JP6499389B2 - Waste water treatment apparatus and waste water treatment method - Google Patents

Description

The present invention relates to an apparatus for treating nitrogen-containing water, a method for treating nitrogen-containing water, a system for treating nitrogen-containing water, a control apparatus, a control method, and a program, which control aeration air volume in an aerobic tank.
Background art

  Heretofore, various sewage treatment systems have been put to practical use as sewage treatment systems for treating sewage such as living nitrogen-containing water or factory nitrogen-containing water, such as those according to the standard activated sludge method or those according to the water filtration filter method.

  In a sewage treatment system based on the standard activated sludge method, aeration treatment is performed to supply oxygen to various types of aerobic microorganisms present in the reaction tank while allowing sewage to be treated to flow into the reaction tank. By this, the organic substance contained in the sewage in a reaction tank is decomposed | disassembled by the effect | action of an aerobic microbe, and the 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 aeration device that performs aeration. Inflow water proportional control is control which supplies air of the quantity proportional to the amount of inflowing water which flows into a reaction tank to a diffuser using the flowmeter installed in the inflow side of a reaction tank. The DO control measures the dissolved oxygen concentration using a dissolved oxygen meter (DO meter) installed at the end of the outflow side of the reaction tank, and air is supplied to the diffuser so as to maintain the dissolved oxygen concentration at a predetermined concentration. It is control to supply. Ammonia control supplies air to the diffuser so as to maintain ammonia nitrogen (NH ₄ -N) at the end of the reaction vessel at a predetermined concentration using an ammonia meter installed at the end of the reaction vessel on the outflow side Control.

However, the various controls described above have the following problems.
That is, in the inflow water proportional control, since the organic substance load and the ammonia load of the inflow water containing nitrogen are changed and the water quality fluctuates, if the air amount is controlled in proportion to the inflow water amount, the air amount will be excessive I will. Moreover, in DO control, the organic substance load and ammonia load of influent water containing nitrogen change, and when these loads decrease, the amount of air tends to be excessive, and conversely, the amount of air is insufficient when the load increases It becomes easy to do. Furthermore, in the ammonia control, while an appropriate amount of air can be supplied to the aeration device according to the ammonia load of the inflowing water containing nitrogen, the denitrification treatment may be performed in a stage before the ammonia control. It was difficult.

  In order to solve the above problems, the inventors of the present invention nitrify ammonia contained in nitrogen-containing water to nitric acid according to the flow of nitrogen-containing water in a reaction tank, and nitric acid at each position along the flow direction of nitrogen-containing water A diffuser for supplying a gas over substantially the entire flow direction to the nitrogen-containing water so that each desired ratio of the nitrogen oxides is denitrified, and a first predetermined position in the flow direction of the nitrogen-containing water, Denitrification confirmation means for confirming whether or not the desired ratio of nitric acid generated at the first predetermined position is denitrified, and second predetermined on the downstream side of the denitrification confirmation means along the flow direction of the nitrogen-containing water Nitrification confirmation means provided at the position for confirming whether or not the desired proportion of ammonia is nitrified, and the proportion of nitric acid generated by nitrification at the first predetermined position confirmed by the denitrification confirmation means, Nitrogen so that the desired proportion of nitric acid is denitrified According to the proportion of ammonia at the second predetermined position confirmed by the nitrification confirmation means, while controlling the amount of gas supplied by the aeration means at least upstream of the denitrification confirmation means along the flow direction of the water, Nitrogen supply control means for controlling the supply amount of gas from the aeration means at least upstream of the nitrification confirmation means along the flow direction of the nitrogen-containing water so that the desired proportion of ammonia is nitrified The treatment apparatus and treatment method of contained water were proposed (patent documents 2, 3).

  According to the above-described apparatus and method for treating nitrogen-containing water, the reaction vessel is properly controlled by appropriately controlling the gas supply amount (aeration amount) according to the load of nitrogen-containing water flowing into the reaction vessel where aeration is performed. While being able to supply a quantity of oxygen, denitrification treatment and nitrification treatment can be appropriately controlled, nitrogen removal rate can be improved, and treated water quality can be improved.

  However, due to various reasons, nitrogen-containing sewage treatment facilities often use a plurality of reaction vessels of the same type connected in parallel, and when the above treatment is carried out in such facilities, It was necessary to provide denitrification confirmation means and nitrification confirmation means in the reaction tank together with the diffusion means. 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 become expensive.

  Therefore, it is possible to use a relatively inexpensive dissolved oxygen meter (DO meter) instead of the expensive ammonia detector or nitric acid detector, but the dissolved oxygen meter does not detect ammonia or nitric acid directly. Therefore, there has been a problem that it is difficult to control the detonating means with high accuracy, to cause overexplosion, or to achieve desired water quality with high reliability.

JP 2005-199116 A Japanese Patent Application No. 2012-053782 Japanese Patent Application No. 2012-053784

  When the present inventor controls the detonation means so that appropriate denitrification and nitrification can be performed using an ammonia detector or a nitric acid detector, the amount of dissolved oxygen in the reaction tank has a specific distribution. The present invention has been accomplished.

The apparatus for treating nitrogen-containing water of the present invention is as follows.
(1) a plurality of reaction vessels of the same type connected in parallel;
Flow control means for controlling the flow of nitrogen-containing water flowing into each reaction tank to be the same;
Ammonia contained in the nitrogen-containing water is nitrated to nitric acid according to the flow of nitrogen-containing water in each reaction tank so that each desired ratio of nitric acid is denitrified at each position along the flow direction of the nitrogen-containing water A diffuser for supplying a gas to the nitrogen-containing water over substantially the entire flow direction;
In any one reaction vessel of the plurality of reaction vessels, an upstream denitrifying section for obtaining a minimum necessary denitrifying nitrogen amount along the flow direction of the nitrogen-containing water, and the upstream denitrifying section Whether or not the desired proportion of nitric acid is denitrified at an intermediate position between the downstream side nitrification zone for obtaining the final required nitrification water quality to be connected downstream of Denitrification confirmation means to confirm the state of denitrification;
The denitrification confirming means along the flow direction of the nitrogen-containing water so that the desired proportion of the nitric acid is denitrified at the halfway position based on the denitrification state confirmed by the denitrification confirming means First gas supply amount control means for controlling the supply amount of gas by the aeration means in a section where the control of the aeration means caused by the denitrification confirmation means, including at least the upstream side, is performed;
The same position or different position in the middle of each reaction tank, in the section where the control of the aeration means caused by the denitrification confirmation means is performed excluding the section until the aeration effect by the aspiration means appears A means for measuring the dissolved oxygen amount of the nitrogen-containing water provided at a predetermined position corresponding to the halfway position which is the position;
Each reaction vessel other than the reaction vessel provided with the denitrification confirming means based on the dissolved oxygen amount measured by the dissolved oxygen measuring means provided at the predetermined position of the reaction vessel provided with the denitrification confirming means Means for setting a dissolved oxygen target concentration at the predetermined position of
Aeration due to the denitrification confirming means of the reaction vessel such that the measured value of the dissolved oxygen at the predetermined position of the reaction vessel other than the reaction vessel provided with the denitrification confirming means matches the target concentration Second gas supply control means for controlling the supply amount of gas by the aeration means in a section where control of the means is performed;
And the like.

(2) a plurality of reaction vessels of the same type connected in parallel;
Flow control means for controlling the flow of nitrogen-containing water flowing into each reaction tank to be the same;
Ammonia contained in the nitrogen-containing water is nitrated to nitric acid according to the flow of nitrogen-containing water in each reaction tank so that each desired ratio of nitric acid is denitrified at each position along the flow direction of the nitrogen-containing water A diffuser for supplying a gas to the nitrogen-containing water over substantially the entire flow direction;
In any one reaction vessel of the plurality of reaction vessels, an upstream denitrifying section for obtaining a minimum necessary denitrifying nitrogen amount along the flow direction of the nitrogen-containing water, and the upstream denitrifying section Provided on the first to n (n is a natural number of 2 or more) at a predetermined position between the downstream side and the downstream side nitrification section to obtain the final necessary nitrification water quality. Denitrification confirmation means for respectively confirming the denitrification state as to whether or not the desired proportion of the nitric acid is denitrified at the first to nth predetermined positions;
The nitrogen so that the nitric acid is denitrified at each desired ratio at the first to n-th predetermined positions based on the denitrification states confirmed by the first to n-th predetermined positions of the denitrification confirmation means. Control of the aeration means caused by the denitrifying confirmation means at the first to n predetermined positions including at least the upstream side of each of the first to n predetermined positions along the flow direction of the contained water is performed First gas supply amount control means for controlling the supply amount of gas by the aeration means in each section;
Control of the aeration means caused by the denitrification confirmation means at each of the first to n-th predetermined positions except for the section until the aeration effect of the aeration means appears in each reaction tank is performed Provided at each predetermined position of the 1a to na corresponding to the first to n predetermined positions which are the same position as or different from the first to n predetermined positions in each section, respectively; A means for respectively measuring the dissolved oxygen amount of the nitrogen-containing water at each predetermined position;
Based on the amount of dissolved oxygen measured at each predetermined position of the first to the first reaction vessels provided with the denitrification confirmation means, the reaction vessels other than the reaction vessels provided with the denitrification confirmation means A means for individually setting a dissolved oxygen target concentration at each predetermined position of the first to na;
The first to the first of the reaction vessels such that the measured value of the dissolved oxygen at each predetermined position of the first to na of the reaction vessels other than the reaction vessel provided with the denitrification confirmation means matches the target concentration. second gas supply amount control means for controlling the supply amount of gas by the aeration means in each section where control of the aeration means due to the denitrification confirmation means at the predetermined position of n is performed;
And the like.

  In the present invention, the “upstream denitrification zone” is (1) an environmental state in which the amount of dissolved oxygen contained in the nitrogen-containing water gradually becomes rich from the upstream side to the downstream side in the reaction tank If it is possible to confirm that the desired proportion of nitric acid is denitrified at an intermediate position in the flow direction of the nitrogen-containing water, assuming that such an environmental condition is a precondition, the desired position of nitric acid upstream from the intermediate position is confirmed. It can be estimated that the section in which the ratio is denitrified can be secured continuously, and (2) the length of the continuous section in which the desired ratio of nitric acid is denitrified on the upstream side from the intermediate position becomes long The amount of denitrifying nitrogen which is to be denitrified by the intermediate position following the relationship is increased, (3) and is dissipated into the atmosphere by denitrifying the desired proportion of nitric acid once The nitrogen molecule that was A section in a reaction tank along a flow direction of nitrogen-containing water, which is determined in view of never returning to the presence of water, denitrification confirmed by denitrification confirmation means installed at a position immediately after the section If the amount of gas supplied by the aeration means is controlled so that the desired denitrification state on the upstream side of the installation position is maintained based on the state, the minimum denitrifying nitrogen amount 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.

  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 on the upstream side of the installation position is maintained Together with the environmental conditions in the reaction tank gradually becoming rich, the section (82 in FIG. 1A) where it is expected that the necessary nitrification water quality will be finally obtained. As described above, the “downstream nitrification section” is a section in which the nitrification state is confirmed by the nitrification confirmation means, and the denitrification reaction occurs also in this section.

  In the present invention, “a section until the aeration effect appears due to aeration” refers to a section in which no significant change occurs in the measured value when aeration is performed from the aeration means, taking into account the measurement error of the instruments used. This is because the control with the required accuracy can not be made even if it is measured in such a section at 83) in 1A.

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

  In the apparatus for treating nitrogen-containing water according to the present invention, in the above-mentioned invention, the diffusing means comprises an area where the nitrification reaction is performed and an area where the denitrification reaction is performed according to the passage of time or the flow direction of the nitrogen-containing water. It is characterized in that it is configured to be able to supply a gas so as to form the gas sequentially, alternately, or repeatedly.

  In the apparatus for treating nitrogen-containing water according to the present invention, in the above-mentioned invention, when the gas supply amount control means can not confirm a desired ratio of denitrification to nitric acid generated by nitrification reaction by the denitrification confirmation means, Controlling increase or decrease of the gas supply amount by the aeration means at least upstream of the denitrification confirmation means along the flow direction of the nitrogen-containing water, or the gas supply amount control means controls the flow rate of the nitrogen-containing water Among the respective predetermined positions from the first predetermined position to the n-th predetermined position, the denitrification confirmation means can not confirm a desired ratio of denitrification to nitric acid at the first predetermined position along the flow direction of the nitrogen-containing water The amount of gas supplied by the aeration means at least on the upstream side of the first predetermined position is controlled to increase or decrease, and at the i-th predetermined position (i: natural number not less than 2 and not more than n) If the denitrification confirmation means can not confirm the proportion of denitrification, the amount of gas supplied by the aeration means between at least the i-th predetermined position and the (i-1) -th predetermined position is controlled to increase or decrease I assume.

  In the nitrogen-containing water treatment apparatus according to the present invention, in the above-mentioned invention, the denitrification confirmation means is a nitric acid concentration measuring means configured to be capable of measuring the nitric acid concentration, and a desired ratio of nitric acid is denitrified or not. The concentration of nitric acid measured by the nitric acid concentration measuring means at each predetermined position from the first predetermined position to the nth predetermined position is determined by measuring the nitric acid concentration. Aeration means on the upstream side of the first predetermined position and an ith predetermined position (i: 2 or more and n or less) along the flow direction of the nitrogen-containing water so as to be within the predetermined range set by the predetermined position It is characterized in that the supply amount of gas from at least one aeration means selected from the aeration means between the natural number) and the (i-1) th predetermined position is controlled.

  In the nitrogen-containing water treatment apparatus according to the present invention, in the above-mentioned invention, the denitrification confirmation means is an ammoniacal nitrogen measurement means configured to be capable of measuring ammoniacal nitrogen, and a desired ratio of ammoniacal nitrogen is denitrification It is confirmed by measuring the ammoniacal nitrogen concentration whether or not it has been used, and the gas supply amount control means at least contains nitrogen so that the nitric acid concentration measured by the ammoniacal nitrogen measurement means falls within a predetermined range. It is characterized in that the supply amount of gas from the aeration means on the upstream side of the ammoniacal nitrogen measurement means along the flow direction of water is controlled.

In the apparatus for treating nitrogen-containing water according to the present invention, in the above-mentioned invention, the nitric acid concentration measuring means is disposed at an nth predetermined position from a first nitric acid meter disposed at a first predetermined position. A plurality of nitric acid meters (n: natural number of 2 or more).
Further, in the nitrogen-containing water treatment apparatus according to the present invention, in the above-mentioned invention, the nitric acid concentration measuring means is constituted by at least one nitric acid meter, and from the measurement of the nitric acid concentration of nitrogen-containing water at the first predetermined position, It is characterized by selectively switching and executing up to measurement of the nitric acid concentration of nitrogen-containing water at the n-th predetermined position.

  In the apparatus for treating nitrogen-containing water according to the present invention, in the above-mentioned invention, the gas supply amount control means is at least upstream of the first position in the reaction vessel or the denitrification confirming means in the flow direction of the nitrogen-containing water. On the side, the aeration means is controlled so that the gas supply amount from the aeration means becomes substantially uniform.

  In the apparatus for treating nitrogen-containing water according to the present invention, the gas supply control means is provided from the aeration means in the entire area along the flow direction of the nitrogen-containing water or upstream of the first predetermined position in the reaction tank. It is characterized in that the supply amount of gas is controlled so as to be substantially uniform.

  The apparatus for treating nitrogen-containing water according to the present invention is characterized in that, in the above invention, an anaerobic tank is provided at a front stage of the reaction tank.

Further, the method for treating nitrogen-containing water of the present invention is as follows.
(3) a flow control step of controlling the flow rates of nitrogen-containing water flowing into the plurality of reaction vessels of the same type connected in parallel to be the same;
A biological treatment step of performing biological treatment by nitrification reaction and denitrification reaction on nitrogen-containing water flowing in each reaction vessel;
Ammonia contained in the nitrogen-containing water is nitrated to nitric acid according to the flow of the nitrogen-containing water in each reaction tank, and each desired ratio of nitric acid is denitrified at each position along the flow direction of the nitrogen-containing water Supplying a gas to the nitrogen-containing water over substantially the entire flow direction;
In any one reaction vessel of the plurality of reaction vessels, an upstream denitrifying section for obtaining a minimum necessary denitrifying nitrogen amount along the flow direction of the nitrogen-containing water, and the upstream denitrifying section Between the downstream side and the downstream side nitrification zone for obtaining the finally necessary nitrification water quality downstream, the denitrification whether or not the desired proportion of the nitric acid is denitrified at the midway position at the midway position Denitrification check step to check the status of
Based on the denitrification state confirmed in the denitrification confirmation step, at least upstream from the halfway position along the flow direction of the nitrogen-containing water so that the desired ratio of the nitric acid is denitrified at the halfway position based on the denitrification state confirmed A first gas supply amount control step of controlling a gas supply amount in a section in which the control of the aeration means caused by the denitrification confirmation means is performed, the method including:
The same position as in the middle of each reaction tank, except for the section until the aeration effect is expressed by the aeration in the aeration step, in which the control of the aeration means caused by the denitrification confirmation means is performed A dissolved oxygen measurement step of measuring the amount of dissolved oxygen at a predetermined position which is a position or a different position and corresponds to the intermediate position;
Based on the measured value of the dissolved oxygen concentration measured at the predetermined position in the reaction vessel where the denitrification state and the nitrification state were confirmed, at the predetermined position of another reaction vessel other than the reaction vessel where the denitrification state was confirmed A dissolved oxygen target concentration setting step of setting a dissolved oxygen target concentration;
Dispersion due to the denitrification confirmation means of the reaction vessel such that the measured value of the dissolved oxygen at the predetermined position of the reaction vessel other than the reaction vessel where the denitrification state and the nitrification state are confirmed matches the target concentration A second gas supply control step of controlling a supply amount of gas by the aeration means in a section where the control of the air means is performed;
It is characterized by including.

(4) a flow control step of controlling the flow rates of nitrogen-containing water flowing into the plurality of reaction vessels of the same type connected in parallel to be the same;
A biological treatment step of performing biological treatment by nitrification reaction and denitrification reaction on nitrogen-containing water flowing in each reaction vessel;
Ammonia contained in the nitrogen-containing water is nitrated to nitric acid according to the flow of the nitrogen-containing water in each reaction tank, and each desired ratio of nitric acid is denitrified at each position along the flow direction of the nitrogen-containing water Supplying a gas to the nitrogen-containing water over substantially the entire flow direction;
In any one reaction vessel of the plurality of reaction vessels, an upstream denitrifying section for obtaining a minimum necessary denitrifying nitrogen amount along the flow direction of the nitrogen-containing water, and the upstream denitrifying section In one of the first to n (n is a natural number greater than or equal to 2) predetermined positions, any one of which is located downstream of and downstream of the downstream nitrification section for obtaining the finally necessary nitrification water quality. A denitrification confirmation step of confirming a denitrification state as to whether or not the desired proportion of the nitric acid is denitrified at the first to nth predetermined positions;
Based on the flow direction of the nitrogen-containing water so that each desired ratio of the nitric acid is denitrified at the first to n-th predetermined positions based on the denitrification states confirmed in the denitrification confirmation step. A first gas supply amount for controlling the gas supply amount in each section in which control of the aeration means caused by the denitrification confirmation means is performed, including at least the upstream side of each of the first to n predetermined positions Control step,
In each reaction tank, the first to the first sections in each section where the control of the aeration means caused by the denitrification confirmation means is performed excluding the section until the aeration effect is expressed by the aeration in the aeration step. a dissolved oxygen measuring step of measuring the amount of dissolved oxygen at each of the predetermined positions 1a to na corresponding to the first to n predetermined positions, respectively at the same position as or different from the predetermined positions of n;
Based on the measurement value of the dissolved oxygen concentration measured at each of the predetermined positions of the first to na in the reaction vessel in which the denitrification state is confirmed, the above-mentioned other reaction vessels other than the reaction vessel in which the denitrification state is confirmed A dissolved oxygen target concentration setting step of setting the dissolved oxygen target concentration at each of the first predetermined positions 1a to 1n;
In the first to n-th reaction vessels, the measurement value of the dissolved oxygen at each predetermined position of the first to na of the reaction vessels other than the reaction vessel in which the denitrifying state is confirmed matches the target concentration. A second gas supply control step of controlling the supply amount of gas by the aeration means in each section in which control of the aeration means caused by the denitrification confirmation means at a predetermined position is performed;
It is characterized by including.

  In the method for treating nitrogen-containing water according to the present invention, in the above-mentioned invention, the region in which the nitrification reaction is performed and the region in which the denitrification reaction are sequentially alternated according to the passage of time or the flow direction of the nitrogen-containing water Alternatively, the gas is supplied to the nitrogen-containing water so as to form repeatedly.

  In the method of treating nitrogen-containing water according to the present invention, in the above-mentioned invention, the ratio of nitric acid confirmed in the denitrification confirmation step is the nitric acid concentration at the predetermined position, and the measurement is performed in the denitrification confirmation step in the gas supply control step. It is characterized in that the supply amount of gas at least on the upstream side along the flow direction of the nitrogen-containing water from the predetermined position is controlled in the direction in which the nitric acid concentration falls within the predetermined range.

  In the method of 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 each predetermined position from the first predetermined position to the nth predetermined position, In the gas supply amount control step, at least on the upstream side along the flow direction of the nitrogen-containing water from the first predetermined position in a direction in which the nitric acid concentration at the first predetermined position measured in the denitrification confirmation step falls within the predetermined range. While controlling the supply amount of gas, the nitric acid concentration at the i-th predetermined position (i: natural number not less than 2 and not more than n) measured in the denitrification confirmation step falls within at least the i-th predetermined position The present invention is characterized in that the amount of gas supplied to the nitrogen-containing water is controlled between the (i-1) th predetermined position and the predetermined position.

Moreover, the control apparatus of the aeration means based on this invention is as follows.
(5) In the flow direction of the nitrogen-containing water in any one of a plurality of reaction vessels of the same type connected in parallel and controlled such that the flow rate of the inflowing nitrogen-containing water is the same An upstream denitrifying section for obtaining the minimum necessary denitrifying nitrogen amount, and a downstream nitrification section for obtaining the finally necessary nitrifying water quality downstream of the upstream denitrifying section along the line; And denitrification confirmation means for confirming whether denitrification is being performed or not for the desired proportion of nitric acid provided at an intermediate position between Ammonia contained in the nitrogen-containing water is nitrified to nitric acid, and each desired ratio of nitric acid is denitrified at each position along the flow direction of the nitrogen-containing water with respect to the nitrogen-containing water in the flow direction Aeration means for supplying gas over substantially the entire area, side by side The same intermediate position as the intermediate position in a section where control of the aeration means is performed due to the denitrification confirmation means excluding the section until the aeration effect is expressed by the aeration means, or the intermediate position The aeration used for the aeration means in the case of having the dissolved oxygen amount measuring means for measuring the dissolved oxygen amount of the nitrogen-containing water at the predetermined position corresponding to the halfway position. Control means of the means,
The denitrification confirming means along the flow direction of the nitrogen-containing water so that the desired proportion of the nitric acid is denitrified at the halfway position based on the denitrification state confirmed by the denitrification confirming means First gas supply amount control means for controlling the supply amount of gas by the aeration means in a section where the control of the aeration means caused by the denitrification confirmation means, including at least the upstream side, is performed;
Based on the amount of dissolved oxygen measured at a predetermined position corresponding to the halfway position of the reaction vessel provided with the denitrification confirmation means and the nitrification confirmation means, other than the reaction vessel provided with the denitrification confirmation means A means for respectively setting a dissolved oxygen target concentration at a predetermined position corresponding to the intermediate position of the reaction tank;
The denitrification confirming means of the reaction vessel such that the measured value of the dissolved oxygen at a predetermined position corresponding to the halfway position of the reaction vessel other than the reaction vessel provided with the denitrification confirming means matches the target concentration Second gas supply amount control means for controlling the supply amount of gas by the aeration means in a section in which the control of the aeration means resulting from the control is performed;
And the like.

(6) In the flow direction of the nitrogen-containing water in any one of a plurality of reaction vessels of the same type connected in parallel and controlled such that the flow rate of the inflowing nitrogen-containing water is the same An upstream denitrifying section for obtaining the minimum necessary denitrifying nitrogen amount, and a downstream nitrification section for obtaining the finally necessary nitrification water quality connected downstream of the upstream denitrifying section The denitrification state as to whether or not each desired proportion of nitric acid is denitrified provided at each predetermined position of the first to n (n is a natural number of 2 or more) located in any one of Ammonia contained in the nitrogen-containing water is nitrated to nitric acid according to the flow of nitrogen-containing water in each reaction tank, and it is detected at each position along the flow direction of the nitrogen-containing water. Said nitrogen such that each desired proportion of nitric acid is denitrified Aeration means for supplying gas over substantially the entire flow direction to the presence of water, and removal of the first to n predetermined positions except for a section until the aeration effect is expressed by the aeration means The first to n corresponding to the first to n predetermined positions are the same or different positions as the first to n predetermined positions in each section in which control of the aeration means caused by the nitrogen confirmation means is performed. In the case where the oxygen concentration measuring means is provided at each predetermined position of each of the first to the first predetermined positions to measure the dissolved oxygen amount of the nitrogen-containing water, the diffuser used for the aeration means Control device for air means,
Based on the denitrification states confirmed by the denitrification confirmation means at the first to nth predetermined positions, the desired ratio of the nitric acid is denitrified at each of the first to nth predetermined positions, Control of the aeration means resulting from the denitrification confirmation means of the first to n predetermined positions including at least the upstream side of each of the first to n predetermined positions along the flow direction of the nitrogen-containing water First gas supply amount control means for controlling the supply amount of gas by the aeration means in each section to be performed;
The other reactions other than the reaction tank provided with the denitrification confirmation means based on the respective dissolved oxygen amounts measured at the respective predetermined positions of the first to na of the reaction tank provided with the denitrification confirmation means A means for setting a dissolved oxygen target concentration at each of the predetermined positions of the first to na of the tank;
The first of the reaction vessels is determined so that the measured value of the dissolved oxygen at each of the predetermined positions of the first to na of the reaction vessels other than the reaction vessel provided with the denitrification confirmation means respectively matches the target concentration. Second gas supply amount control means for controlling the supply amount of gas by the aeration means in each section in which control of the aeration means is performed due to the denitrification confirmation means at a predetermined position of to n;
And the like.

The control method according to the present invention is as follows.
(7) In the flow direction of the nitrogen-containing water in any one reaction vessel among a plurality of reaction vessels of the same type connected in parallel and controlled such that the flow rate of the inflowing nitrogen-containing water is the same An upstream denitrifying section for obtaining the minimum necessary denitrifying nitrogen amount, and a downstream nitrification section for obtaining the finally necessary nitrifying water quality downstream of the upstream denitrifying section along the line; And denitrification confirmation means for confirming whether denitrification is being performed or not for the desired proportion of nitric acid provided at an intermediate position between Ammonia contained in the nitrogen-containing water is nitrified to nitric acid, and each desired ratio of nitric acid is denitrified at each position along the flow direction of the nitrogen-containing water with respect to the nitrogen-containing water in the flow direction Aeration means for supplying gas over substantially the entire area, side by side The same intermediate position as the intermediate position in a section where control of the aeration means is performed due to the denitrification confirmation means excluding the section until the aeration effect is expressed by the aeration means, or the intermediate position Control means for controlling the aeration means used for the aeration means in the case where the apparatus is provided at a predetermined position corresponding to the measurement means for measuring the dissolved oxygen amount of the nitrogen-containing water at the predetermined position There,
The denitrification confirming means along the flow direction of the nitrogen-containing water so that the desired proportion of the nitric acid is denitrified at the halfway position based on the denitrification state confirmed by the denitrification confirming means A first gas supply amount control step of controlling the supply amount of gas by the aeration means in a section where the control of the aeration means caused by the denitrification confirmation means, including at least the upstream side, is performed;
Other than the reaction vessel provided with the denitrification confirming means and based on the respective dissolved oxygen amounts measured at the predetermined positions corresponding to the halfway position of the reaction vessel provided with the denitrification confirming means and the nitrification confirming means Setting a dissolved oxygen target concentration at the predetermined position of the other reaction vessel of
Aeration due to the denitrification confirming means of the reaction vessel such that the measured value of the dissolved oxygen at the predetermined position of the reaction vessel other than the reaction vessel provided with the denitrification confirming means matches the target concentration A second gas supply amount control step of controlling a supply amount of gas by the aeration means in a section where control of the means is performed;
It is characterized by including.

(8) In the flow direction of the nitrogen-containing water in any one reaction vessel among a plurality of reaction vessels of the same type connected in parallel and controlled such that the flow rate of the inflowing nitrogen-containing water is the same An upstream denitrifying section for obtaining the minimum necessary denitrifying nitrogen amount, and a downstream nitrification section for obtaining the finally necessary nitrifying water quality downstream of the upstream denitrifying section along the line; The denitrification state as to whether or not each desired proportion of nitric acid is denitrified provided at each predetermined position of the first to n (n is a natural number of 2 or more) located in any one of Ammonia contained in the nitrogen-containing water is nitrated to nitric acid according to the flow of nitrogen-containing water in each reaction tank, and nitric acid is added at each position along the flow direction of the nitrogen-containing water in each reaction vessel. To the nitrogen-containing water so that each desired fraction of And means for supplying gas over substantially the entire flow direction, and means for confirming denitrification at the first to nth predetermined positions except for a section until the aeration effect of the means for aeration is expressed. And the first to n predetermined positions corresponding to the first to n predetermined positions are the same position or different positions as the first to n predetermined positions in each section in which the control of the aeration means caused by the Control of the aeration means used for the aeration means in the case where the oxygen concentration measuring means is provided to measure the dissolved oxygen amount of the nitrogen-containing water at each predetermined position of the first to na Method,
Based on the denitrification states confirmed by the denitrification confirmation means at the first to nth predetermined positions, the desired ratio of the nitric acid is denitrified at each of the first to nth predetermined positions, Control of the aeration means caused by the denitrifying confirmation means at the first to n predetermined positions including at least the upstream side of each of the first to n predetermined positions along the flow direction of the nitrogen-containing water A first gas supply amount control step of controlling the supply amount of gas by the aeration means in each section in which
The other reactions other than the reaction tank provided with the denitrification confirmation means based on the respective dissolved oxygen amounts measured at the respective predetermined positions of the first to na of the reaction tank provided with the denitrification confirmation means Setting the dissolved oxygen target concentration at each predetermined position of each of the first to na of the tank;
In the reaction vessels other than the reaction vessel provided with the denitrification confirmation means, the first of the reaction vessels such that the measured value of dissolved oxygen at each predetermined position of the first to na of the reaction vessels matches the target concentration. A second gas supply amount control step of controlling the supply amount of gas by the aeration means in each section in which control of the aeration means is performed due to the denitrification confirmation means at a predetermined position of to n;
It is characterized by including.

Furthermore, the program according to the present invention is as follows.
(9) A flow rate control step of controlling so that the flow rates of nitrogen-containing water flowing into the plurality of reaction vessels of the same type connected in parallel become the same;
In any one reaction vessel of the plurality of reaction vessels, an upstream denitrifying section for obtaining a minimum necessary denitrifying nitrogen amount along the flow direction of the nitrogen-containing water, and the upstream denitrifying section Between the downstream side and the downstream side nitrification zone for obtaining the finally necessary nitrification water quality downstream, the denitrification whether or not the desired proportion of the nitric acid is denitrified at the midway position at the midway position Denitrification check step to check the status of
Based on the denitrification state confirmed in the denitrification confirmation step, at least upstream from the halfway position along the flow direction of the nitrogen-containing water so that the desired ratio of the nitric acid is denitrified at the halfway position based on the denitrification state confirmed A first gas supply amount control step of controlling the supply amount of gas by the aeration means in a section where the control of the aeration means caused by the denitrification confirmation means including the side is performed;
The same position as in the middle of each reaction tank, except for the section until the aeration effect is expressed by the aeration in the aeration step, in which the control of the aeration means caused by the denitrification confirmation means is performed A dissolved oxygen measurement step of measuring the amount of dissolved oxygen at a predetermined position which is a position or a different position and corresponds to the intermediate position;
Based on the measured value of the dissolved oxygen concentration measured at the predetermined position in the reaction tank in which the denitrification state is confirmed, the dissolved oxygen target in the predetermined position of the reaction tank other than the reaction tank in which the denitrification state is confirmed Dissolved oxygen target concentration setting step to set the concentration,
An aeration means caused by the denitrification confirmation means of the reaction vessel such that the measured value of dissolved oxygen at the predetermined position of the other reaction vessel other than the reaction vessel whose denitrification state is confirmed matches the target concentration A second gas supply control step of controlling a supply amount of gas by the aeration means in a section where control is performed;
It is characterized by including.

(10) a flow rate control step of controlling so that the flow rates of nitrogen-containing water flowing into the plurality of reaction vessels of the same type connected in parallel become the same;
In any one reaction vessel of the plurality of reaction vessels, an upstream denitrifying section for obtaining a minimum necessary denitrifying nitrogen amount along the flow direction of the nitrogen-containing water, and the upstream denitrifying section Any one of the first to n (where n is a natural number of 2 or more) predetermined positions between the downstream side and the downstream side nitrification section for obtaining the finally necessary nitrification water quality downstream A denitrification confirmation step of confirming a denitrification state as to whether or not each desired ratio of the nitric acid is denitrified in
Based on the flow direction of the nitrogen-containing water so that each desired ratio of the nitric acid is denitrified at the first to n-th predetermined positions based on the denitrification states confirmed in the denitrification confirmation step. The control of the gas supply amount by the aeration means in each section in which the control of the aeration means caused by the denitrification confirmation means is performed, including at least the upstream side of each of the first to n predetermined positions 1 gas supply control step;
In each reaction tank, the first to the first sections in each section where the control of the aeration means caused by the denitrification confirmation means is performed excluding the section until the aeration effect is expressed by the aeration in the aeration step. a dissolved oxygen measuring step of measuring the amount of dissolved oxygen at each of the predetermined positions 1a to na corresponding to the first to n predetermined positions, respectively at the same position as or different from the predetermined positions of n;
Based on the measurement value of the dissolved oxygen concentration measured at each of the predetermined positions of the first to na in the reaction vessel in which the denitrification state is confirmed, the above-mentioned other reaction vessels other than the reaction vessel in which the denitrification state is confirmed A dissolved oxygen target concentration setting step of setting the dissolved oxygen target concentration at each of the first predetermined positions 1a to 1n;
In the first to n-th reaction vessels, the measurement value of the dissolved oxygen at each predetermined position of the first to na of the reaction vessels other than the reaction vessel in which the denitrifying state is confirmed matches the target concentration. A second gas supply control step of controlling the supply amount of gas by the aeration means in each section in which control of the aeration means caused by the denitrification confirmation means at a predetermined position is performed;
It is characterized by including.

  According to the apparatus and the method for treating nitrogen-containing water of the present invention, in a nitrogen-containing water treatment facility in which a plurality of reaction vessels of the same type are connected in parallel, removal using an ammonia detector or a nitric acid detector Based on the dissolved oxygen amount distribution in the reaction tank in which the aeration means is controlled so that appropriate denitrification is performed by the nitrogen confirmation means, the dissolved oxygen amounts in other reaction vessels other than the reaction tank provided with the denitrification confirmation means Since it controls, in other reaction vessels, the aeration means can be controlled with the same accuracy as the reaction vessel in which the aeration means is controlled by the denitrification confirmation means, and furthermore, an inexpensive DO meter can be used as a detector

FIG. 1A is an overall configuration diagram showing a nitrogen-containing water treatment apparatus in which a plurality of reaction vessels of the present invention are connected in parallel. FIG. 1B is a block diagram showing a nitrogen-containing water treatment apparatus according to a first embodiment including a reaction vessel 2A of any one of a plurality of reaction vessels 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. 3A shows the nitrogen concentrations of NH ₄ -N, NO ₂ -N, and NO ₃ -N and total nitrogen measured along the flow of the treated water in the reaction vessel in the case of one nitrification meter. It is a graph which shows concentration. FIG. 3B shows the nitrogen concentrations of NH ₄ -N, NO ₂ -N, and NO ₃ -N, and total nitrogen measured along the flow of the treated water in the reaction vessel in the cases where there are multiple nitrification meters. It is a graph which shows concentration. FIG. 4A is a flow chart showing a method of treating nitrogen-containing water according to the first embodiment when there is one nitrification meter of the present invention. FIG. 4B is a flowchart showing a method of treating nitrogen-containing water according to the first embodiment when there are a plurality of nitrification meters of the present invention. FIG. 5 is a block diagram showing a nitrogen-containing water treatment apparatus according to a second embodiment of the present invention. FIG. 6 is a block diagram showing a nitrogen-containing water treatment apparatus according to a third embodiment in which there are a plurality of nitric acid meters of the present invention. FIG. 7 is a block diagram showing a nitrogen-containing water treatment apparatus according to a fourth embodiment in the case where there are a plurality of nitric acid meters of the present invention. FIG. 8 is a perspective perspective view showing a reaction vessel according to a fifth embodiment of the present invention. FIG. 9A is a cross-sectional view of the reaction vessel shown in FIG. 8 taken along the line A-A. FIG. 9B is a cross-sectional view taken along the line B-B in the reaction vessel shown in FIG. FIG. 10 is a block diagram showing a nitrogen-containing water treatment apparatus according to a sixth embodiment in which there are a plurality of nitric acid meters of the present invention. FIG. 11A is a configuration diagram showing another modified example of the reaction vessel according to the embodiment of the present invention. FIG. 11B is a block diagram showing another modification of the reaction vessel according to the embodiment of the present invention. FIG. 11C is a configuration diagram showing another modified example of the reaction vessel according to the embodiment of the present invention. FIG. 11D is a timing chart showing the timing of aeration according to the passage of time of the aeration part in the reaction tank shown in FIG. 8C. FIG. 11E is a view showing another modification of the reaction vessel according to the embodiment of the present invention. FIG. 11F is a cross-sectional schematic view of the carrier carrying microorganisms to be suspended in the reaction tank shown in FIG. 11E. 12A is a configuration diagram showing a case where an ammonia meter is installed in the nitrogen-containing water treatment apparatus shown in FIG. FIG. 12B shows each nitrogen of NH ₄ -N, NO ₂ -N, and NO ₃ -N measured along the flow of the treated water in the reaction tank to explain the target nitrification rate and the measured nitrification rate. It is a graph which shows concentration and total nitrogen concentration.

  Hereinafter, embodiments of the present invention will be described 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 by the embodiments described below.

First Embodiment
(Configuration of nitrogen-containing water treatment system)
First, the configuration of a nitrogen-containing water treatment apparatus including a control device according to a first embodiment of the present invention will be described. FIG. 1A is a schematic view showing an outline of a nitrogen-containing water treatment apparatus. As shown in FIG. 1A, in the apparatus for treating nitrogen-containing water according to the present invention, the apparatuses for treating containing nitrogen-containing water reaction tanks (2A, 2B, 2C,...) Of the same type are connected in parallel. The nitrogen-containing water is supplied at the same flow rate by the flow rate adjusting means 61 to each processing apparatus. The flow rate adjusting unit 61 includes a flow meter, a flow rate adjusting valve, and the like. In the present invention, the same type of reaction vessel means a reaction vessel in which the treatment configuration of nitrogen-containing water is the same including the aeration means.

First Embodiment
(Configuration of nitrogen-containing water treatment system: any one reaction tank in a plurality of reaction tanks)
FIG. 1B is a schematic view showing the configuration of a nitrogen-containing water treatment apparatus according to a first embodiment of the present invention. As shown to FIG. 1B, it is a schematic diagram which shows the structure of the reaction tank 2A in any one of several reaction tanks of this invention. As shown in FIG. 1B, the nitrogen-containing water treatment apparatus according to the first embodiment including any one reaction vessel 2A among the plurality of reaction vessels according to the present invention comprises: A reaction tank 2A consisting of aerobic tanks 2a, 2b, 2c, 2d (first to fourth tanks), a solid-liquid separation tank 3, a sludge return path 5, and a control unit 9 are provided. The first sedimentation tank 1 and the solid-liquid separation tank 3 are common to each reaction tank (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 together and separated into solid and liquid.

  Nitrogen-containing raw water (hereinafter, raw water) flows into the first sedimentation tank 1. In the first settling tank 1, the raw water is allowed to flow gently to precipitate relatively small particles of dust and the like.

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

  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 provided in aeration part 6a-6d, respectively. There is. Each of the gas supply amount control units 10a to 10d includes a gas flow rate control valve or the like, and according to a control signal from the control unit 9 as a part of the gas supply amount control means constituting the control device, each aerobic tank 2a The amount of gas supplied from the aeration unit 6a to 6d at 2d to 2d is controlled uniformly or individually. As 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 have a recording medium such as a CPU, a storage medium such as a ROM or a RAM, and a hard disk. In the control unit 9, a predetermined program capable of executing a method of treating and controlling nitrogen-containing water, which will be described later, is stored in the recording medium. The control unit 9 outputs the control signals according to the stored program in response to the confirmation signal such as the measured value data of the nitric acid concentration input as described later, thereby controlling the gas supply amount control units 10a to 10d. Control is performed to control the amount of gas supplied from the aeration units 6a to 6d.

  Further, at a desired position along the flow of the water to be treated in the reaction tank 2A, one nitric acid meter 7 or a plurality of nitric acid meters 7a and 7b are provided at predetermined positions. The nitric acid meters 7, 7a and 7b as the denitrification confirming means are 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 the first embodiment, the nitric acid meter 7, in the case of a plurality, the nitric acid meter 7a as the first nitric acid meter on the most upstream side along the flow direction of the water to be treated is, for example, at about the middle position of the reaction tank 2A. It is installed at the inflow position of a certain aerobic tank 2c. Here, the installation position of the nitric acid meter 7, 7a can be set to a desired position, and it is used for control of the denitrification reaction as described later, from the position where the amount of nitrogen to be removed by the denitrification reaction can be secured. It is desirable that the downstream side be upstream from the position where the nitrification reaction can be sufficiently performed in the reaction vessel 2A. Furthermore, the installation position of the nitric acid meter 7 can be determined based on the position dependency of the reaction vessel 2A with respect to each concentration of total nitrogen concentration, nitrate nitrogen, nitrite nitrogen, and ammonia nitrogen which are measured in advance. . That is, an upstream side denitrifying section 81 for obtaining the minimum necessary amount of denitrifying nitrogen, and a downstream side nitrification section 82 for obtaining the finally necessary nitrification water quality connected downstream of the upstream denitrifying section Between (in the middle position or at least one predetermined position of the first to n). The control unit 9, the gas supply control unit 10, and the nitric acid meter 7 constitute a system for treating nitrogen-containing water.

In the present specification, nitric acid refers to nitric acid (HNO ₃ ), nitrous acid (HNO ₂ ), nitrate nitrogen (NO ₃ -N), nitrite nitrogen (NO ₂ -N), nitrate nitrogen and nitrite It is a concept including concentration with nitrogen, and NOx, which indicate both nitric acid and nitrous acid. Moreover, in the present specification, ammonia is a concept including ammonia and ammonia nitrogen. That is, in the present specification, the nitric acid concentration is any of nitric acid, nitrous acid, nitrate nitrogen, nitrite nitrogen, aggregation of nitrate nitrogen and nitrite nitrogen, and NOx showing both nitrate and nitrite. It may be a concentration, and the ammonia concentration may be any concentration of ammonia (NH ₃ ) and ammoniacal nitrogen (NH ₄ -N).

  Further, even when the plurality of stages 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 meters 7 and 7a are used as the flow of the water to be treated in the reaction tank 2A. It is provided at a desired position along, for example, the inflow position of the aerobic tank 2c, and in the case of a plurality of nitric acid meters, the nitric acid meter 7b is provided at the most downstream part. In addition, the detail regarding the installation position of nitric acid meter 7, 7a, 7b is mentioned later.

  And when there is one nitric acid meter, the nitric acid meter 7 supplies the measured nitric acid concentration value to the control unit 9, and when there are a plurality of nitric acid meters, the nitric acid meters 7a and 7b, as shown in FIG. The measured nitric acid concentration value is supplied to the control unit 9. The control unit 9 to which the measured nitric acid concentration value is supplied supplies a control signal to the gas supply amount control units 10a to 10d, and the gas supply amount by the aeration unit 6a to 6d is calculated based on the nitric acid concentration value. Control. That is, the control unit 9 and the gas supply control units 10a to 10d constitute a gas supply control unit which is a control device.

  The water to be treated that has flowed out of the most downstream aerobic tank 2 d flows into the solid-liquid separation tank 3. In the solid-liquid separation tank 3, the water to be treated is separated into the separated 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. A 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 amount of biomass in the aerobic tank 2a and the downstream aerobic tanks 2b, 2c, 2d can be maintained at a predetermined amount.

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

In the method of treating nitrogen-containing water performed in the aerobic tanks 2a to 2d, first, the water to be treated from the first sedimentation tank 1 shown in FIG. 1B is sequentially sent from the aerobic tank 2a to the aerobic tank 2d. In each of the aerobic tanks 2a to 2d, ammonia nitrogen (NH ₄ -N) in the water to be treated is converted to the following reaction formula (1) by nitrifying bacteria which are aerobic microorganisms in activated sludge under aerobic conditions. As shown in (4) to (3), nitrite (NO ₂ -N) and nitrate (NO ₃ -N) are nitrated (in FIG. 4A, step ST1 and step ST2).

On the other hand, denitrification reaction (anaerobic reaction) occurs due to denitrification bacteria in the region where the amount of oxygen is small or in a region where the amount of oxygen in the water to be treated in the reaction tank 2A is small or in some cases the nitrification tank. Therefore, if a sufficient carbon source is supplied to the region (the denitrification reaction region) in which the denitrification reaction occurs, the denitrification reaction can be sufficiently advanced. As a result, in the reaction tank 2A, a region where partial denitrification reaction is performed is generated. 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. Nitrite can be reduced and decomposed to nitrogen and carbon dioxide to effect nitrogen removal.

Here, in the case where the denitrification reaction and the nitrification reaction proceed in parallel, the inventor of the present invention 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 flow direction of the water to be treated And the total nitrogen concentration obtained by summing them. FIG. 3A shows the nitrogen concentration and total nitrogen concentration of NH ₄ -N, NO ₂ -N, and NO ₃ -N in the case of multiple nitric acid meters, and FIG. It is a graph which shows the result measured by the position of.

As shown in FIG. 3A, from the inflow side of the aerobic tank 2a on the relatively front half side of the reaction tank 2A to the position on the outflow side of the aerobic tank 2b, NO ₂ -N and NO according to the flow of water to be treated _{The 3-} N nitrogen concentration does not increase much and the total nitrogen concentration decreases. This is because in the aerobic tanks 2a and 2b on the upstream side of the reaction tank 2A, the nitrification reaction area and the denitrification reaction area exist, and the nitrification treatment in the nitrification reaction area and the denitrification treatment in the denitrification reaction area proceed simultaneously It is considered that the nitrogen removal rate is improved. The nitrogen concentration of NO ₂ -N and NO ₃ -N is increased from the inflow side of the aerobic tank 2c, which is the second half of the reaction tank 2A, to the position of the outflow side of the aerobic tank 2d. That is, the present inventor considered that the denitrification reaction was continuously advancing and the nitrification reaction was rapidly advancing in the aerobic tanks 2c and 2d on the downstream side of the reaction tank 2A. Therefore, the inventor first places 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 of the nitric acid meter 7 based on the nitric acid concentration at this position. It was recalled that if the amount is controlled approximately uniformly or individually, both denitrification reaction and nitrification reaction occurring upstream of the nitric acid meter 7 can be controlled.

Specifically, as the water to be treated flows down the reaction tank 2A, the ammonia (NH ₄ ) contained in the water to be treated is gradually added to the nitric acid (NO 2 (NO) by the aeration units 6a to 6d. By supplying a gas to the water to be treated in the reaction tank 2A substantially throughout the flow direction so as to be nitrified to _2- N) and nitrate nitrogen (NO ₃ -N)), It has been 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 can be denitrified. As a result, the inventor places the nitric acid meter 7 at a desired position, and at least from the aeration unit 6 on the upstream side of the nitric acid meter 7 so that the measurement value measured by the nitric acid meter 7 falls within the predetermined range. It has been found that the denitrification reaction and the nitrification reaction upstream of the nitric acid meter 7 can be controlled by uniformly or separately controlling the gas supply amount.

  Therefore, in the present invention, first, the control unit 9 monitors the measurement of the nitric acid concentration by the nitric acid meter 7 or the nitric acid meters 7a and 7b installed on the inflow side of the aerobic tank 2c, and the flow direction of the water to be treated And control at least the gas supply amount control units 10a and 10b on the upstream side of the nitric acid meter 7 and 7a. Further, in the present invention, the gas supply amount in the reaction tank 2A, that is, the gas supply amount in each of the aerobic tanks 2a to 2d is adjusted by the gas supply amount control units 10a to 10d. In this case, in consideration of controlling the denitrification reaction in the reaction tank 2A, the nitric acid meter 7a on the most upstream side of the nitric acid meter 7 or the nitric acid meter 7a, 7b is a region where the denitrification reaction and the nitrification reaction coexist. Position at the position where control of denitrification reaction is desired, for example, in the vicinity of the most downstream side of the region in reaction tank 2A where denitrification reaction needs to be advanced while suppressing the generation of nitric acid due to nitrification reaction. desirable.

Therefore, in the first embodiment, it is desirable to install the nitric acid meter 7 or the nitric acid meter 7a on the inflow side of the aerobic tank 2c. Then, the control unit 9 controls the flow of the water to be treated so that the nitric acid concentration of the total of NO ₂ -N and NO ₃ -N measured by the nitric acid meter 7 or the nitric acid meter 7a falls within a predetermined target range. The nitric acid meter 7 or at least the gas supply control units 10a and 10b upstream of the nitric acid meter 7a are controlled along the direction. Note that the control unit 9 supplies control signals to the gas supply amount control units 10c and 10d as necessary. As a result, the control unit 9 controls the amount of gas supplied to each of the aerobic tanks 2a and 2b, and further to the aerobic tanks 2c and 2d individually or substantially uniformly. Then, when it is not possible to confirm denitrification of a desired ratio to nitric acid generated by nitrification reaction by nitric acid meter 7 or nitric acid meter 7a, nitric acid meter 7 or nitric acid meter 7a along the flow direction of the water to be treated The amount of gas supplied by at least the aeration section 6a, 6b on the upstream side is controlled to increase or decrease individually or uniformly. Then, by controlling the gas supply amount by the control unit 9, the denitrification reaction is allowed to proceed while suppressing the nitrification reaction in the treated water upstream of the nitric acid meter 7 or the nitric acid meter 7a in the reaction tank 2A. Can. On the downstream side of the nitric acid meter 7 or the nitric acid meter 7a, 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. The treated water has more aerobic conditions and the nitrification reaction proceeds rapidly, and ammonia (NH ₄ ) decreases rapidly, and nitric acid (nitrite nitrogen (NO ₂ -N) and nitrate nitrogen (NO ₃₎ The concentration of -N) increases rapidly. In the control of the gas supply amount, aeration may be performed continuously as described later, or may be performed intermittently including stop control of aeration with the gas supply amount set to zero.

Specifically, when there is one nitric acid meter, 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 2c (in FIG. 4A, step ST3). . The nitric acid meter 7 supplies the measured value of the nitric acid concentration to the control unit 9. Control unit 9 determines whether or not the supplied nitric acid concentration is within a predetermined range, that is, whether or not it is within a predetermined target range (setting target range) such as 5.0 mg / L or less. (In FIG. 4A, step ST4).

  Here, according to the findings of the present inventor, when the nitric acid concentration in the reaction tank 2A exceeds 5.0 mg / L, the nitrification proceeds rapidly, and even if the amount of air is reduced, the inside of the reaction tank 2A The target setting range is preferably 5.0 mg / L or less, because it becomes difficult to control the situation. When the measured value of the supplied nitric acid concentration is within the set target range (step ST4 in FIG. 4A: Yes), the control unit 9 continues monitoring the nitric acid concentration by the nitric acid meter 7 (FIG. 4A). Middle, step ST3). As to this setting target range, an optimum setting target range is set for each reaction tank according to the design of the shape, dimensions, etc. of the reaction tank 2A.

  On the other hand, the controller 9 determines that the measured value of the nitric acid concentration supplied from the nitric acid meter 7 is less than the set target range, that is, less than the lower limit of the set target range (step ST4 in FIG. 4A: No), A control signal is supplied to the supply amount control units 10a to 10d to perform control to at least increase the gas supply amount from the aeration units 6a and 6b so as to increase the nitric acid concentration in at least the aerobic tanks 2a and 2b In FIG. 4A, step ST5). At this time, in the aerobic tanks 2c and 2d, control may be performed to increase the amount of gas supplied by the aeration units 6c and 6d similarly to the aeration units 6a and 6b, or may not be controlled.

  On the other hand, when the value of the nitric acid concentration supplied from the nitric acid meter 7 exceeds the set target range, that is, the upper limit of the set target range is exceeded, the control unit 9 also measures the nitric acid concentration out of the set target range. (Step ST4 in FIG. 4A: No), and at least the scattering is performed so as to reduce the nitric acid concentration in at least the aerobic tanks 2a and 2b by supplying a control signal to the gas supply amount control units 10a to 10d. Control is performed to reduce the amount of gas supplied by the air units 6a and 6b (step ST5 in FIG. 4A). At this time, in the aerobic tanks 2c and 2d, the control unit 9 performs control not to change the amount of gas supplied by the aeration units 6c and 6d even if the control is performed to reduce the gas supply amount similarly to the aeration units 6a and 6b. You may go.

  That is, in the control of the aeration units 6a to 6d described above, the gas supply amount from the aeration units 6a to 6d is uniformly increased or decreased, or the gas supply amount from the aeration units 6a and 6b is increased or decreased. It is possible to maintain the amount of gas supplied from the air portion 6c, 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 on the upstream side of the aerobic tank 2b, at least the gas supply amount controller 10a controls the control unit 9 from the aeration unit 6a. Control the gas supply of the On the other hand, when the nitric acid meter 7 is installed downstream of the aerobic tank 2c or upstream of the aerobic tank 2d, the controller 9 at least controls the gas supply units 10a to 10c to supply the aeration units 6a to 6c. Control each gas supply from 6c. In addition, in control of these gas supply amounts, the control part 9 may perform independent control for each gas supply amount control part 10a-10d with respect to each aeration part 6a-6d, The same control may be performed, and a plurality of aeration sections may be appropriately selected and grouped in the aeration sections 6a, 6b, 6c, and 6d, and control may be performed independently for each group.

  In this manner, the control unit 9 supplies control signals to the respective gas supply amount control units 10a to 10d, and controls the gas supply amounts in the respective aeration units 6a to 6d, whereby the aerobic tanks 2a and 2b are provided. The denitrification reaction and the nitrification reaction can be made to coexist appropriately in the interior to control the generation of the denitrification reaction inside the reaction tank 2A. In addition, since the control unit 9 controls the gas supply amount optimally, the gas supply amount by the aeration units 6a to 6d can be controlled to a necessary and sufficient amount, and the power consumption of the blower 8 is reduced. It is also possible to reduce the power consumption in the nitrogen-containing water treatment.

  When there are a plurality of nitric acid meters, the control unit 9 determines that the measured values at at least one of the measured values of nitric acid concentration at the respective installation positions by the supplied nitric acid meters 7a and 7b are out of the set target range. If it does (in FIG. 4B, step ST4: No), it will transfer to step ST5. In step ST5, the control unit 9 supplies a control signal to the gas supply amount control units 10a to 10d to increase the nitric acid concentration in the aerobic tank 2a to 2d when the nitric acid concentration is less than the lower limit of the target setting range. The aeration part is controlled to increase the gas supply amount by the aeration parts 6a to 6d, or to decrease the nitric acid concentration of the aerobic tank 2a to 2d when the nitric acid concentration is larger than the upper limit of the target setting range. Control is performed to reduce the gas supply amount by 6a to 6d.

  That is, in the control of the aeration units 6a to 6d described above, the gas supply amount from the aeration units 6a to 6d is uniformly increased or decreased, or the gas supply amount from the aeration units 6a and 6b is increased or decreased. It is possible to maintain the amount of gas supplied from the air portion 6c, 6d constant. In addition, according to each installation position of nitric acid meter 7a, 7b, the aeration part 6a-6d which needs to perform increase / decrease control is selected. Specifically, when the nitric acid meter 7a is installed on the downstream side of the aerobic tank 2a or on the upstream side of the aerobic tank 2b, at least the gas supply amount control section 10a controls the controller 9 from the aeration section 6a. Control the gas supply of the On the other hand, when the nitric acid meter 7a is installed downstream of the aerobic tank 2c or upstream of the aerobic tank 2d, the controller 9 at least controls the gas supply units 10a to 10c to supply the aeration units 6a to 6c. Control each gas supply from 6c. The same applies to the control based on the nitric acid meter 7b, and controls the aeration part downstream of at least the nitric acid meter 7a and upstream of the nitric acid meter 7b among the aeration units 6a to 6d. Do. Furthermore, in the control of these gas supply amounts, the control unit 9 may perform independent control for each of the gas supply amount control units 10a to 10d with respect to each of the aeration units 6a to 6d. The same control may be performed, and a plurality of aeration sections may be appropriately selected and grouped in the aeration sections 6a, 6b, 6c, and 6d, and control may be performed independently for each group.

Specifically, the control unit 9 sets in advance a nitric acid concentration (hereinafter, nitric acid concentration) of the total of NO ₂ -N and NO ₃ -N measured by the nitric acid meter 7a is, for example, 5.0 mg / L or less in advance. Control signals are supplied to the gas supply amount control units 10a to 10d so as to be within the target setting range, and the gas supply amounts by the respective aeration units 6a to 6d in the respective aerobic tanks 2a to 2d are controlled.

  Further, the setting target range of the nitric acid concentration to be controlled is the case where nitrification is promoted in the reaction tank 2A and the nitrification is suppressed whenever the hydraulic retention time (HRT) from the nitric acid meter 7a becomes downstream for one hour, for example. In each case, it is set to increase by a predetermined increase amount.

  Specifically, when promoting nitrification in the reaction tank 2A, the setting target range of the nitric acid concentration to be controlled is, for example, 5.0 mg / hour each time the hydraulic residence time from the nitric acid meter 7a is on the downstream side. Increase by a predetermined increase amount of L or more. That is, when the nitric acid meter 7b is installed on the downstream side where the hydraulic residence time is 1 hour from the nitric acid meter 7a, the set target range at the installation position of the nitric acid meter 7b is set to a predetermined range of 10.0 mg / L or more, for example. The target value of the setting position at the installation position of the nitric acid meter 7a is increased by 5.0 mg / L or more.

  On the other hand, when suppressing nitrification in the reaction tank 2A, the setting target range of the nitric acid concentration to be controlled is, for example, 3.0 mg / L or less every time the hydraulic residence time from the nitric acid meter 7a becomes downstream for 1 hour. Increase by a predetermined amount of increase. That is, when the nitric acid meter 7b is installed on the downstream side where the hydraulic residence time is 1 hour from the nitric acid meter 7a, the set target range at the installation position of the nitric acid meter 7b is set to a predetermined value of, for example, 8.0 mg / L or less. The value is increased by 3.0 mg / L or less from the set target range at the installation position of the nitric acid meter 7a. And control part 9 controls the gas supply quantity by aeration part 6a-6d so that the measurement value by each nitric acid meter 7a, 7b becomes in the setting target range mentioned above in each nitric acid meter 7a, 7b. Do.

  In particular, when there are a plurality of nitric acid meters, denitrification reaction and nitrification reaction can be made to coexist in the aerobic tanks 2a and 2b according to the measurement value of the nitric acid meter 7a, and can be appropriately controlled. Depending on the measured value, denitrification reaction and nitrification reaction can be made to coexist in the aerobic tank 2c, 2c and appropriately controlled. This makes it possible to control the denitrification reaction inside the reaction tank 2A together with the nitrification reaction. In addition, since the control unit 9 controls the gas supply amount optimally, the gas supply amount by the aeration units 6a to 6d can be controlled to a necessary and sufficient amount, and the power consumption of the blower 8 is reduced. It is also possible to reduce the power consumption in the nitrogen-containing water treatment.

According to the first embodiment of the present invention described above, in the case of one nitric acid meter, the reaction tank 2A
In a plurality of aerobic tanks 2a to 2d constituting the reaction vessel, the desired position along the flow direction of the water to be treated in the reaction tank 2A, for example, the nitric acid at the inflow part side of the aerobic tank 2c Based on the measurement of the nitric acid concentration by the nitric acid meter 7, a total of 7 are provided, and at least the aeration sections 6a and 6b, and if necessary, the aeration sections 6a to 6d, so that the nitric acid concentration falls within the predetermined range. The gas supply amount in the gas tank 2a-2d is controlled. Thereby, the denitrification reaction performed mainly in the aerobic tank 2a, 2b on the relatively front half side of the reaction tank 2A can be controlled together with the nitrification reaction, and the nitrogen removal rate can be improved, and An appropriate amount of oxygen can be supplied to the reaction tank 2A according to the organic substance load and the nitrogen load of water.

  In addition, as shown in FIG. 1A, when there is another reaction tank 2B, 2C... Of the same shape as the reaction tank 2A, and there is inflow of nitrogen-containing water under the same conditions and return sludge return, the other The reaction tank also controls the gas supply amount under the same conditions as the reaction tank 2A, and if the appropriate amount of oxygen is supplied, the same accuracy as the above-mentioned reaction tank 2A (any one reaction tank in a plurality of reaction tanks) Can control denitrification and nitrification.

  Therefore, in the present invention, the DO meter 88 is provided corresponding to the nitric acid meter 7 in any one reaction tank 2A in a plurality of reaction tanks. In this DO meter, since the change in the amount of dissolved oxygen resulting from the control of the aeration amount from the aeration means is measured based on the measurement value of the nitric acid meter 7, the DO meter corresponding to the nitric acid meter is It may be provided at a predetermined position in a section where the control of the aeration means is performed based on the measurement value of the nitric acid meter 7. However, the amount of dissolved oxygen hardly changes in the section until the aeration effect by the aeration means near the inlet of the reaction tank appears. Therefore, those sections 83 that cause changes less than the measurement limit of the DO meter used do not make sense of providing the DO meter and are naturally excluded.

In the reaction vessels (2B, 2C, ...) other than any one reaction vessel 2A in the plurality of reaction vessels, a DO meter is provided at the same predetermined position as the DO meter 88 corresponding to each nitric acid meter in the reaction vessel 2A. It is provided.
On the other hand, the dissolved oxygen amount measured in the DO meter 88 of any one reaction tank 2A in the plurality of reaction tanks is sent to the control unit 9, and the DO meter in each reaction tank (2B, 2C,...) It is set to the target value of 88. Then, in each reaction tank (2B, 2C, ...), the diffusion means of the reaction tank is controlled so that the dissolved oxygen amount measured by the DO meter 88 of each reaction tank matches the set target. .
That is, when the measured value of the DO meter 88 of the reaction tank 2B does not match the target value, the diffusion means of the reaction tank 2B corresponding to the diffusion means 6a to 6d controlled by the denitrification confirmation means of the reaction tank 2A. The aeration amount is controlled by 6a to 6d.

  On the other hand, when there are a plurality of nitric acid meters, a plurality of nitric acid meters 7a and 7b are installed in the reaction tank 2A, and the most upstream nitric acid meter 7a of these nitric acid meters 7a and 7b is a denitrification zone in the reaction tank 2A. It is installed at a desired position to be controlled, and based on the measurement of nitric acid concentration by this nitric acid meter 7a, 7b, the gas supply amount in the aerobic tanks 2a to 2d is controlled so that the nitric acid concentration becomes within the setting target range. There is. Thereby, it is possible to control the denitrification reaction mainly performed in the aerobic tanks 2a and 2b which is the first half of the reaction tank 2A, and it is possible to improve the nitrogen removal rate, and An appropriate amount of oxygen can be supplied to the reaction tank 2A according to the nitrogen load. In addition, denitrification in the reaction tank 2A is achieved by making the upper limit of the target setting value of the nitric acid concentration by the plurality of nitric acid meters 7a and 7b different in the case of promoting nitrification in the reaction tank 2A and the case of suppressing nitrification. It is possible to control the reaction and the nitrification reaction more appropriately.

In the present invention, DO meters 88 and 89 are provided corresponding to the nitric acid meters 7a and 7b in the reaction tank 2A. In this DO meter, the change in the amount of dissolved oxygen resulting from the control of the aeration amount from the aeration means is measured based on the measurement values of the nitric acid meters 7a and 7b. Therefore, the DO meter corresponding to the nitric acid meter May be provided at a predetermined position in the section (84, 85) where the control of the aeration means is performed based on the measurement values of the nitric acid meters 7a, 7b. However, the amount of dissolved oxygen hardly changes in the section 83 until the aeration effect by the aeration means near the inlet of the reaction tank appears. Therefore, those sections 83 that cause changes less than the measurement limit of the DO meter used do not make sense of providing the DO meter and are naturally excluded.
In reaction vessels (2B, 2C,...) Other than any one reaction vessel 2A in the plurality of reaction vessels, DO at the same predetermined position as DO meters 88, 89 corresponding to the respective nitric acid meters in the reaction vessel 2A. A total is provided.
On the other hand, the dissolved oxygen amount measured in the DO totals 88 and 89 of the reaction tank 2A is sent to the control unit 9 and is made the target value of the DO totals 88 and 89 in each reaction tank (2B, 2C,...). It is set. And, in each reaction tank (2B, 2C, ...), the diffusion means of the reaction tank controls so that the dissolved oxygen amount measured by DO meter 88, 89 of each reaction tank matches the set target. Be done.
That is, when the measured value of the DO meter 88 of the reaction tank 2B does not match the target value, the dispersion of the reaction tank 2B corresponding to the diffusion means 6a, 6b controlled by the measured value of the nitric acid meter 7a of the reaction tank 2A. Aeration means controlled by the measurement value of the nitric acid meter 7b of the reaction tank 2A when the aeration amount is controlled by the air means 6a, 6b and the measured value of the DO meter 89 of the reaction tank 2B does not match the target value. The aeration amount is controlled by the aeration means 6c, 6d of the reaction tank 2B corresponding to 6c, 6d.

(Modification 1 of the first embodiment)
Moreover, in the first embodiment, the reaction tank 2A is configured of four aerobic tanks 2a to 2d, but it is also possible to use this reaction tank 2A as a single tank in which the flow of the water to be treated occurs. is there. FIG. 2B is a plan view of a case where the reaction vessel 2A is configured as a single vessel, as a first modification of the first embodiment. As shown in FIG. 2B, the aeration means may be constituted by a single aeration part 6 instead of the plurality of aeration parts 6a to 6d. Also in this case, the nitric acid meter 7 or the nitric acid meter 7a on the most upstream side of the nitric acid meters 7a and 7b is the most downstream side of the area where the denitrification reaction needs to be controlled along the flow direction of the water to be treated. It is provided at a desired position, but in the case of one nitric acid meter, it is provided at a substantially middle position along the flow direction of the water to be treated in the reaction vessel 2A here. Even when the aeration means is constituted by the single aeration unit 6, the gas supply amount may be controlled for each gas supply portion in the reaction tank 2A in the aeration unit 6 . Further, even when the reaction vessel 2A is a single vessel, the aeration means may be constituted of a plurality of aeration parts as in the first embodiment described above. Further, even when the reaction vessel 2A is a single vessel and the aeration means is composed of a plurality of aeration units, the plurality of aeration units may be controlled independently of each other or may be controlled in the same manner. .

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

  As shown in FIG. 5, in the apparatus for treating nitrogen-containing water according to the second embodiment, unlike the first embodiment, the reaction tank 2A is not a multistage aerobic tank but a single aerobic tank. It consists of a nitrification denitrification reaction tank. In addition, a 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. In this case, nitric acid meters 7a and 7b are provided at desired two or more desired positions along the flow direction of the water to be treated in the reaction tank 2A. The nitric acid meter 7, 7a, 7b measures the nitric acid concentration at their predetermined position and supplies the measurement result to the control unit 9. The control unit 9 controls the gas supply amount (aeration amount) of the aeration units 6a, 6b, 6c, 6d at least upstream of the respective nitric acid meters based on the supplied nitric acid concentrations. The control unit 9 can also control the aeration units 6a to 6d so that the gas supply amount becomes uniform across the reaction tank 2A, and the aeration units 6a and 6b and the aeration unit 6c , 6d can also be controlled individually.

  Moreover, the anaerobic tank 12 is provided in the front | former stage along the flow direction of the to-be-processed water with respect to 2 A of reaction tanks. The anaerobic tank 12 is a tank into which the to-be-processed water which is nitrogen containing water flows in via the sedimentation tank 1 initially. In the anaerobic tank 12, the stirring part 12b which can be rotated by the external motor 12a is provided, and the activated sludge in the anaerobic tank 12 is stirred by this stirring part 12b. In addition, depending on the configuration of the sewage treatment plant, the first settling place 1 may not be provided, and 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 under an anaerobic environment. And in the anaerobic tank 12, while the organic substance contained in to-be-processed water is taken in to activated sludge under anaerobic conditions, the phosphorus contained in activated sludge is discharge | released to raw water.

  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 amount of biomass in the anaerobic tank 12 and the reaction tank 2A on the downstream side can be maintained at a predetermined amount. The remaining portion of the activated sludge 4b generated in the solid-liquid separation tank 3 is discharged to the outside as excess sludge. The other configuration is the same as that of the first embodiment, so the description will be omitted.

  In the second embodiment, a nitric acid meter 7 or a nitric acid meter 7a or 7b for supplying the measured nitric acid concentration to the control unit 9 is installed at a desired position of the single reaction vessel 2A. Thus, the same effect as that of the first embodiment can be obtained.

Third Embodiment
Next, the configuration of a nitrogen-containing water treatment apparatus according to a third embodiment of the present invention will be described. FIG. 6 is a schematic view showing the configuration of the nitrogen-containing water treatment apparatus according to the second embodiment. As shown in FIG. 6, the nitrogen-containing water treatment apparatus according to the third embodiment of the present invention comprises a first settling tank 1, a plurality of stages of aerobic tanks 2a, 2b, 2c, 2d (first tank to A reaction tank 2A consisting of four tanks, a solid-liquid separation tank 3, a sludge return path 5, and a control unit 9 are provided.

  In the third embodiment, a plurality of nitric acid meters 7a, 7b, 7c, 7d are provided along the flow direction of the water to be treated in the reaction tank 2A. These nitric acid meters 7a to 7d are nitric acid concentration measuring means for measuring the nitric acid concentration of the water to be treated. At least one of the nitric acid meters 7a to 7d is at approximately one middle position along the flow of the water to be treated in the reaction tank 2A, that is, at an intermediate position in the aerobic tanks 2a to 2d. It is provided on the inflow side of the aerobic tank 2c downstream of 2b. Further, even when the plurality of stages of aerobic tanks 2a to 2d constituting the reaction tank 2A are arranged in a folded manner as shown in FIG. 2A, at least one nitric acid meter 7a of the sulfuric acid meters 7a to 7d Is provided at the inflow position of the aerobic tank 2c, which is a substantially middle position along the flow of the water to be treated in the reaction tank 2A. In addition, as such at least one nitric acid meter, it is preferable to adopt the nitric acid meter 7a provided on the most upstream side among the plurality of nitric acid meters 7a to 7d, but the nitric acid meter 7b, 7c provided in the middle, the most A nitric acid meter 7d provided downstream may be employed.

  Then, as shown in FIG. 6, the nitric acid meters 7 a to 7 d supply the measured value of the nitric acid concentration to the control unit 9. The control unit 9 to which the measured nitric acid concentration value is supplied supplies a control signal to the gas supply amount control units 10a to 10d, and the gas supply amount by the aeration unit 6a to 6d is calculated based on the nitric acid concentration value. Control. That is, the control unit 9 and the gas supply control units 10a to 10d constitute a gas supply control unit. The other configuration is the same as that of the first embodiment, so the description will be omitted.

(Gas supply control in treatment method of nitrogen-containing water)
Next, control of the gas supply amount in the method of treating nitrogen-containing water performed in the aerobic tanks 2a to 2d will be described with reference to FIG. 4B as appropriate.

  That is, as in the first embodiment, steps ST1 and ST2 are executed. Thereafter, the nitric acid meters 7a to 7d measure the nitric acid concentration at each installation position (in FIG. 4B, step ST3). The nitric acid meters 7a to 7d supply the measured value of the nitric acid concentration at each installation position to the control unit 9. The control unit 9 determines whether or not the measured values of the nitric acid concentration supplied by the nitric acid meter 7a to 7d are within the set target range previously set for each installation position of the nitric acid meter 7a to 7d. (In FIG. 4B, step ST4).

  When all the measured values of the nitric acid concentration by the nitric acid meter 7a to 7d supplied to the control unit 9 are all within the preset target range (step ST4 in FIG. 4B: Yes), the control unit 9 is Continue monitoring the nitric acid concentration by the nitric acid meter 7a to 7d (step ST3 in FIG. 4B).

  On the other hand, the control unit 9 determines that the measurement value at at least one of the measurement values of the nitric acid concentration at each of the installation positions (first to fourth predetermined positions) by the supplied nitric acid meter 7a to 7d is a set target range. If it judges that it has remove | deviated (step ST4: No in FIG. 4B), it will transfer to step ST5. In step ST5, the control unit 9 supplies a control signal to the gas supply amount control units 10a to 10d to increase the nitric acid concentration of the aerobic tank 2a to 2d when the nitric acid concentration is less than the lower limit of the set target range. , The control to increase the gas supply amount by the aeration units 6a to 6d, or the aeration unit 6a so as to reduce the nitric acid concentration of the aerobic tank 2a to 2d when the nitric acid concentration is larger than the upper limit of the setting target range. Control to decrease the gas supply amount by ~ 6d is performed.

  Specifically, the control unit 9 first causes the nitric acid concentration measured by the nitric acid meter 7a installed at the first predetermined position to fall within the set target range in advance, for example, 5.0 mg / L or less. The control signal is supplied to the gas supply amount control units 10a to 10d. As a result, the gas supply amount of the aeration units 6a and 6b on the upstream side of at least the first predetermined position is controlled, and the denitrification reaction and the nitrification reaction in each of the aerobic tanks 2a to 2d are controlled.

  In addition, the setting target range of the nitric acid concentration to be controlled is each when promoting nitrification and suppressing nitrification in the reaction tank 2A each time the hydraulic residence time on the downstream side from the nitric acid meter 7a is 1 hour downstream. , Is set to increase by a predetermined increase amount.

  Specifically, when promoting nitrification in the reaction tank 2A, the setting target range of the nitric acid concentration to be controlled is, for example, 5.0 mg / hour each time the hydraulic residence time from the nitric acid meter 7a is on the downstream side. Increase by a predetermined increase amount of L or more. That is, when the nitric acid meter 7b is installed at the second predetermined position on the downstream side where the hydraulic residence time is 1 hour from the nitric acid meter 7a, the upper limit of the setting target range at the second predetermined position of the nitric acid meter 7b is For example, as a predetermined value of 10.0 mg / L or more, the value is increased by 5.0 mg / L or more from the upper limit of the setting target range at the installation position of the nitric acid meter 7a.

  On the contrary, when suppressing nitrification in the reaction tank 2A, the upper limit of the setting target range of the nitric acid concentration to be controlled is, for example, 3.0 mg / hour each time the hydraulic residence time from the nitric acid meter 7a is on the downstream side. Increase by a predetermined increment below L. That is, when the nitric acid meter 7b is installed on the downstream side where the hydraulic residence time is 1 hour from the nitric acid meter 7a, the upper limit of the setting target range at the installation position of the nitric acid meter 7b is, for example, a predetermined value of 8.0 mg / L or less The value is increased by 3.0 mg / L or less from the upper limit of the setting target range at the installation position of the nitric acid meter 7a.

  Then, the control unit 9 controls the gas supply amount from a part of the aeration unit 6c between at least the first predetermined position and the second predetermined position.

  Furthermore, when the nitric acid meter 7c is installed at the third predetermined position on the downstream side where the hydraulic residence time is 1 hour from the nitric acid meter 7b, the setting target range at the third predetermined position of the nitric acid meter 7c is nitrification In the case of acceleration, it is increased by a predetermined increase amount of, for example, 5.0 mg / L or more from the setting target range of the nitric acid meter 7 b, for example, to a predetermined value of at least 15.0 mg / L or more. On the contrary, the setting target range at the installation position of the nitric acid meter 7c in the case of the nitrification suppression is increased from the setting target range of the nitric acid meter 7b by a predetermined increment of 3.0 mg / L or less, for example, at most 11.0 mg / Let L be a predetermined value less than or equal to L. Then, the control unit 9 controls the gas supply amount from a part of the aeration unit 6c between at least the second predetermined position and the third predetermined position.

  Similarly, in the nitric acid meter 7d, when the nitric acid meter 7c is installed at the fourth predetermined position on the downstream side where the hydraulic residence time is 1 hour, the setting target range at the fourth predetermined position of the nitric acid meter 7d In the case of promotion of nitrification, it is increased by a predetermined increment of, for example, 5.0 mg / L or more from the setting target range of the nitric acid meter 7c, and becomes, for example, a predetermined value of at least 20.0 mg / L. On the other hand, the setting target range at the installation position of the nitric acid meter 7d in the case of nitrification suppression is increased by a predetermined increment of 3.0 mg / L or less from the setting target range of the nitric acid meter 7c, for example, at most 14.0 mg It becomes a predetermined value less than / L. Then, the control unit 9 controls the gas supply amount from the aeration unit 6 d between at least the third predetermined position and the fourth predetermined position.

  As described above, the control unit 9 supplies the gas by the aeration units 6a to 6d so that the measured values by the nitric acid meters 7a to 7d fall within the above-mentioned set target ranges in the nitric acid meters 7a to 7d. Control the quantity. As described above, the control unit 9 supplies control signals to the respective gas supply amount control units 10a to 10d, and controls the gas supply amounts by the respective aeration units 6a to 6d, whereby the inside of the aerobic tanks 2a and 2b is provided. In this case, the denitrification reaction can be made to coexist while suppressing the nitrification reaction, and the denitrification reaction can be appropriately controlled, and the denitrification reaction in the entire region in the reaction tank 2A can be controlled together with the nitrification reaction. In addition, when denitrification of a desired ratio to the nitric acid generated by the nitrification reaction can not be confirmed by the nitric acid meter 7a, the aeration part 6a, 6b at least upstream of the nitric acid meter 7a along the flow direction of the water to be treated Increase or decrease the gas supply amount individually or uniformly. Similarly, when denitrification of a desired ratio to nitric acid can not be confirmed by the nitric acid meter 7b, 7c, 7d, at least the nitric acid meter 7a, 7b, 7c upstream of at least each nitric acid meter 7b, 7c, 7d. The amount of gas supplied by the aeration units 6c and 6d is controlled to increase or decrease individually or uniformly. By controlling the gas supply amount by the control unit 9 in this manner, it is possible to allow the denitrification reaction to proceed while suppressing the nitrification reaction in the water to be treated on the upstream side of the nitric acid meter 7a in the reaction tank 2A. The denitrification reaction and the nitrification reaction can also be controlled for the water to be treated downstream of the nitric acid meter 7a. In addition, since the control unit 9 controls the gas supply amount optimally, the gas supply amount by the aeration units 6a to 6d can be controlled to a necessary and sufficient amount, and the power consumption of the blower 8 is reduced. It is also possible to reduce the power consumption in the nitrogen-containing water treatment.

  According to the third embodiment of the present invention, by installing the nitric acid meters 7a to 7d in the reaction tank 2A, the same effect as that of the first embodiment can be obtained, and the reaction tank 2A can be obtained. Nitric acid meters 7a to 7d for measuring the nitric acid concentration at the first to fourth predetermined positions, which are more than four in the first embodiment, are installed, and one of these nitric acid meters 7a to 7d is installed. The most upstream nitric acid meter 7a is installed in the reaction tank 2A on the inflow side of the aerobic tank 2c which is a desired position for controlling denitrification reaction, and further, the measurement of nitric acid concentration by these nitric acid meters 7a to 7d The amount of gas supplied to the aerobic tanks 2a to 2d is controlled so that the nitric acid concentration falls within the set target range. As a result, the denitrifying reaction mainly performed in the reaction tank 2A can be controlled more finely, and the nitrogen removal rate can be improved, and the reaction tank 2A can be adjusted according to the organic substance load and nitrogen load of the water to be treated. An appropriate amount of oxygen can be supplied. Further, the upper limit of the target setting range of the nitric acid concentration by the plurality of nitric acid meters 7a to 7d is made different between the case where nitrification is promoted and the case where nitrification is suppressed while appropriately generating denitrification reaction in reaction tank 2A. As compared with the first embodiment, the nitrification reaction in the reaction tank 2A can be more appropriately controlled. The other configuration is the same as that of the first embodiment, so the description will be omitted.

Fourth Embodiment
Next, a nitrogen-containing water treatment apparatus according to a fourth embodiment of the present invention will be described. FIG. 7 shows the configuration of the nitrogen-containing water treatment apparatus according to the fourth embodiment.

(Configuration of nitrogen-containing water treatment system)
As shown in FIG. 7, in the nitrogen-containing water treatment apparatus according to the fourth embodiment, unlike in the third embodiment described above, treated water at a plurality of locations of the reaction tank 2A is contained in one nitric acid meter 7. A plurality of pipes for each sampling are switchably connected to each other. Valves 11a, 11b, 11c and 11d are respectively provided in the respective pipes. Then, the water to be treated supplied to the nitric acid meter 7 is switched at each position in the reaction tank 2A by opening and closing the valves 11a to 11d.

  In addition, the nitric acid meter 7 is configured to be capable of independently measuring the nitric acid concentration of the water to be treated in multiple places of the reaction tank 2A according to the valve opened among the valves 11a to 11d, and the value of nitric acid concentration Can be supplied to the control unit 9. By this, unlike in the first embodiment, the nitric acid concentration of the water to be treated in a plurality of places of the reaction tank 2A can be measured only by installing one nitric acid meter 7. In addition to the method of supplying the water to be treated to the nitric acid meter 7, a tank for measurement is provided, the water to be treated at each position of the reaction tank 2A is supplied to the tank for measurement, and the nitric acid concentration is measured by the nitric acid meter 7. It is also possible to measure The other configurations and control of the gas supply amount are the same as in the first embodiment, and thus the description thereof is omitted.

  Also in the fourth embodiment, since the nitric acid concentration of the water to be treated can be measured at a plurality of locations in the reaction tank 2A, the same effect as that of the second embodiment can be obtained.

Fifth Embodiment
Next, an apparatus for treating nitrogen-containing water provided with a controller according to a fifth embodiment of the present invention will be described. FIG. 8 is a perspective transparent view showing the anaerobic tank 12 and the reaction tank 2A in the apparatus for treating nitrogen-containing water according to the fifth embodiment. In FIG. 8, the side wall on the front side of the drawing in the anaerobic tank 12 and the reaction tank 2A is not described for the following description. 9A and 9B are cross-sectional views of the reaction vessel taken along the lines A-A and B-B in FIG. 8, respectively. In addition, when the nitric acid meter is one, the nitric acid meter 7b shown by FIG. 9B does not exist.

  As shown in FIG. 8, the reaction tank 2A is composed of a single tank, and an anaerobic tank 12 is provided at the front stage of the reaction tank 2A along the flow direction of the water to be treated. Raw water flows into the anaerobic tank 12 from one side, and treated water anaerobically treated in the anaerobic tank 12 is supplied to the reaction tank 2A from the other side.

  Moreover, the plate-shaped aeration part 6 is provided in the inside of the reaction tank 2A substantially in the middle along the height direction of the reaction tank 2A. The aeration unit 6 is configured to be able to adjust the gas supply amount by the gas supply amount control unit 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 or nitric acid meters 7a and 7b capable of measuring nitric acid concentration is installed at a 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. When there is one nitric acid meter, 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 supplied measurement value of the nitric acid concentration. The gas supply amount control unit 10 controls the gas supply amount so as to be uniform throughout the aeration portion 6 in accordance with the supplied control signal, or for each predetermined section of the aeration portion 6. Control the gas supply rate. When there are a plurality of nitric acid meters, the nitric acid meters 7a and 7b supply the measured nitric acid concentration to the control unit 9. The control unit supplies a control signal to the gas supply control unit 10 according to a predetermined program in accordance with the supplied measurement value of the nitric acid concentration. The gas supply amount control unit 10 controls the gas supply amount for each predetermined section of the aeration 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 the thickness direction thereof is substantially parallel to the bottom surface of the reaction vessel 2A. In other words, the partition plate 13 is installed so that its surface is perpendicular to the bottom of the reaction vessel 2A. The partition plate 13 opens the upper portion and the lower portion of the partition plate 13 so that the inside of the reaction vessel 2A is partially partitioned.

  In the reaction tank 2A configured as described above, when aeration is performed by supplying a gas from the aeration unit 6 to the water to be treated while flowing the water to be treated, the aerated gas flows along the partition plate 13. Ascends and turns to the opposite surface side in a state of being divided by the partition plate 13. At the same time, since the water to be treated flows along the longitudinal direction of the reaction tank 2A, the aerated gas forms a spiral swirling flow as shown by arrow C in FIG. It will be dissolved. Similarly, the water to be treated travels along the longitudinal direction of the reaction vessel 2A while swirling in a spiral shape substantially centered on the longitudinal axis of the reaction vessel 2A. In addition, the gas supply amount from the aeration part 6 is suitably set according to conditions, such as the inflow of to-be-processed water, and the magnitude | size and shape of reaction tank 2A.

  Then, as shown by arrow C in FIG. 9A, which is a cross-sectional view taken along the line A-A at a position where the nitric acid meter 7, 7a is provided, oxygen such as air diffused from the aeration unit 6 is contained. The resulting gas passes through the gap in the upper portion of the partition plate 13 together with the water to be treated and swirls to the opposite side. Further, the water to be treated accompanying the swirl of the air passes through the gap of the lower portion of the partition plate 13 and reaches the lower side of the aeration unit 6. In this case, along the flow direction (arrow C) of the swirling flow of the water to be treated, the aerobic area 31 on the upstream side and the anoxic anaerobic area 32 on the downstream side coexist. In the aerobic area 31, the nitrification reaction is promoted by the aerobic nitrifying bacteria to constitute a nitrification area, while in the anoxic anaerobic area 32, the denitrification reaction is promoted by the anaerobic denitrifying bacteria to form the denitrification area. Configure.

  And as shown to FIG. 9A, in the upstream along the longitudinal direction of 2 A of reaction tanks, to-be-processed water was based on the gas supply_amount | feed_rate from the aeration part 6 more upstream than the position shown to FIG. 9A. Oxygen is dissolved. On the other hand, in the position shown to FIG. 9B, since it is the downstream side along the longitudinal direction of 2 A of reaction tanks, compared with the position shown to FIG. 9A, dissolved oxygen amount is large. Therefore, the area of the anoxic anaerobic area 32 shown in FIG. 9B is smaller than that of the anoxic anaerobic area 32 shown in FIG. 9A. That is, since the water to be treated flows from the upstream side to the downstream side along the longitudinal direction of the reaction tank 2A, the amount of contact with oxygen increases as it goes downstream, so the dissolved oxygen increases and the aerobic The area 31 is expanded. Thereby, in the water to be treated in the reaction tank 2A, the denitrification region tends to decrease as going from the upstream side to the downstream side. On the other hand, the nitrification region tends to increase as going from upstream to downstream.

From the above, on the upstream side of the reaction tank 2A, the denitrification reaction is promoted while the nitrification reaction coexists, and on the downstream side, the nitrification reaction is promoted while the denitrification reaction occurs. Thereby, as shown in FIG. 3A and FIG. 3B, since the denitrification reaction progresses immediately after the nitrification reaction is performed on the upstream side of the reaction tank 2A, nitrate nitrogen (NO ₃ -N) or nitrite system nitrogen _(nO 2 -N) is hardly emerge. Then, as proceeding to the downstream side of the reaction tank 2A, the nitric acid concentration is increased by promoting the nitrification reaction while reducing the total nitrogen concentration by the denitrification reaction. The other configurations are the same as those of the first and second embodiments, and thus the description thereof is omitted.

  According to the fifth embodiment described above, the swirl flow of the water to be treated is formed by supplying the gas from the aeration unit 6 while providing the partition plate 13 inside the reaction tank 2A. The nitric acid concentration can be controlled by the nitric acid meter 7 because nitric acid development by the nitrification reaction can be more efficiently suppressed on the upstream side and the nitrification reaction can be promoted on the downstream side while making the nitrification reaction and denitrification reaction coexist in a controlled manner. 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.

Sixth Embodiment
Next, an apparatus for treating nitrogen-containing water provided with a control apparatus according to a sixth embodiment of the present invention will be described. FIG. 10 is a block diagram showing an apparatus for treating nitrogen-containing water according to the sixth embodiment.

  As shown in FIG. 10, in the apparatus for treating nitrogen-containing water according to the sixth embodiment, unlike the second embodiment, a plurality of places, specifically, for example, the first, second, third, and fourth, are provided. Nitric acid meters 7a to 7d are respectively provided at four places of the predetermined position of. Specifically, as in the third embodiment, the nitric acid meters 7a to 7d are disposed over substantially the entire area of the reaction tank 2A, not the latter half portion along the flow direction of the water to be treated in the reaction tank 2A. . In addition, in arrangement | positioning over the whole area, even if nitric acid meter 7a-7d is put in order by equal intervals mutually, you may arrange in unequal intervals.

  In the sixth embodiment, the control unit 9 controls the supply amount of gas from the aeration unit 6a based on the measurement value of the nitric acid concentration by the nitric acid meter 7a. Moreover, the control part 9 controls the supply amount of the gas from the aeration part 6b based on the measured value of the nitric acid concentration by the nitric acid meter 7b. Similarly, the control unit 9 controls the amount of gas supplied from each of the aeration units 6c and 6d based on the measurement value of the nitric acid concentration by the nitric acid meter 7c and 7d. The other configurations are the same as those of the second and third embodiments, and thus the description thereof is omitted.

  In the sixth embodiment, the nitrification reaction in the reaction tank 2A is made as compared with the second embodiment by increasing the installation location of the nitric acid meter as compared with the second embodiment. And the denitrification reaction can be controlled more finely. Furthermore, the nitrification reaction and the denitrification reaction are controlled in more detail over the entire area of the reaction tank 2A by making the installation location of the nitric acid meter in the reaction tank 2A wider than in the third embodiment. Becomes possible.

(Modification of reaction tank and aeration part)
Next, modified examples relating to the reaction tank 2A and the internal aeration unit 6 in each embodiment of the present invention described above will be described.

(Modification 2)
11A to 11F are configuration diagrams showing reaction vessels 2A, 2B, 2C,... According to the second modification. As shown in FIG. 11A, in the reaction vessel 2A according to the modification 2 (the same applies to 2B, 2C,...), As in the second embodiment, a plurality of aeration portions 16a inside the reaction vessel 2A. , 16b, 16c are provided. These aeration units 16a to 16c are respectively controlled by gas supply amount control units 19a, 19b, and 19c that control the gas supply amount based on a control signal from control unit 9 (not shown in FIG. 11A). Ru. Further, unlike the second embodiment, the respective aeration units 16a to 16c are provided at predetermined intervals. That is, while the gas is supplied as the whole of the reaction tank 2A, the area to which the gas is supplied and the area to which the gas is not supplied are alternately and repeatedly sequentially or repeatedly along the flow direction of the water to be treated. It is formed. Since this makes it possible to alternately activate the activities of nitrifying bacteria of the aerobic bacteria and denitrifying bacteria of the facultative anaerobe in the reaction tank 2A, the explanation will be made in the third embodiment. As in the reaction tank 2A, in the reaction tank 2A, a region in which a nitrification reaction occurs and a region in which a denitrification reaction occurs can be formed with good controllability.

(Modification 3)
11B is a block diagram showing a reaction tank 2A according to a third modification. As shown in FIG. 11B, in the reaction vessel 2A according to the third modification, as in the second embodiment, a plurality of aeration units 26a, 26b, 26c, 26d and 26e are provided inside the reaction vessel 2A. ing. These aeration units 26a to 26e control the gas supply amount based on the control signal from control unit 9 (not shown in FIG. 11B), and supply amount control units 29a, 29b, 29c, It is controlled by 29d and 29e. Further, unlike the second embodiment, the control unit 9 selectively sets the aeration unit performing aeration and the aeration unit performing no aeration on the plurality of aeration units 26a to 26e. . In FIG. 11B, the aeration units 26a, 26c, and 26e perform aeration, and the aeration units 26b and 26d are controlled so as not to perform aeration. And the aeration part which performs aeration among these aeration parts 26a-26e and the aeration part which does not perform aeration are suitably selected according to the water quality | type property of the to-be-processed water which flows through the inside of reaction tank 2A. That is, while the gas is supplied as the whole of the reaction tank 2A, the area to which the gas is supplied and the area to which the gas is not supplied are alternately and repeatedly sequentially or repeatedly along the flow direction of the water to be treated. It is formed. As a result, while coexisting aerobic bacteria nitrifying bacteria and facultative anaerobic denitrifying bacteria in the reaction tank 2A, these activities can be sequentially alternately or repeatedly activated. Similar to the reaction vessel 2A according to the embodiment, in the reaction vessel 2A, the region where the nitrification reaction occurs and the region where the denitrification reaction occur can be formed with good controllability.

(Modification 4)
11C is a block diagram showing a reaction vessel 2A according to a fourth modification. As shown in FIG. 11C, in the reaction vessel 2A according to the fourth modification, a single aeration unit 36 is provided inside the reaction vessel 2A as in the first modification of the first embodiment. The aeration unit 36 is controlled by a gas supply control unit 39 that controls the gas supply based on a control signal from the control unit 9 (not shown in FIG. 11C). Further, unlike the third modification, the aeration unit 36 is controlled by the control unit 9 so as to sequentially or repeatedly perform aeration or a non-aeration as time passes.

  FIG. 11D is an example of a timing chart showing the timing of the presence or absence of this aeration. As shown in FIG. 11D, the time during which aeration is performed by the aeration unit 36 (ON in FIG. 11D) and the time during which aeration is not performed (OFF in FIG. 11D) It is set appropriately according to various conditions such as water quality. That is, while gas is supplied as a whole of reaction tank 2A, according to progress of time, time when gas is supplied to treated water, and time which are not supplied are set up alternately or repeatedly in order. Thereby, in the reaction tank 2A, while coexisting the nitrifying bacteria of the aerobic bacteria and the denitrifying bacteria of the facultative anaerobe, those activities may be alternately or repeatedly activated sequentially according to the passage of time. Since it is possible, as in the reaction vessel 2A described in the third embodiment, in the reaction vessel 2A, the region in which the nitrification reaction occurs and the region in which the denitrification reaction occurs can be formed with good controllability.

(Modification 5)
Furthermore, FIG. 11E is a block diagram which shows the reaction tank 2A by the modification 5. As shown in FIG. As shown in FIG. 11E, in the reaction vessel 2A according to the fifth modification, a single aeration unit 46 is provided inside the reaction vessel 2A as in the fourth modification. The aeration unit 46 is controlled by a gas supply control unit 49 that controls the gas supply based on a control signal from the control unit 9 (not shown in FIG. 11E). Further, in the reaction tank 2A, a plurality of carriers 43 carrying both the aerobic bacteria nitrifying bacteria and the facultative anaerobic denitrifying bacteria are charged. Then, when the gas is supplied from the aeration unit 46 into the reaction tank 2A, the inside of the reaction tank 2A is agitated, the carrier 43 flows in the treated water, and the carrier 43 is distributed substantially uniformly in the water to be treated. FIG. 11F is a cross sectional view showing a cross sectional structure of the carrier 43. As shown in FIG.

  As shown in FIG. 11F, the carrier 43 is made of a particulate resin carrier, and as long as the carrier 43 can retain bacteria even when it flows in the water to be treated, its size and shape are various sizes and shapes. Can be adopted. For example, it is preferable to have a cylindrical shape, a spherical shape, or the like, and have an outer diameter of about several millimeters. Also, aerobic nitrification bacteria are mainly carried in the nitrification reaction zone on the surface portion of the carrier 43, and facultative anaerobic denitrification bacteria are mainly carried in the denitrification reaction zone. Specifically, the carrier 43 is a facultative anaerobic denitrifying bacteria that contributes to an anaerobic denitrification reaction in a form surrounded by aerobic nitrifiers that contribute to the nitrification reaction in the outer region 43a. The surface area is made to carry two layers of microbial membranes which are respectively present in the inner region 43b as a dominant species. Thereby, in the carrier 43 in the water to be treated, the nitrifying bacteria located on the outer side are regarded as aerobic conditions as dominant species, and the denitrifying bacteria located on the inner side are anaerobic conditions in a form surrounded by the nitrifying bacteria. Secured.

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

(Modification 6)
Next, a sixth modification will be described. FIG. 12A is a configuration diagram of a nitrogen-containing water treatment apparatus according to Modification 6 corresponding to FIG. 5 in the second embodiment. FIG. 12B is a graph showing NH ₄ -N, NO ₂ -N, and NO ₃ corresponding to FIG. 3A measured along the flow of water to be treated in the reaction tank to explain the target nitrification rate and the measured nitrification rate. It is a graph which shows each nitrogen concentration of -N, and a total nitrogen concentration. In this modification 6, a pair of ammonia meter is used as a denitrification confirmation means.

  That is, as shown in FIG. 12A, in the sixth modification, unlike the second embodiment, the first upstream side along the flow direction of the water to be treated instead of the nitric acid meter 7 of the reaction tank 2A. A nitrification rate meter 58 comprising a pair of ammonia gauges, an ammonia gauge 58a and a second ammonia gauge 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 supplied to the control unit 9, respectively. The other configuration is the same as that of the second embodiment, so the description will be omitted.

Next, a control method by the control unit 9 in the case where the nitrification velocimeter 58 including the pair of first ammonia gauges 58a and the second ammonia gauge 58b is used as the 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. The first ammonia concentration NH1 and the second ammonia concentration NH2 are supplied to the control unit 9, respectively. The controller 9 calculates the measured nitrification rate from the supplied first ammonia concentration NH1 and the second ammonia concentration NH2 (NH1> NH2). Specifically, 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 therefrom, the measured nitrification rate is calculated based on the equation (11). The measured nitrification speed corresponds to the absolute value of the slope of the solid line shown in FIG. 12B, and the measured nitrification speed may differ as indicated by two solid lines depending on the installation position of the nitrification velocimeter 58.

On the other hand, the final ammonia concentration (target ammonia concentration) NH ₃ as a treated water target value is set in advance for each of the various reaction vessels 2A. Control unit 9, and the target ammonia concentration NH _3, from ammonia concentration NH1 Metropolitan measured in the position of the first ammonia meter 58a, and calculates the nitrification rate (target nitrification rate) as a reference, the control unit 9 Store in the recording area (not shown). The 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. 12B.

And as shown to FIG. 12A, the control part 9 measures the nitrification speed between the 1st ammonia meter 58a and the 2nd ammonia meter 58b, ie, the measured nitrification speed measured by the nitrification rate meter 58, The gas supply amount from the aeration unit 6 on the upstream side of at least the second ammonia meter 58 b is controlled so as to be less than the nitrification speed. Thereby, the progress of the nitrification reaction on the upstream side of the second ammonia meter 58 b can be suppressed, and the denitrification reaction in this region can be promoted. In addition, even if the measured nitrification rate is less than the target nitrification rate, the ammonia concentration may not decrease to the desired target ammonia concentration NH ₃ on the outflow side of the reaction tank 2A if it becomes too slow. Then, according to the knowledge obtained from the experiment of the inventor, it is preferable to make the measured nitrification rate larger than half of the target nitrification rate. That is, the control unit 9 controls the gas supply amount from the aeration unit 6 such that the following equation (13) holds.

  Specifically, when the measured nitrification rate with respect to the target nitrification rate becomes larger than the range set by equation (13), that is, when the measured nitrification rate becomes equal to or higher than the target nitrification rate, the nitrification reaction proceeds. It will be too much. Therefore, the control unit 9 reduces the amount of air supplied from the aeration units 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 nitrification reaction not to proceed excessively in the reaction tank 2A. On the other hand, when the measured nitrification rate with respect to the target nitrification rate becomes smaller than the range set by equation (13), that is, when the measured nitrification rate becomes half or less of the target nitrification rate, the nitrification reaction is suppressed. It will be too much. Therefore, the control unit 9 increases the amount of air supplied from the aeration units 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 nitrification reaction to be performed at a desired nitrification rate in the reaction tank 2A.

  In the modification 6 described above, the control of the denitrification processing performed by the nitric acid meter in the embodiment described above is performed using a pair of ammonia gauges. Thereby, in the reaction tank 2A, while coexisting the nitrifying bacteria of the aerobic bacteria and the denitrifying bacteria of the facultative anaerobe, both activities can be activated. Thereby, in the reaction tank 2A, the nitrification reaction and the denitrification reaction can coexist with good controllability.

  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 are possible. For example, the numerical values listed in the above-described embodiment are merely examples, and different numerical values may be used as needed.

  Moreover, in the above-mentioned embodiment, although biological treatment of nitrogen-containing water by what is called a standard activated sludge method was explained, the present invention is not necessarily limited to this method, and various treatment methods using an aerobic tank It can be applied to Specifically, the present invention relates to AO (anaerobic-aerobic) method, A2O (anaerobic-anoxic-aerobic) method, nitrification + endogenous denitrification method, multistage step inflow type nitrification denitrification method, and multistage step inflow type A2O It is possible to apply to the processing method of various nitrogen containing water which uses an aerobic tank, such as a method.

  Moreover, it is also possible to employ | adopt a deep tank swirl flow reaction tank about 10 m in depth, and a shallow tank reaction tank about 5 m as reaction tank 2A, 2B, 2C.

  Further, in the above embodiment, the control unit and the gas supply control unit are separately provided, but these control units and the gas supply control unit can be configured from the same control unit, It is also possible to constitute from three or more separate bodies having similar functions.

  Moreover, in the above-mentioned modification 6, the nitrification rate meter is comprised of a plurality of ammonia gauges, specifically, a pair of ammonia gauges, and the nitrification rate of the water to be treated in the reaction tank 2A is calculated using this nitrification rate meter. Although it measures it, a nitrification rate meter is not necessarily limited to a pair of ammonia meter, and even if it adopts three or more ammonia meters, even if it adopts various devices which can measure a nitrification rate good.

1 First sedimentation tank 2A Any one of a plurality of reaction tanks 2B, 2C Other reaction tanks 2a, 2b, 2c, 2d aerobic tank 3 solid-liquid separation tank 4a separated liquid 4b activated sludge 5 sludge return path 6, 6a, 6b, 6c, 6d, 16a, 16b, 26a, 26b, 26c, 26d, 26e, 36, 46 Aeration unit 7 Nitrate meter 7a Nitrate meter 7b at the first predetermined position nth predetermined position Nitrate meter 8 Blower 9 Control part 10, 10a, 10b, 10c, 10d, 19a, 19b, 19c, 29a, 29b, 29c, 29d, 29e, 39, 49 Gas supply control part 12 Anaerobic tank 12a Motor 12b Stirring part 13 Partition Plate 31 Aerobic Region 32 Anaerobic Anaerobic Region 43 Carrier 43a Outer Region 43b Inner Region 58 Nitrification Rate Meter 58a First Ammonia Meter 58b Second Ammonia Meter 61 Flow Amount control means 81 Upstream denitrification section 82 Downstream side nitrification section 83 Section 84, 85 until aeration effect due to aeration is expressed Section 88, 89 DO meter where control of the aeration means due to the nitric acid meter is performed

Claims (6)

Multiple reactors of the same type connected in parallel;
Flow control means for controlling the flow 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 nitrated to nitric acid according to the flow of nitrogen-containing water, and nitric acid is denatured at a desired progress of denitrification reaction at each position along the flow direction of the nitrogen-containing water A diffuser for supplying a gas to the nitrogen-containing water over substantially the entire flow direction so as to be nitrided;
In any one reaction vessel of the plurality of reaction vessels, the nitric acid concentration of the nitrogen-containing water is provided at a position controllable at 5.0 mg / L or less halfway along the flow direction of the nitrogen-containing water , Nitric acid concentration measuring means for measuring the nitric acid concentration of the nitrogen-containing water in order to confirm the progress of denitrification reaction at an intermediate position ;
Based on the nitric acid concentration of the nitrogen-containing water that has been measured by the nitric acid concentration measurement means, as Oite nitrate to the middle position location is denitrified in progress of the desired denitrification, the nitrogen-containing water The first control method for controlling the gas supply amount by the aeration means in a section in which the control of the aeration means due to the nitric acid concentration measurement means is performed, including at least the upstream side of the nitric acid concentration measurement means along the flow direction Gas supply control means of
The same position or different position in the middle of each reaction tank in the section where the control of the aeration means caused by the nitric acid concentration measurement means is performed excluding the section until the aeration effect by the aspiration means appears provided at a predetermined position corresponding to a position above the middle position, and the dissolved oxygen concentration measuring means for measuring a dissolved oxygen concentration of the nitrogen-containing water at the predetermined position,
The nitric acid concentration measuring means is provided based on the dissolved oxygen concentration of the nitrogen-containing water measured by the dissolved oxygen concentration measuring means provided at the predetermined position of the reaction vessel provided with the nitric acid concentration measuring means A means for setting a dissolved oxygen target concentration at the predetermined position of another reaction vessel other than the reaction vessel;
As the measured value of the dissolved oxygen concentration in the nitrogen-containing water in the predetermined position of the other reactor other than the reactor that the nitric acid concentration measurement means it is provided coincides with the target density, the nitrate concentration measurement of the reaction vessel a second gas supply control means for controlling the supply amount of the gas by the air diffuser means in a section where the control of the aeration means due to the means is performed,
And a sewage treatment apparatus using activated sludge. A plurality of reactors of the same type connected in parallel;
Flow control means for controlling the flow 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 nitrated to nitric acid according to the flow of nitrogen-containing water, and nitric acid is denatured at a desired progress of denitrification reaction at each position along the flow direction of the nitrogen-containing water A diffuser for supplying a gas to the nitrogen-containing water over substantially the entire flow direction so as to be nitrided;
In any one reaction vessel of the plurality of reaction vessels, the nitric acid concentration of the nitrogen-containing water is 5.0 at each predetermined position of the first to n (n is a natural number of 2 or more) along the flow direction of the nitrogen-containing water Nitric acid concentration measuring means provided at controllable positions below mg / L and respectively measuring the nitric acid concentration of the nitrogen-containing water to confirm the progress of the denitrifying reaction at each of the first to nth predetermined positions ;
Based on the nitric acid concentration of the nitrogen-containing water that has been measured by the nitric acid concentration measuring means of each predetermined position of the first 1 to n, Oite nitrate throughout localization location of the first 1 to n of the desired denitrification The nitric acid concentration measurement of each of the first to n predetermined positions including at least the upstream side of each of the first to n predetermined positions along the flow direction of the nitrogen-containing water so as to be denitrified by the progress degree a first gas supply amount control means for controlling each of the feed rate of the gas by the air diffuser means in each section to the control of the air diffuser means caused performed means,
Control of the aeration means caused by the nitric acid concentration measurement means at each of the first to n predetermined positions except for the section until the aeration effect of the aeration means appears in each reaction tank It is provided at each predetermined position of 1a to na corresponding to each of the first to n predetermined positions which is the same position as or different from the predetermined position of the first to n in the section, respectively. Dissolved oxygen concentration measuring means for respectively measuring the dissolved oxygen concentration of the nitrogen-containing water at each predetermined position of
Based on the dissolved oxygen concentration in the nitrogen-containing water that has been measured by the dissolved oxygen concentration measuring means provided in each predetermined position of the first 1a~na reaction vessel in which the nitric acid concentration measurement means is provided, the nitric acid concentration A means for individually setting a dissolved oxygen target concentration at each of the predetermined positions of the first to na of the reaction vessels other than the reaction vessel provided with the measurement means ;
The measurement values of the dissolved oxygen concentration of the nitrogen-containing water at each predetermined position of the first to na of the reaction vessels other than the reaction vessel provided with the nitric acid concentration measuring means respectively match the target concentration A second gas supply amount for controlling the gas supply amount by the aeration means in each section in which control of the aeration means is performed due to the nitric acid concentration measurement means at each of the first to n predetermined positions of the reaction tank Control means,
And a sewage treatment apparatus using activated sludge. In one of the reaction vessels of the same type connected in parallel and controlled such that the flow rate of the nitrogen-containing water flowing into the same, the way along the flow direction of the nitrogen-containing water A nitric acid concentration measuring means for measuring the nitric acid concentration of the nitrogen-containing water to confirm the progress of the denitrification reaction , provided at a position where the nitric acid concentration of the nitrogen-containing water can be controlled to 5.0 mg / L or less at the position ; In each reaction tank, ammonia contained in the nitrogen-containing water is nitrified to nitric acid according to the flow of nitrogen-containing water, and the progress of desired denitrification reaction of nitric acid at each position along the flow direction of the nitrogen-containing water Aeration means for supplying a gas over substantially the entire flow direction to the nitrogen-containing water so as to be denitrified by degree, and a section until the aeration effect is exhibited by the aeration means measuring the nitrate concentration Control of air diffuser means due provided at a predetermined position corresponding to the middle position and the same position or different positions the middle position in the section to be performed in unit, for measuring the dissolved oxygen concentration of the nitrogen-containing water It is a control device of the aeration means used with respect to the said aeration means in the case of having a dissolved oxygen concentration measurement means ,
Based on the nitric acid concentration of the nitrogen-containing water that has been measured by the nitric acid concentration measurement means, as Oite nitrate to the middle position location is denitrified in progress of the desired denitrification, the nitrogen-containing water along the flow direction, before Symbol comprising at least an upstream side of the nitric acid concentration measuring means, to control the supply amount of the gas by the air diffuser means in the interval control is performed in the aeration unit due to the nitric acid concentration measurement means the 1 gas supply amount control means,
Based on the dissolved oxygen concentration in the nitrogen-containing water that has been measured by the dissolved oxygen concentration measuring means before Symbol predetermined position of the reaction vessel in which the nitric acid concentration measurement means is provided, the reactor in which the nitric acid concentration measurement means is provided A means for individually setting a dissolved oxygen target concentration at the predetermined position of another reaction tank other than the reaction vessel ;
As the measured value of the dissolved oxygen concentration in the nitrogen-containing water in the predetermined position of the other reactor other than the reactor that the nitric acid concentration measurement means it is provided coincides with the target density, the nitrate concentration measurement of the reaction vessel a second gas supply amount control means for controlling the supply amount of the gas by the air diffuser means in the interval control is performed in the aeration unit due to the means,
A control device of the air diffusion means characterized by comprising: Flow rate of nitrogen-containing water flowing is controlled to be the same among the plurality of reaction vessels of the same type connected in parallel, in any one reaction vessel, the along the flow direction of the nitrogen-containing water 1 to n (n is a natural number of 2 or more) provided at positions where the nitric acid concentration of the nitrogen-containing water can be controlled to 5.0 mg / L or less at each predetermined position, in order to confirm the progress of denitrification reaction Ammonia concentration measurement means for measuring the nitric acid concentration of nitrogen-containing water is included , and in each reaction vessel, ammonia contained in the nitrogen-containing water is nitrated to nitric acid according to the flow of nitrogen-containing water, and in the flow direction of the nitrogen-containing water A diffuser for supplying a gas over substantially the entire flow direction to the nitrogen-containing water so that nitric acid is denitrified at a desired degree of progress of denitrification reaction at each position along the line; Diffuse effect by air means The control of the air diffuser means due to nitric acid concentration measurement means of each predetermined position of the 1~n or different each predetermined position and each same location of the first 1~n or in each section to be performed except for the interval until the In the case of having a dissolved oxygen amount measuring means for measuring the dissolved oxygen concentration of the nitrogen-containing water , provided at each predetermined position of the 1a to na corresponding to each of the 1st to nth predetermined positions. It is a control device of the aeration means used to the aeration means concerned,
Based on each nitric acid concentration of the nitrogen-containing water measured by the nitric acid concentration measuring means at each of the first to n predetermined positions, the progress degree of denitrification reaction desired for nitric acid at each of the first to n predetermined positions The nitric acid concentration measuring means at each of the first to n predetermined positions including at least the upstream side of each of the first to n predetermined positions along the flow direction of the nitrogen-containing water so as to be denitrified at First gas supply amount control means for controlling the supply amount of gas by the aeration means in each section in which the control of the aeration means resulting therefrom is performed;
Based on the dissolved oxygen concentration of the nitrogen-containing water that has been measured at each specified position of the first 1a~na reaction vessel in which the nitric acid concentration measurement means is provided, except the reaction vessel in which the nitric acid concentration measurement means is provided Means for respectively setting the dissolved oxygen target concentration at each of the predetermined positions of the first to na of the other reaction vessels;
The measurement values of the dissolved oxygen concentration of the nitrogen-containing water at each predetermined position of the first to na of the reaction vessels other than the reaction vessel provided with the nitric acid concentration measuring means respectively match the target concentration A second gas supply amount for controlling the gas supply amount by the aeration means in each section in which control of the aeration means is performed due to the nitric acid concentration measurement means at each of the first to n predetermined positions of the reaction tank Control means,
A control device of the air diffusion means characterized by comprising: A flow control step of controlling the flow rates of nitrogen-containing water flowing into the plurality of reaction vessels of the same type connected in parallel to be the same;
Ammonia contained in the nitrogen-containing water is nitrated to nitric acid according to the flow of the nitrogen-containing water in each reaction tank, and the nitric acid is at the desired progress of denitrification reaction at each position along the flow direction of the nitrogen-containing water Supplying a gas to the nitrogen-containing water substantially across the flow direction so as to be denitrified;
In any one of the reaction vessel of the plurality of reaction vessels, Oite a nitric acid concentration of said nitrogen-containing water controllable located below 5.0 mg / L at a position midway along the flow direction of the nitrogen-containing water denitrification A nitric acid concentration measuring step of measuring the nitric acid concentration of the nitrogen-containing water to confirm the progress of the reaction;
Based on the nitric acid concentration of the nitrogen-containing water measured in the nitric acid concentration measurement step, in the flow direction of the nitrogen-containing water so that nitric acid is denitrified at the intermediate position at a desired progress of denitrification reaction First gas supply amount control for controlling the gas supply amount in the aeration step in a section in which control of the aeration step caused by the nitric acid concentration measurement step is performed, including at least the upstream side from the halfway position along Step and
A each reaction vessel, or the same position as the middle position in the section where the control of the aeration step due to the nitric acid concentration measuring step, except the section between diffuser effect by the air diffuser step is expressed is performed Or a dissolved oxygen measurement step of measuring the dissolved oxygen concentration of the nitrogen-containing water at a predetermined position corresponding to the middle position, which is a different position;
Based on the measured value of the dissolved oxygen concentration in the nitrogen-containing water that has been measured at the predetermined position in the reaction vessel was measured nitric acid concentration of said nitrogen-containing water, other than the reaction vessel was measured nitric acid concentration of the nitrogen-containing water A target dissolved oxygen concentration setting step of setting a target dissolved oxygen concentration at the predetermined position of the reaction tank;
The nitric acid concentration of the reaction vessel is determined so that the measured value of the dissolved oxygen concentration of the nitrogen-containing water at the predetermined position of the reaction vessel other than the reaction vessel where the nitric acid concentration of the nitrogen-containing water is measured matches the target concentration. A second gas supply control step of controlling a supply amount of gas in the aeration step in a section in which control of the aeration step resulting from the measurement step is performed;
And a computer readable recording medium having recorded thereon a program. A flow control step of controlling the flow rates of nitrogen-containing water flowing into the plurality of reaction vessels of the same type connected in parallel to be the same;
Ammonia contained in the nitrogen-containing water is nitrated to nitric acid according to the flow of the nitrogen-containing water in each reaction tank, and the nitric acid is at the desired progress of denitrification reaction at each position along the flow direction of the nitrogen-containing water Supplying a gas to the nitrogen-containing water substantially across the flow direction so as to be denitrified ;
In any one reaction vessel of the plurality of reaction vessels, the nitric acid concentration of the nitrogen-containing water is 5.0 at each predetermined position of the first to n (n is a natural number of 2 or more) along the flow direction of the nitrogen-containing water A nitric acid concentration measuring step of measuring the nitric acid concentration of the nitrogen-containing water in order to confirm the progress of desired denitrifying reaction by the nitric acid at a position controllable to less than mg / L.
Based on each nitric acid concentration of the nitrogen-containing water measured in the nitric acid concentration measurement step, the nitric acid is denitrified at each of the first to n predetermined positions at a desired progress of denitrifying reaction, Gas in the aeration step in each section in which control of the aeration step caused by the nitric acid concentration measurement step is performed, including at least the upstream side from each of the first to n predetermined positions along the flow direction of nitrogen-containing water A first gas supply amount control step of controlling the supply amount of
A each reaction vessel, each of said first 1~n in each section to control the aeration step due to the nitrate concentration measurement step, except the section between diffuser effect by the air diffuser step is expressed is performed dissolved oxygen concentration measurement step of measuring respective dissolved oxygen concentration in the nitrogen-containing water at each predetermined position of the 1a~na corresponding to each predetermined position of a predetermined position and are each the same location or different locations said first 1~n When,
Other than the reaction tank in which the nitric acid concentration was measured based on the measurement value of the dissolved oxygen concentration of the nitrogen-containing water measured at each predetermined position of the first to the first in the reaction tank in which the nitric acid concentration of the nitrogen-containing water was measured A target dissolved oxygen concentration setting step of setting a target dissolved oxygen concentration at each of the predetermined positions of the first to na of the other reaction tank;
The measurement value of the dissolved oxygen concentration of the nitrogen-containing water at each predetermined position of the first to na of the reaction vessels other than the reaction vessel where the nitric acid concentration of the nitrogen-containing water is measured matches the target concentration respectively A second gas supply for controlling the gas supply amount in the aeration step in each section in which the control of the aeration step caused by the nitric acid concentration measurement step at each of the first to nth predetermined positions of the reaction vessel is performed Control step,
And a computer readable recording medium having recorded thereon a program.

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