction tank 2A, oxygen based on the amount of gas supplied from the diffuser 6 upstream from the position shown in FIG. 7A is dissolved in the water to be treated. On the other hand, the position shown in FIG. 7B, which is a cross-sectional view at the position where the ammonia meter 11 is provided, is further downstream along the longitudinal direction of the reaction tank 2A, so that it is compared with the position shown in FIG. 7A. The amount of dissolved oxygen is increasing. Therefore, the anaerobic region 32 shown in FIG. 7B is smaller than the anaerobic region 32 shown in FIG. 7A. That is, since the water to be treated flows from the upstream side toward the downstream side along the longitudinal direction of the reaction tank 2A, the amount of contact with oxygen increases toward the downstream side, so that dissolved oxygen increases and is aerobic. The region 31 is enlarged. Therefore, in the water to be treated inside the reaction tank 2A, the denitrification region tends to decrease as it goes from the upstream side to the downstream side. On the other hand, the nitrification region tends to increase from the upstream side to the downstream side.

From the above, the denitrification reaction is promoted while the nitrification reaction coexists on the upstream side of the reaction tank 2A, and the nitrification reaction is promoted while the denitrification reaction occurs on the downstream side. As a result, as shown in FIG. 3, the denitrification reaction proceeds immediately after the nitrification reaction on the upstream side of the reaction tank 2A. Therefore, nitrate nitrogen (NO ₃ -N) or nitrite nitrogen ( nO ₂ -N) is hardly emerge. And as it progresses to the downstream side of the reaction tank 2, the concentration of nitric acid increases as the nitrification reaction is promoted while the total nitrogen concentration decreases due to the denitrification reaction. Since other configurations are the same as those in the first and second embodiments, the description thereof is omitted.

  According to the third embodiment described above, the swirl flow of the water to be treated is formed by supplying the gas from the air diffuser 6 while providing the partition plate 13 inside the reaction tank 2A. In addition, while allowing the nitrification reaction and the denitrification reaction to coexist in a controlled manner, it is possible to more efficiently suppress the appearance of nitric acid due to the nitrification reaction on the upstream side and to promote the nitrification reaction on the downstream side. By controlling the aeration unit 6 so that the nitric acid concentration falls within the set range while measuring, it is possible to more accurately control the denitrification reaction and the nitrification reaction in the reaction tank 2A.

(Modification of reaction tank and diffuser)
Next, the modification regarding reaction tank 2A, 2B, 2C ... in the embodiment of this invention mentioned above and the inside aeration part 6 is demonstrated.

(Modification 2)
8A to 8F are configuration diagrams showing reaction vessels 2A, 2B, 2C,. As shown in FIG. 8A, in the reaction tank 2A (2B, 2C,...) According to the modified example 2, a plurality of air diffusers 16a and 16b are provided inside the reaction tank 2A as in the second embodiment. , 16c are provided. Each of these air diffusers 16a to 16c is controlled by gas supply amount control units 19a, 19b, and 19c that control the gas supply amount based on a control signal from the control unit 9 (not shown in FIG. 8A). The Moreover, unlike 2nd Embodiment, between each aeration part 16a-16c is provided at predetermined intervals. That is, while the gas is supplied to the entire reaction tank 2A, the region where the gas is supplied and the region where the gas is not supplied are alternately or repeatedly alternately locally along the flow direction of the water to be treated. It is formed. Thereby, in the reaction tanks 2A, 2B, 2C..., Nitrifying bacteria of aerobic bacteria and facultative anaerobic denitrifying bacteria can coexist and their activities can be activated alternately. Like the reaction tank 2A described in the third embodiment, in the reaction tank 2A, a region where a nitrification reaction occurs and a region where a denitrification reaction occur can be formed with good controllability.

(Modification 3)
FIG. 8B is a configuration diagram showing a reaction tank 2A according to Modification 3. As shown in FIG. 8B, in the reaction tank 2A according to the modified example 3, a plurality of air diffusers 26a, 26b, 26c, 26d, and 26e are provided inside the reaction tank 2A as in the case of 26 in the second embodiment. It has been. And each of these air diffusers 26a to 26e is based on a control signal from the controller 9 (not shown in FIG. 8B), and gas supply amount controllers 29a, 29b, 29c, which control the gas supply amount. It is controlled by 29d and 29e. Further, unlike the second embodiment, the control unit 9 selectively sets an aeration unit that performs aeration and an aeration unit that does not perform aeration for the plurality of aeration units 26a to 26e. . In FIG. 8B, control is performed so that the air diffusers 26a, 26c, and 26e perform aeration and the air diffusers 26b and 26d do not perform air diffuse. Of the diffusers 26a to 26e, the diffuser that performs aeration and the diffuser that does not perform aeration are appropriately selected according to the water quality of the water to be treated flowing in the reaction tank 2A. That is, while the gas is supplied to the entire reaction tank 2A, the region where the gas is supplied and the region where the gas is not supplied are alternately or repeatedly alternately locally along the flow direction of the water to be treated. It is formed. Thereby, in the reaction tank 2A, the aerobic nitrifying bacteria and the facultative anaerobic denitrifying bacteria can coexist and can be activated sequentially, alternately or repeatedly, so that the third Similarly to the reaction tank 2A according to the embodiment, in the reaction tank 2A, a region where a nitrification reaction occurs and a region where a denitrification reaction occur can be formed with good controllability.

(Modification 4)
FIG. 8C is a configuration diagram showing a reaction tank 2A according to Modification 4. As shown in FIG. 8C, in the reaction tank 2A according to the modification 4, a single air diffuser 36 is provided inside the reaction tank 2A, as in the modification 1 in the first embodiment. The air diffuser 36 is controlled by a gas supply amount controller 39 that controls the gas supply amount based on a control signal from the controller 9 (not shown in FIG. 8C). Further, unlike the third modification, the aeration unit 36 is controlled by the control unit 9 so as to perform aeration or no aeration sequentially, alternately or repeatedly as time elapses.

  FIG. 8D is an example of a timing chart showing the timing of the presence or absence of aeration. As shown in FIG. 8D, the time during which aeration is performed by the air diffuser 36 (ON in FIG. 8D) and the time during which aeration is not performed (OFF in FIG. 8D) are the water to be treated flowing in the reaction tank 2A. It is appropriately set according to various conditions such as water quality. That is, while the gas is supplied to the entire reaction tank 2A, the time when the gas is supplied to the water to be treated and the time when the gas is not supplied are sequentially or alternately set as time passes. Thereby, in the reaction tank 2A, the aerobic bacteria nitrifying bacteria and the facultative anaerobic denitrifying bacteria can coexist and be activated sequentially, alternately or repeatedly over time. Therefore, similarly to the reaction tank 2A described in the third embodiment, the area where the nitrification reaction occurs and the area where the denitrification reaction occurs can be formed with good controllability in the reaction tank 2A.

(Modification 5)
Further, FIG. 8E is a configuration diagram showing a reaction tank 2A according to Modification 5. As shown in FIG. 8E, in the reaction tank 2 </ b> A according to the modified example 5, a single aeration unit 46 is provided inside the reaction tank 2 </ b> A as in the modified example 4. The air diffuser 46 is controlled by a gas supply amount control unit 49 that controls the gas supply amount based on a control signal from the control unit 9 (not shown in FIG. 8E). A plurality of carriers 43 carrying both aerobic nitrifying bacteria and facultative anaerobic denitrifying bacteria are introduced into the reaction tank 2A. When the gas is supplied from the air diffuser 46 into the reaction tank 2A, the reaction tank 2A is stirred, the carrier 43 flows in the treated water, and the carrier 43 is distributed substantially uniformly in the treated water. FIG. 8F is a sectional view showing a sectional structure of the carrier 43.

  As shown in FIG. 8F, the carrier 43 is made of a granular resin carrier, and the size and shape of the carrier 43 are various sizes and shapes as long as the carrier 43 can retain bacteria even if it flows in the water to be treated. Can be adopted. For example, a cylindrical shape, a spherical shape, or the like having an outer diameter dimension of about several mm is preferable. In addition, aerobic nitrifying bacteria are mainly carried in the nitrification reaction zone on the surface of the carrier 43, and facultative anaerobic denitrifying bacteria are mainly carried in the denitrification reaction zone. Specifically, the carrier 43 contains aerobic nitrifying bacteria contributing to the nitrification reaction in the outer region 43a, and facultative anaerobic denitrifying bacteria contributing to the anaerobic denitrification reaction in a form surrounded by the nitrifying bacteria. As the dominant species, two layers of microbial membranes to be present in the inner region 43b are supported on the surface portion. As a result, in the carrier 43 in the water to be treated, nitrifying bacteria located on the outer side are set as aerobic conditions as dominant species, and denitrifying bacteria located on the inner side have anaerobic conditions surrounded by the nitrifying bacteria. Secured.

  That is, while the gas is supplied to the entire reaction tank 2A, aerobic nitrifying bacteria and anaerobic denitrifying bacteria coexist by the carrier 43 itself in the water to be treated in the reaction tank 2, and the nitrification reaction is performed. A state in which the denitrification reaction coexists can be formed. Thereby, in the reaction tank 2A, nitrification bacteria of aerobic bacteria and facultative anaerobic denitrification bacteria can coexist and their activities can be activated together. And denitrification can coexist with good controllability.

(Modification 6)
Next, Modification 6 will be described. FIG. 9A is a configuration diagram of a nitrogen-containing water treatment apparatus according to Modification 6 corresponding to FIG. 5 in the second embodiment. FIG. 9B shows NH ₄ —N, NO ₂ —N, and NO corresponding to FIG. 3 measured along the flow of water to be treated in the reaction tank 2A for explaining the target nitrification rate and the measured nitrification rate. It is a graph which shows each nitrogen concentration of _3- N, and a total nitrogen concentration. In this modified example 6, a pair of ammonia meters is used as denitrification confirmation means.

  That is, as shown in FIG. 9A, in the modified example 6, unlike the second embodiment, instead of the nitric acid meter 7 in the reaction tank 2A, the first upstream side along the flow direction of the water to be treated is used. A nitrification rate meter 58 comprising a pair of ammonia meters of an ammonia meter 58a and a second ammonia meter 58b on the downstream side is installed. The measured values of the ammonia concentration measured by the first ammonia meter 58a and the second ammonia meter 58b are respectively supplied to the control unit 9. Since other configurations are the same as those of the second embodiment, the description thereof is omitted.

Next, a control method by the control unit 9 in the case of using a nitrification rate meter 58 including a pair of first ammonia meter 58a and second ammonia meter 58b as denitrification confirmation means will be described. First, the first ammonia meter 58a and the second ammonia meter 58b measure the first ammonia concentration NH1 and the second ammonia concentration NH2, respectively. Each of the first ammonia concentration NH1 and the second ammonia concentration NH2 is supplied to the control unit 9. The controller 9 calculates the measured nitrification rate from the supplied first ammonia concentration NH1 and second ammonia concentration NH2 (NH1> NH2). Specifically, the measured nitrification rate is calculated from the ammonia concentration NH1 measured by the first ammonia meter 58a on the upstream side and the ammonia concentration NH2 on the downstream side based on the equation (11). The measured nitrification speed corresponds to the absolute value of the slope of the solid line shown in FIG. 9B, and the measured nitrification speed may vary as shown by two solid lines depending on the installation position of the nitrification speed meter 58.

On the other hand, a final ammonia concentration (target ammonia concentration) NH3 as a treatment water target value is set in advance for each of various reaction tanks 2A. The control unit 9 calculates a reference nitrification rate (target nitrification rate) from the target ammonia concentration NH ₃ and the ammonia concentration NH1 measured at the position of the first ammonia meter 58a. Store in a recording area (not shown). This target nitrification speed is calculated based on the following equation (12). This target nitrification speed corresponds to the absolute value of the slope of the dotted line shown in FIG. 9B.

As shown in FIG. 9A, the control unit 9 determines that the measured nitrification rate between the first ammonia meter 58a and the second ammonia meter 58b, that is, the measured nitrification rate measured by the nitrification rate meter 58 is the target. At least the gas supply amount from the air diffuser 6 upstream of the second ammonia meter 58b is controlled so as to be less than the nitrification rate. Thereby, the progress of the nitrification reaction on the upstream side of the second ammonia meter 58b can be suppressed, and the denitrification reaction in this region can be promoted. Even if the measured nitrification rate is less than the target nitrification rate, if it becomes too slow, the ammonia concentration may not decrease to the desired target ammonia concentration NH ₃ on the outflow side of the reaction tank 2. Therefore, according to the knowledge obtained from the experiment of the present inventor, it is preferable that the measured nitrification rate is larger than half of the target nitrification rate. That is, the control unit 9 controls the gas supply amount from the air diffusion unit 6 so that the following expression (13) is satisfied.

  Specifically, when the measured nitrification rate with respect to the target nitrification rate is larger than the range set by the equation (13), that is, when the measured nitrification rate is equal to or higher than the target nitrification rate, the nitrification reaction proceeds. It will be too much. Therefore, the controller 9 reduces the amount of air supplied from the air diffusers 6a and 6b at least upstream of the second ammonia meter 58b along the flow direction of the water to be treated in the reaction tank 2A. Thereby, the control unit 9 controls the reaction tank 2 so that the nitrification reaction does not proceed excessively. On the other hand, when the measured nitrification rate with respect to the target nitrification rate is smaller than the range set by the equation (13), that is, when the measured nitrification rate is less than half of the target nitrification rate, the nitrification reaction is suppressed. It will be too much. Therefore, the controller 9 increases the amount of air supplied from the air diffusers 6a and 6b at least upstream of the second ammonia meter 58b along the flow direction of the water to be treated in the reaction tank 2. Thereby, the control part 9 controls so that nitrification reaction may be performed with the desired nitrification speed in the reaction tank 2A.

  In the modification 6 demonstrated above, control of the denitrification process performed with the nitric acid meter in embodiment mentioned above is performed using a pair of ammonia meter. Thereby, in the reaction tank 2A, nitrifying bacteria of aerobic bacteria and facultative anaerobic denitrifying bacteria can coexist and their activities can be activated together. As a result, the nitrification reaction and the denitrification reaction can coexist with good controllability in the reaction tank 2A.

  As mentioned above, although embodiment of this invention was described concretely, this invention is not limited to the above-mentioned embodiment, Various deformation | transformation based on the technical idea of this invention is possible. For example, the numerical values given in the above embodiment are merely examples, and different numerical values may be used as necessary.

  In the above embodiment, biological treatment of nitrogen-containing water by the so-called standard activated sludge method has been described. However, the present invention is not necessarily limited to this method, and various treatment methods using an aerobic tank. Can be applied to. Specifically, the present invention relates to AO (anaerobic-aerobic) method, A2O (anaerobic-anoxic-aerobic) method, nitrification + endogenous denitrification method, multi-step inflow nitrification denitrification method, and multi-step inflow A2O. The present invention can be applied to various methods for treating nitrogen-containing water using an aerobic tank.

  Further, as the reaction tanks 2A, 2B, 2C, etc., it is also possible to adopt a deep tank swirl flow reaction tank having a depth of about 10 m or a shallow tank reaction tank having a depth of about 5 m.

  Moreover, in the above-described embodiment, the control unit and the gas supply amount control unit are separated, but these control unit and the gas supply amount control unit can also be configured from the same control unit, It is also possible to configure three or more separate bodies having similar functions.

Moreover, although the reaction tank 2 by 2nd Embodiment is used in the above-mentioned modified examples 6 and 7, in the modified examples 6 and 7, it is also possible to employ | adopt the reaction tank 2A in the modified examples 2-5. . In this case, by installing a meter installed in the denitrification region and a meter installed in the nitrification region in the nitrification region and the denitrification region that have been confirmed to be formed in each reaction tank 2A, respectively. The same effect as that of the embodiment can be obtained.

Further, in the above-described modified example 6, the nitrification rate meter is composed of a plurality of ammonia meters, specifically a pair of ammonia meters, and the nitrification rate in the water to be treated in the reaction tank 2 is determined using this nitrification rate meter. Although the nitrification rate meter is measured, the nitrification rate meter is not necessarily limited to a pair of ammonia meters. Even if three or more ammonia meters are employed, various devices capable of measuring the nitrification rate may be employed. good.

1 First sedimentation tank 2A One of a plurality of reaction tanks 2B, 2C Other reaction tanks 2a, 2b, 2c, 2d Aerobic tank 3 Solid-liquid separation tank 4a Separation liquid 4b Activated sludge 5 Sludge return path 6, 6a, 6b, 6c, 6d, 16a, 16b, 16c, 26a, 26b, 26c, 26d, 26e, 36, 46 Air diffuser 7 Nitric acid meter 8 Blower 9 Controller 10, 10a, 10b, 10c, 10d, 19a, 19b, 19c, 29a, 29b, 29c, 29d, 29e, 39, 49 Gas supply control unit 11 Ammonia meter 12 Anaerobic tank 12a Motor 12b Stirring unit 13 Partition plate 31 Aerobic region 32 Anoxic anaerobic region 43 Carrier 43a Outer region 43b Inner region 58 Nitrification rate meter 58a First ammonia meter 58b Second ammonia meter 61 Flow rate control means 67, 71 DO meter 81 Upstream desorption Nitrogen section 82 Downstream nitrification section 83 Section 84 until the aeration effect due to aeration is manifested Section 84 Control of the aeration means due to the denitrification confirmation means is performed 85 Control of the aeration means due to the nitrification confirmation means Section to be performed

Claims (5)

A plurality of reaction vessels of the same type connected in parallel;
Flow rate control means for controlling the flow rate of nitrogen-containing water flowing into each reaction tank to be the same;
In each reaction tank, ammonia contained in the nitrogen-containing water is nitrified into nitric acid according to the flow of nitrogen-containing water, and each desired ratio of nitric acid is denitrified at each position along the flow direction of the nitrogen-containing water. Aeration means for supplying gas over substantially the entire region of the flow direction to the nitrogen-containing water,
An upstream denitrification section for obtaining a minimum amount of denitrification nitrogen along the flow direction of the nitrogen-containing water in any one of the plurality of reaction tanks, and the upstream denitrification section Is provided at a first predetermined position between the downstream nitrification section for obtaining the finally required nitrified water quality connected to the downstream side of the first nitrile, and a desired ratio of nitric acid is denitrified at the first predetermined position. Denitrification confirmation means for confirming the denitrification state of whether or not
Whether or not a desired proportion of ammonia is nitrified at the second predetermined position, which is provided downstream of the downstream nitrification section of the reaction tank provided with the denitrification confirmation means. Nitrification confirmation means for confirming the nitrification state;
Based on the denitrification state confirmed by the denitrification confirmation means, the denitrification along the flow direction of the nitrogen-containing water so that a desired ratio of the nitric acid is denitrified at the first predetermined position. The amount of gas supplied by the air diffuser is controlled in the section where the air diffuser is controlled by the denitrifier confirmer including at least the upstream side of the nitrogen confirmer, and confirmed by the nitrification confirmer. Control of aeration means due to the denitrification confirmation means along the flow direction of the nitrogen-containing water so that a desired ratio of the ammonia is nitrified at the second predetermined position based on the nitrification state In the section in which the control of the aeration means caused by the nitrification confirmation means is performed, which is the section following the section where the nitrification confirmation means is included. A first gas supply amount control means for controlling the supply amount of that gas,
Same as the first predetermined position in each reaction tank in the section where the control of the air diffuser due to the denitrification confirming means except the section until the air diffuser effect is exhibited by the air diffuser. The third predetermined position corresponding to the first predetermined position and the same position as the second predetermined position in the section in which the aeration means due to the nitrification confirmation means is controlled or Means for measuring the amount of dissolved oxygen in the nitrogen-containing water at different positions and corresponding to the second predetermined position, respectively, at the third predetermined position and the fourth predetermined position; ,
Based on the respective dissolved oxygen amounts measured at the third predetermined position and the fourth predetermined position of the reaction tank provided with the denitrification confirmation means and the nitrification confirmation means, the denitrification confirmation means and the nitrification confirmation Means for setting a dissolved oxygen target concentration at each of the third predetermined position and the fourth predetermined position in a reaction tank other than the reaction tank provided with the means;
The denitrification of the reaction tank so that the measured value of dissolved oxygen in the third predetermined position of the reaction tank other than the reaction tank provided with the denitrification confirmation means and the nitrification confirmation means matches the target concentration. A reaction tank other than the reaction tank provided with the denitrification confirmation means and the nitrification confirmation means, as well as controlling the gas supply amount by the aeration means in the section in which the control of the aeration means due to the confirmation means is performed The measured value of the dissolved oxygen at the fourth predetermined position of the reaction tank is controlled so that the gas diffused by the air diffuser is controlled in the section where the air diffuser is controlled by the nitrification confirmation device of the reaction tank. A second gas supply amount control means for controlling the supply amount;
An apparatus for treating nitrogen-containing water, comprising: A flow rate control step for controlling the flow rate of nitrogen-containing water flowing into a plurality of reaction tanks of the same type connected in parallel to be the same;
A biological treatment step for performing biological treatment by nitrification reaction and denitrification reaction on nitrogen-containing water flowing in each reaction tank;
Ammonia contained in the nitrogen-containing water is nitrified into nitric acid according to the flow of the nitrogen-containing water in each reaction tank, and each desired proportion of nitric acid is denitrified at each position along the flow direction of the nitrogen-containing water. An air diffusion step for supplying a gas over substantially the entire region in the flow direction to the nitrogen-containing water;
An upstream denitrification section for obtaining a minimum amount of denitrification nitrogen along the flow direction of the nitrogen-containing water in any one of the plurality of reaction tanks, and the upstream denitrification section The desired ratio of nitric acid is denitrified at the first predetermined position in the first predetermined position, which is between the downstream nitrification section for obtaining the finally required nitrified water quality connected to the downstream side of A denitrification confirmation step for confirming the denitrification state of whether or not
A nitrification confirmation step for confirming a nitrification state of whether or not a desired ratio of ammonia is nitrified at a second predetermined position on the downstream side in the downstream nitrification section of the reaction tank in which the denitrification state is confirmed;
Based on the denitrification state confirmed in the denitrification confirmation step, the first along the flow direction of the nitrogen-containing water so that a desired ratio of the nitric acid is denitrified at the first predetermined position. And controlling the gas supply amount in the section where the control of the diffuser means caused by the denitrification confirmation means, including at least the upstream side of the predetermined position, and based on the nitrification state confirmed in the nitrification confirmation step , Following the section in which the control of the aeration means due to the denitrification confirmation means is performed along the flow direction of the nitrogen-containing water so that the desired proportion of ammonia is nitrified at the second predetermined position Gas produced by the air diffuser in a section where the air diffuser is controlled due to the nitrification confirmation device, including at least the upstream side of the second predetermined position. A first gas supply amount control step of controlling the supply amount,
The first predetermined in each reaction tank in a section where the control of the aeration means due to the denitrification confirmation means excluding the section until the aeration effect is manifested by the aeration in the aeration step. A third predetermined position corresponding to the first predetermined position that is the same position as or different from the position, and the second predetermined position in a section in which the control of the aeration means caused by the nitrification confirmation means is performed A dissolved oxygen measurement step of measuring the amount of dissolved oxygen at a fourth predetermined position which is the same position or a different position and corresponds to the second predetermined position;
Reaction in which the denitrification state and the nitrification state are confirmed based on the measured values of the dissolved oxygen concentration measured at the third predetermined position and the fourth predetermined position in the reaction tank in which the denitrification state and the nitrification state are confirmed. A dissolved oxygen target concentration setting step for setting a dissolved oxygen target concentration at each of the third predetermined position and the fourth predetermined position of the reaction tank other than the tank;
In the denitrification confirmation unit of the reaction tank, the measured value of dissolved oxygen in the third predetermined position of the reaction tank other than the reaction tank in which the denitrification state and the nitrification state are confirmed matches the target concentration. The fourth predetermined amount of the reaction tank other than the reaction tank in which the denitrification state and the nitrification state are confirmed is controlled while controlling the gas supply amount by the air diffusion means in the section in which the control of the resulting air diffusion means is performed. A gas for controlling the amount of gas supplied by the air diffuser in the section where the air diffuser is controlled by the nitrification confirmation device of the reaction tank so that the measured value of dissolved oxygen at the position matches the target concentration A second gas supply control step for supply control;
A method for treating nitrogen-containing water, comprising: The flow rate of the nitrogen-containing water is controlled to be the same, among the plurality of reaction tanks of the same type connected in parallel, in any one reaction tank, along the flow direction of the nitrogen-containing water, Between the upstream denitrification section for obtaining the minimum necessary denitrification amount and the downstream nitrification section for obtaining the finally required nitrification water quality connected to the downstream side of the upstream denitrification section A denitrification confirming means for confirming a denitrification state of whether or not a desired ratio of nitric acid is denitrified provided at a first predetermined position; and a second denitrification confirmation means downstream of the downstream nitrification section The nitrification confirmation means for confirming the nitrification state of whether or not the desired ratio of ammonia is nitrified at the second predetermined position is provided at the predetermined position, and according to the flow of nitrogen-containing water in each reaction tank The nitrogen-containing water contains Monia is nitrified into nitric acid, and a gas is passed over the entire area in the flow direction with respect to the nitrogen-containing water so that each desired proportion of nitric acid is denitrified at each position along the flow direction of the nitrogen-containing water. Same as the first predetermined position in the section in which the control of the aeration means caused by the denitrification confirmation means excluding the section until the aeration effect by the aeration means is expressed, and the aeration means to be supplied The third predetermined position corresponding to the first predetermined position and the same position as the second predetermined position in the section in which the aeration means due to the nitrification confirmation means is controlled or Dissolved oxygen that is provided at a fourth predetermined position corresponding to the second predetermined position and that measures different amounts of dissolved oxygen in the nitrogen-containing water at the third predetermined position and the fourth predetermined position. Quantity measuring hand In the case of having, a control apparatus of the air diffuser means to be used for the air diffuser unit,
Based on the denitrification state confirmed by the denitrification confirmation means, the denitrification along the flow direction of the nitrogen-containing water so that a desired ratio of the nitric acid is denitrified at the first predetermined position. The amount of gas supplied by the air diffuser is controlled in the section where the air diffuser is controlled by the denitrifier confirmer including at least the upstream side of the nitrogen confirmer, and confirmed by the nitrification confirmer. Control of aeration means due to the denitrification confirmation means along the flow direction of the nitrogen-containing water so that a desired ratio of the ammonia is nitrified at the second predetermined position based on the nitrification state In the section in which the control of the aeration means caused by the nitrification confirmation means is performed, which is the section following the section where the nitrification confirmation means is included. A first gas supply amount control means for controlling the supply amount of that gas,
Based on the respective dissolved oxygen amounts measured at the third predetermined position and the fourth predetermined position of the reaction tank provided with the denitrification confirmation means and the nitrification confirmation means, the denitrification confirmation means and the nitrification confirmation Means for setting a dissolved oxygen target concentration at each of the third predetermined position and the fourth predetermined position in a reaction tank other than the reaction tank provided with the means;
The denitrification of the reaction tank so that the measured value of dissolved oxygen in the third predetermined position of the reaction tank other than the reaction tank provided with the denitrification confirmation means and the nitrification confirmation means matches the target concentration. A reaction tank other than the reaction tank provided with the denitrification confirmation means and the nitrification confirmation means, as well as controlling the gas supply amount by the aeration means in the section in which the control of the aeration means due to the confirmation means is performed The measured value of the dissolved oxygen at the fourth predetermined position of the reaction tank is controlled so that the gas diffused by the air diffuser is controlled in the section where the air diffuser is controlled by the nitrification confirmation device of the reaction tank. A second gas supply amount control means for controlling the supply amount;
An air diffuser control apparatus comprising: The flow rate of the nitrogen-containing water is controlled to be the same, among the plurality of reaction tanks of the same type connected in parallel, in any one reaction tank, along the flow direction of the nitrogen-containing water, Between the upstream denitrification section for obtaining the minimum necessary denitrification amount and the downstream nitrification section for obtaining the finally required nitrification water quality connected to the downstream side of the upstream denitrification section A denitrification confirming means for confirming a denitrification state of whether or not a desired ratio of nitric acid is denitrified provided at a first predetermined position; and a second denitrification confirmation means downstream of the downstream nitrification section The nitrification confirmation means for confirming the nitrification state of whether or not the desired ratio of ammonia is nitrified at the second predetermined position is provided at the predetermined position, and according to the flow of nitrogen-containing water in each reaction tank The nitrogen-containing water contains Monia is nitrified into nitric acid, and a gas is passed over the entire area in the flow direction with respect to the nitrogen-containing water so that each desired proportion of nitric acid is denitrified at each position along the flow direction of the nitrogen-containing water. Same as the first predetermined position in the section in which the control of the aeration means caused by the denitrification confirmation means excluding the section until the aeration effect by the aeration means is expressed, and the aeration means to be supplied The third predetermined position corresponding to the first predetermined position and the same position as the second predetermined position in the section in which the aeration means due to the nitrification confirmation means is controlled or Dissolved oxygen that is provided at a fourth predetermined position corresponding to the second predetermined position and that measures different amounts of dissolved oxygen in the nitrogen-containing water at the third predetermined position and the fourth predetermined position. Quantity measuring hand When having a control method of an air diffuser means to be used for the air diffuser unit,
Based on the denitrification state confirmed by the denitrification confirmation means, the denitrification along the flow direction of the nitrogen-containing water so that a desired ratio of the nitric acid is denitrified at the first predetermined position. The amount of gas supplied by the air diffuser is controlled in the section where the air diffuser is controlled by the denitrifier confirmer including at least the upstream side of the nitrogen confirmer, and confirmed by the nitrification confirmer. Control of aeration means due to the denitrification confirmation means along the flow direction of the nitrogen-containing water so that a desired ratio of the ammonia is nitrified at the second predetermined position based on the nitrification state In the section in which the control of the aeration means caused by the nitrification confirmation means is performed, which is the section following the section where the nitrification confirmation means is included. A first gas supply amount control step of controlling the supply amount of the gas that,
Based on the respective dissolved oxygen amounts measured at the third predetermined position and the fourth predetermined position of the reaction tank provided with the denitrification confirmation means and the nitrification confirmation means, the denitrification confirmation means and the nitrification confirmation Setting a dissolved oxygen target concentration at each of the third predetermined position and the fourth predetermined position in a reaction tank other than the reaction tank provided with the means;
The denitrification of the reaction tank so that the measured value of dissolved oxygen in the third predetermined position of the reaction tank other than the reaction tank provided with the denitrification confirmation means and the nitrification confirmation means matches the target concentration. A reaction tank other than the reaction tank provided with the denitrification confirmation means and the nitrification confirmation means, as well as controlling the gas supply amount by the aeration means in the section in which the control of the aeration means due to the confirmation means is performed The measured value of the dissolved oxygen at the fourth predetermined position of the reaction tank is controlled so that the gas diffused by the air diffuser is controlled in the section where the air diffuser is controlled by the nitrification confirmation device of the reaction tank. A second gas supply amount control step for controlling the supply amount;
A method for controlling the air diffusing means. A flow rate control step for controlling the flow rate of nitrogen-containing water flowing into a plurality of reaction tanks of the same type connected in parallel to be the same;
An upstream denitrification section for obtaining a minimum amount of denitrification nitrogen along the flow direction of the nitrogen-containing water in any one of the plurality of reaction tanks, and the upstream denitrification section The desired ratio of nitric acid is denitrified at the first predetermined position in the first predetermined position, which is between the downstream nitrification section for obtaining the finally required nitrified water quality connected to the downstream side of A denitrification confirmation step for confirming the denitrification state of whether or not
A nitrification confirmation step for confirming a nitrification state of whether or not a desired ratio of ammonia is nitrified at a second predetermined position on the downstream side in the downstream nitrification section of the reaction tank in which the denitrification state is confirmed;
Based on the denitrification state confirmed in the denitrification confirmation step, the first along the flow direction of the nitrogen-containing water so that a desired ratio of the nitric acid is denitrified at the first predetermined position. The amount of gas supplied from the air diffuser in the section where the air diffuser is controlled due to the denitrification confirming unit including at least the upstream side of the predetermined position is controlled and confirmed in the nitrification confirming step. Based on the nitrification state, the control of the aeration means caused by the denitrification confirmation means along the flow direction of the nitrogen-containing water is performed so that the desired ratio of the ammonia is nitrified at the second predetermined position. The aeration in the section that follows the section to be performed and in which the control of the aeration means due to the nitrification confirmation means including at least the upstream side from the second predetermined position is performed. A first gas supply amount control step of controlling the supply amount of the gas from stage,
The first predetermined in each reaction tank in a section where the control of the aeration means due to the denitrification confirmation means excluding the section until the aeration effect is manifested by the aeration in the aeration step. A third predetermined position corresponding to the first predetermined position that is the same position as or different from the position, and the second predetermined position in a section in which the control of the aeration means caused by the nitrification confirmation means is performed A dissolved oxygen measurement step of measuring the amount of dissolved oxygen at a fourth predetermined position which is the same position or a different position and corresponds to the second predetermined position;
Reaction in which the denitrification state and the nitrification state are confirmed based on the measured values of the dissolved oxygen concentration measured at the third predetermined position and the fourth predetermined position in the reaction tank in which the denitrification state and the nitrification state are confirmed. A dissolved oxygen target concentration setting step for setting a dissolved oxygen target concentration at each of the third predetermined position and the fourth predetermined position of the reaction tank other than the tank;
In the denitrification confirmation unit of the reaction tank, the measured value of dissolved oxygen in the third predetermined position of the reaction tank other than the reaction tank in which the denitrification state and the nitrification state are confirmed matches the target concentration. The fourth predetermined amount of the reaction tank other than the reaction tank in which the denitrification state and the nitrification state are confirmed is controlled while controlling the gas supply amount by the air diffusion means in the section in which the control of the resulting air diffusion means is performed. A gas for controlling the amount of gas supplied by the air diffuser in the section where the air diffuser is controlled by the nitrification confirmation device of the reaction tank so that the measured value of dissolved oxygen at the position matches the target concentration A second gas supply control step for controlling gas supply;
A computer-readable recording medium on which a program is recorded.

Images