JP6413150B2 - Nitrogen removing device and method of remodeling nitrogen removing device - Google Patents

Description

  The present invention relates to a nitrogen removing apparatus and a method for modifying the nitrogen removing apparatus.

  Biological nitrogen removal is known as a nitrogen removal (denitrification) method for water to be treated containing organic nitrogen compounds. Biological nitrogen removal involves nitrification in which ammonia nitrogen contained in water to be treated is oxidized to nitrite nitrogen or nitrate nitrogen by the action of nitrifying bacteria in an aerobic atmosphere by aeration, and sublimation in an anaerobic atmosphere. It is carried out by a denitrification reaction in which nitrate nitrogen or nitrate nitrogen is reduced to nitrogen gas by the action of denitrifying bacteria.

  As biological nitrogen removal, a treatment method is known in which nitrification reaction and denitrification reaction are carried out in a single reaction tank by intermittently adding water to be treated. This treatment method secures a time zone during which the denitrification reaction proceeds by making the inside of the tank a relatively anaerobic atmosphere by utilizing the high oxygen consumption activity of the treated water when the treated water is added. When the charging is stopped, the time zone in which the nitrification reaction proceeds can be secured by making the inside of the tank a relatively aerobic atmosphere.

  Patent Document 1 describes a processing method for clearly partitioning an aerobic processing region and an anaerobic processing region by providing a partition in a reaction tank. This treatment method stably forms an anaerobic atmosphere even when the water to be treated becomes undesired for nitrogen removal, such as when the BOD / TN (total nitrogen) ratio of the water to be treated is 3 or less. can do.

Japanese Patent No. 3649632

  However, in the treatment method described in Patent Document 1, some water to be treated may flow from the anaerobic treatment region to the aerobic treatment region via the liquid phase part of the space above the partition wall. Thus, there existed a subject that nitrogen removal became inadequate because to-be-processed water moved to an aerobic treatment area | region, without fully staying in an anaerobic treatment area | region.

  An object of this invention is to provide the nitrogen removal apparatus which enables more stable nitrogen removal, and the remodeling method of a nitrogen removal apparatus.

According to the first aspect of the present invention, the nitrogen removal apparatus has a single aerobic treatment region and an anaerobic treatment region, and performs biological denitrification of water to be treated containing an organic nitrogen compound. A reaction tank composed of a tank, and one or more treatment tank sets that are provided downstream of the reaction tank, and include an anaerobic treatment tank that forms an anaerobic treatment area and an aerobic treatment tank that forms an aerobic treatment area, and A raw water supply pipe that is provided in an upper part of the reaction tank and supplies the water to be treated, a partition that partitions the liquid phase part of the reaction tank into the aerobic treatment area and the anaerobic treatment area, and the reaction tank. a raw water inlet is an outlet of the formed the raw water supply pipe, the farthest Oite plane on及 beauty to the height direction having a length and a width of the reactor from the raw water inlet on the partition wall a is, the aerobic treatment and the anaerobic treatment region provided in a part of the lower end of the partition wall A communication port for communicating the region, a circulation channel for circulating the treated water from the aerobic treatment region to the most upstream part of the anaerobic treatment region of at least one of the reaction vessel and the treatment vessel group; A second raw water supply pipe for supplying a part of the treated water supplied from the raw water supply pipe to the anaerobic treatment tank.

According to such a configuration, the liquid phase part of the reaction tank is divided into the anaerobic treatment region and the aerobic treatment region by the partition wall, and the communication port that communicates the anaerobic treatment region and the aerobic treatment region is the raw water inlet. It is provided in the position farthest from Thereby, sufficient residence time required for denitrification of the to-be-processed water thrown in from the raw | natural water inlet can be ensured, and more stable nitrogen removal can be performed.
Moreover, it can prevent that the to-be-processed water of an anaerobic process area | region flows into an aerobic process area | region in the liquid level vicinity of to-be-processed water.

  In the nitrogen removal apparatus, the raw water inlet and the circulating liquid inlet that is the outlet of the circulation channel are opened to the reaction tank, and the raw water inlet and the circulating liquid inlet are arranged close to each other. It's okay.

  According to such a configuration, since the BOD component contained in the water to be treated and the nitrite-nitrate nitrogen component contained in the circulating liquid are more in contact with each other, the efficiency of nitrogen removal can be improved.

According to the second aspect of the present invention, a method for remodeling a nitrogen removing apparatus is provided from a single tank that performs anaerobic treatment and aerobic treatment in biological denitrification of water to be treated containing organic nitrogen compounds. A reaction tank, an anaerobic treatment tank that is provided downstream of the reaction tank and forms an anaerobic treatment area, and an aerobic treatment tank that forms an aerobic treatment area, and the reaction tank A raw water supply pipe for supplying the water to be treated, a raw water inlet that is an outlet of the raw water supply pipe formed in the reaction tank, and a discharge for discharging the water to be treated from the reaction tank A nitrogen removal device having a pipe and a circulation channel for circulating the treated water from the discharge pipe to the reaction tank, wherein the liquid phase part of the reaction tank is anaerobic treatment region and anaerobic A partition partitioning into a treatment area, the reaction from the raw water inlet Of a position farthest Oite on a plane 及 beauty height Direction having a length and a width, the anaerobic treatment region provided in a part of the lower end of the partition wall between the said aerobic treatment region A step of forming a partition having a communication port for communication, a second raw water supply pipe for supplying a part of the treated water supplied from the raw water supply pipe to the anaerobic treatment tank, Moving the outlet of the circulation channel to the most upstream part of the anaerobic treatment region.

  According to the present invention, the liquid phase part of the reaction tank is partitioned into an anaerobic treatment region and an aerobic treatment region by the partition wall, and a communication port for communicating the anaerobic treatment region and the aerobic treatment region is possible from the raw water input port. As far as possible. Thereby, sufficient residence time required for denitrification of the to-be-processed water thrown in from the raw | natural water inlet can be ensured, and more stable nitrogen removal can be performed.

It is a schematic block diagram of the nitrogen removal apparatus of 1st embodiment of this invention. It is a perspective view of the reaction tank of a first embodiment of the present invention. It is a schematic block diagram explaining the remodeling process of 1st embodiment of this invention. It is a schematic block diagram explaining the remodeling process of 1st embodiment of this invention. It is a schematic block diagram of the nitrogen removal apparatus of 2nd embodiment of this invention. It is a perspective view of the reaction tank of 3rd embodiment of this invention.

(First embodiment)
Hereinafter, the nitrogen removal apparatus 1 of 1st embodiment of this invention is demonstrated in detail with reference to drawings. The nitrogen removing apparatus 1 of this embodiment is an apparatus that performs biological denitrification in a facility such as a human waste treatment plant. To-be-treated water W (waste water containing human waste E and septic tank sludge S) to be treated by the nitrogen removing device 1 is an organic nitrogen compound, SS (floating matter), phosphorus content, BOD (biochemical oxygen demand), Contains COD (chemical oxygen demand) and the like.

  As shown in FIG. 1, the nitrogen removal apparatus 1 of this embodiment is a reaction in which raw water of the treated water W1 supplied from the mixing tank 2 and the mixing tank 2 into which the human waste E and the septic tank sludge S1 are introduced, is introduced. A tank 3, a first stirring tank 4 into which the water to be treated W2 discharged from the reaction tank 3 is introduced, an aeration tank 5 into which the water to be treated W3 discharged from the first stirring tank 4 is introduced, and an aeration tank 5, the second agitation tank 6 into which the water to be treated W4 discharged from 5 is introduced, the deaeration tank 7 into which the water to be treated W5 discharged from the second agitation tank 6 is introduced, and the deaeration tank 7. Sludge separation tank 8 into which treated water W6 is introduced.

The first stirring tank 4 and the second stirring tank 6 are anaerobic treatment tanks that perform anaerobic treatment that does not require dissolved oxygen. The aeration tank 5 and the deaeration tank 7 are aerobic treatment tanks that perform aerobic treatment that requires dissolved oxygen.
Here, a set of tanks composed of an anaerobic treatment tank and an aerobic treatment tank is defined as a treatment tank set. The nitrogen removing apparatus 1 has a first processing tank set 41 and a second processing tank set 42 which are two processing tank sets. Note that the number of processing tank groups is not limited to two, and one processing tank group may be provided downstream of the reaction tank 3, or three or more processing tank groups may be provided.

The mixing tank 2 and the reaction tank 3 are connected via a raw water supply pipe 9. The reaction tank 3 and the first stirring tank 4 are connected via a discharge pipe 10.
The nitrogen removing device 1 has a second raw water supply pipe 16 that branches from the raw water supply pipe 9 and introduces the raw water of the treated water W1 into the first stirring tank 4. That is, the water to be treated W1 discharged from the mixing tank 2 is supplied to the reaction tank 3 and the first stirring tank 4.

The nitrogen removing device 1 has a circulation line 12 that circulates a part of the water to be treated W2 discharged from the reaction tank 3 to the reaction tank 3 as a circulating liquid R. The circulation line 12 branches off from the discharge pipe 10. Alternatively, the circulation line 12 may be taken out from the aerobic treatment region A2 of the reaction tank 3.
The circulation line 12 has a branch line 31 for supplying the circulating fluid R to the aerobic processing region A2, and a flow rate adjusting device such as a valve for adjusting the flow rate of the circulating fluid R can be provided.
Further, the nitrogen removing device 1 includes a return line 11 for returning at least a part of the sludge S2 separated in the sludge separation tank 8 (return sludge S3) to the reaction tank 3.

  The reaction tank 3 is divided into an anaerobic treatment region A1 on the upstream side and an aerobic treatment region A2 on the downstream side by a partition wall 15. The raw water supply pipe 9 is connected to the anaerobic treatment region A1 of the reaction tank 3. The discharge pipe 10 is connected to the aerobic treatment region A2 of the reaction tank 3. The anaerobic treatment region A1 and the aerobic treatment region A2 communicate with each other through a communication port 19 that is an opening formed in the partition wall 15.

  The mixing tank 2 is a tank that mixes the introduced human waste E and the septic tank sludge S1. The mixing tank 2 is preferably provided with a device for promoting homogenization by mixing the human waste E and the septic tank sludge S1, such as a stirring device for stirring the human waste E and the septic tank sludge S1. Further, it is preferable to provide a pretreatment device for removing impurities contained in the human waste E and the septic tank sludge S1 in the previous stage of the mixing tank 2.

The reaction tank 3 has an aerobic treatment region A2 for performing an aerobic treatment that requires dissolved oxygen and an anaerobic treatment region A1 for performing an anaerobic treatment that does not require dissolved oxygen, and removes nitrogen from the water W1 to be treated. It is a tank to perform.
The reaction tank 3 includes a reaction tank body 13 having a single structure, an aeration device 14, and a partition wall 15 provided inside the reaction tank body 13. The reaction tank body 13 is composed of a single tank. The aeration apparatus 14 is disposed on the bottom surface of the reaction tank 3.

As shown in FIG. 2, the reaction vessel main body 13 is a rectangular parallelepiped tank, for example, and has four side walls 21, an upper surface 22, and a bottom surface 23. In the xyz orthogonal coordinate system, the x-axis direction is the length, the y direction is the width, and the z direction is the height. The shape of the reaction vessel main body 13 is not limited to this, and for example, the shape seen from above may be circular.
In the reaction tank 3, the water to be treated W1 introduced from the mixing tank 2 is stored. The liquid level L of the water to be treated W1 is adjusted so as to maintain a predetermined height from the bottom surface 23 of the reaction tank main body 13. That is, the internal space of the reaction tank 3 is divided into a liquid phase part F by the water to be treated W1 and a gas phase part G above the liquid level L of the water to be treated.

The partition wall 15 is a rectangular plate-like member that divides the internal space of the reaction tank body 13 into an anaerobic processing region A1 and an aerobic processing region A2. The aerobic treatment area A2 defined by the partition wall 15 is aerated from below by the aeration apparatus 14 installed on the bottom surface 23.
The upper end of the partition 15 is formed so as to be higher than the liquid level L of the water to be treated W1. That is, in the vicinity of the liquid level L of the water to be treated W1, the water to be treated W1 in the anaerobic treatment area A1 does not flow into the aerobic treatment area A2.
A gap C is formed between the upper end of the partition wall 15 and the upper surface 22 of the reaction tank body 13. That is, in the internal space of the reaction tank 3, the space above the liquid level L of the water to be treated W <b> 1 is not partitioned by the partition wall 15.

  The partition wall 15 is formed with a communication port 19 through which the water to be treated W1 in the anaerobic treatment area A1 flows into the aerobic treatment area A2. The communication port 19 is formed at the lower end of the partition wall 15 and at one end portion in the width direction of the partition wall 15. The communication port 19 has a rectangular shape.

The reaction tank body 13 is formed with a raw water inlet 17 which is an outlet of the raw water supply pipe 9. That is, the water to be treated W1 mixed in the mixing tank 2 is input to the reaction tank 3 from the raw water input port 17.
The water to be treated W <b> 1 is introduced from the raw water inlet 17 into the anaerobic treatment area A <b> 1 of the reaction tank 3, flows into the aerobic treatment area A <b> 2 through the communication port 19, and is discharged from the discharge pipe 10.

  The raw water inlet 17 is formed on the side wall 21b of the anaerobic treatment region A1 of the reaction tank body 13. The raw water input port 17 is provided at a position farthest from the communication port 19 by a linear distance on the xy plane. Since the communication port 19 of the present embodiment is formed at the lower end of the partition wall 15, the raw water input port 17 is formed above the side wall 21b. That is, the communication port 19 is provided at a position farthest from the raw water supply port 17 in the linear direction even in the z-axis direction. In other words, the communication port 19 of the partition wall 15 is provided at a position farthest from the raw water input port 17.

If the raw water inlet 17 cannot be provided at the above position due to interference with other components, etc., this is not the case. That is, the raw water input port 17 may be provided at a position separated from the communication port 19 by a linear distance as much as possible. Moreover, although the raw | natural water inlet 17 of this embodiment is formed in the side wall 21b orthogonal to the partition 15, it is not restricted to this, The side wall 21a arrange | positioned so that it may be parallel to the partition 15 and a straight line You may form in the upper surface 22 of the anaerobic process area | region A1 used as a position as far as possible by distance.
It is desirable that the discharge pipe 10 be located as far as possible from the communication port 19 by a linear distance.

The reaction tank body 13 is formed with a circulating liquid inlet 18 which is an outlet of the circulation line 12. That is, the circulating liquid R that is a part of the water to be treated W2 discharged from the reaction tank 3 is input to the reaction tank 3 from the circulating liquid input port 18.
The circulating fluid inlet 18 is provided in the vicinity of the raw water inlet 17. The raw water inlet 17 and the circulating fluid inlet 18 are arranged as close as possible. Similar to the raw water input port 17, the circulating fluid input port 18 is provided at a position farthest from the communication port 19 by a linear distance or as far as possible.

  The first agitation tank 4 is a tank for removing nitrite nitrogen and nitrate nitrogen that cannot be treated in the reaction tank 3 and remain. The first stirring tank 4 has a stirring device (not shown). The first agitation tank 4 is supplied with raw water of the treated water W <b> 1 through the second raw water supply pipe 16.

The aeration tank 5 is a tank that nitrifies ammoniacal nitrogen and organic nitrogen contained in the water to be treated W3 discharged from the first stirring tank 4 with nitrifying bacteria in an aerobic atmosphere.
Similar to the first stirring tank 4, the second stirring tank 6 is a tank for removing nitric acid. The second stirring tank 6 has a stirring device (not shown) and a methanol addition line 20 for adding methanol as an organic carbon source to the second stirring tank 6.

The sludge separation tank 8 is a precipitation tank that separates solids such as sludge contained in the water to be treated W6 by precipitation separation or the like.
A part of the excess sludge S2 separated in the sludge separation tank 8 is sent as an excess sludge S4 to, for example, equipment for performing sludge dehydration, drying, incineration, composting, and the like. The remainder of the excess sludge S2 is returned to the reaction tank 3 via the return line 11 as return sludge S3.

Next, the operation of the nitrogen removing apparatus 1 of the present embodiment will be described.
When the partition wall 15 is provided in the reaction tank 3 and the aeration apparatus 14 operates in the aerobic processing region A2, the oxidation-reduction potential (ORP) is positive in the aerobic processing region A2, and in the anaerobic processing region A1. Has a negative redox potential. That is, the internal region of the reaction tank 3 is divided into an aerobic treatment region A2 in an aerobic atmosphere and an anaerobic treatment region A1 in an anaerobic atmosphere.

  After the impurities contained in the human waste E and the septic tank sludge S1 are removed by the pretreatment device, they are introduced into the mixing tank 2 and homogenized. The homogenized water to be treated W1 is continuously fed into the anaerobic treatment region A1 and the first stirring tank 4 of the reaction tank 3 through the raw water supply pipe 9 and the second raw water supply pipe 16. The water to be treated W1 introduced into the reaction tank 3 flows into the aerobic treatment area A2 through the communication port 19.

  Ammonia nitrogen contained in the for-treatment water W1 is converted into nitrite nitrogen or nitrate nitrogen (nitric acid) by the action of nitric acid bacteria in the aerobic treatment region A2. Nitric acid circulates through the circulation line 12 as a circulating liquid R (nitrating liquid). In the anaerobic treatment region A1, the circulated circulating liquid R is reduced to nitrogen gas by using BOD (electron donor) of raw water by the action of denitrifying bacteria.

Denitrification and nitrification are also performed in the first treatment tank set 41 including the first stirring tank 4 and the aeration tank 5. In the first agitation tank 4, denitrification of the raw water of the water to be treated W <b> 1 supplied via the second raw water supply pipe 16 is performed, and in the aeration tank 5, the treatment target discharged from the first agitation tank 4 is performed. Nitrification of water W3 is performed.
Similarly, denitrification and nitrification are also performed in the second treatment tank set 42 including the second stirring tank 6 and the degassing tank 7.

  According to the said embodiment, the raw | natural water of the to-be-processed water W1 is divided | segmented into the raw | natural water supply pipe 9 and the 2nd raw water supply pipe 16, and flows into the reaction tank 3 and the 1st stirring tank 4. FIG. Thereby, the pollution load is made uniform and the efficiency of nitrogen removal can be improved. In other words, by removing nitrogen from the raw water of the water to be treated W1 in a shared manner by the reaction tank 3 and the first agitation tank 4, even when the capacity of the reaction tank 3 is small, nitrogen removal is surely performed. Can do.

  Further, by providing the methanol addition line 20 in the second agitation tank 6, nitrite / nitrate nitrogen components that have not been treated in the aeration tank 5 can be removed. Moreover, the methanol supplied from the methanol addition line 20 can be reduced by supplying the raw water of the to-be-processed water W1 to the 1st stirring tank 4. FIG.

  Further, the liquid phase part F of the reaction tank 3 is partitioned into an anaerobic treatment region A1 and an aerobic treatment region A2 by the partition wall 15, and a communication port 19 for communicating the anaerobic treatment region A1 and the aerobic treatment region A2 is a raw water. It is provided at a position as far as possible from the insertion port 17. Thereby, sufficient residence time required for denitrification of the to-be-processed water W1 supplied from the raw | natural water inlet 17 can be ensured. In other words, the water to be treated W1 introduced from the raw water inlet 17 can be prevented from flowing into the aerobic treatment region A2 without being denitrified, and more stable nitrogen removal can be achieved.

In addition, since the raw water inlet 17 and the circulating liquid inlet 18 are arranged close to each other, the BOD component contained in the water to be treated W1 and the nitrite / nitric nitrogen component contained in the circulating liquid R can be obtained. Since it contacts more, the efficiency of nitrogen removal can be improved.
A structure that improves the efficiency of nitrogen removal by stirring the inside of the tank (mechanical or gas-free stirring) may be used.

In addition, since the water to be treated W1 can be continuously supplied, it is not necessary to perform complicated intermittent water supply or precise aeration control.
Further, in the gas phase portion G of the reaction tank 3, the anaerobic treatment region A1 and the aerobic treatment region A2 communicate with each other, whereby the nitrogen gas exhaust line can be simplified. That is, it is not necessary to provide an exhaust line in each of the anaerobic processing region A1 and the aerobic processing region A2.

Further, by mixing the human waste E introduced into the reaction tank 3 and the septic tank sludge S1 in the mixing tank 2, the water to be treated W1 can be homogenized. Moreover, the fluctuation | variation of the property of the to-be-processed water W1 can be suppressed by mixing previously the septic tank sludge S1 whose property is unstable and the property is unstable in the mixing tank 2 with the urine E.
Moreover, by supplying the circulating liquid R to the aerobic treatment region A2 via the branch line 31, the water to be treated W1 in the aerobic treatment region A2 can be appropriately cooled.

In the above embodiment, the partition wall 15 is fixed to the reaction tank main body 13, but the present invention is not limited to this, and the partition wall 15 may be movable. Thereby, according to the property of the to-be-processed water W1, the capacity | capacitance of the aerobic process area | region A2 and the anaerobic process area | region A1 can be adjusted.
Further, the reaction tank 3 may be stirred (mechanical or oxygen-free gas stirring) to improve the nitrogen removal efficiency.
Moreover, in the said embodiment, although it was set as the structure set as aerobic atmosphere by providing the aeration apparatus 14 in the aerobic process area | region A2, it is not restricted to this, The structure set as aerobic atmosphere may be sufficient.

Next, a method for remodeling the nitrogen removing apparatus will be described.
The nitrogen removal apparatus 1 of the present embodiment has a reaction tank composed of a single tank, and a nitrogen removal apparatus (hereinafter referred to as a nitrification reaction and a denitrification reaction) in a single reaction tank by intermittently adding water to be treated. , Which is also referred to as an existing nitrogen removal device).
Specifically, the remodeling method of the nitrogen removing apparatus includes a reaction tank composed of a single tank, a raw water supply pipe for supplying water to be treated to the reaction tank, and raw water that is an outlet of the raw water supply pipe formed in the reaction tank. An inlet, a discharge pipe for discharging the water to be treated from the reaction tank, an anaerobic treatment tank that is provided downstream of the reaction tank and forms an anaerobic treatment area, and an aerobic treatment tank that forms an aerobic treatment area It can be manufactured by remodeling a nitrogen removing apparatus having a treatment tank set equal to or higher than the set and a circulation line for circulating the treated water from the discharge pipe to the reaction tank.

The remodeling method of a nitrogen removal apparatus includes the process of forming the partition similar to the nitrogen removal apparatus 1 of 1st embodiment in the reaction tank which does not have the existing partition. The partition wall is preferably formed in consideration of the position of the existing raw water inlet. That is, it is preferable to arrange the partition so that the communication port formed in the partition is as far as possible from the raw water inlet.
Moreover, the remodeling method of a nitrogen removal apparatus includes the process of moving the exit of a circulation line to the most upstream part of an anaerobic treatment area | region, and the process of adding the branch line which can adjust flow volume. In the step of moving to the most upstream part of the anaerobic treatment region, the circulating fluid inlet that is the outlet of the circulation channel and the raw water inlet are arranged close to each other.
It is preferable that the discharge pipe from the reaction tank (aerobic treatment region) is arranged as far as possible from the communication port.
In the case where a plurality of aeration apparatuses are arranged in the existing reaction tank, the aeration apparatus arranged in the anaerobic treatment region among the plurality of aeration apparatuses stops operation or is removed.

  Moreover, the remodeling method of a nitrogen removal apparatus includes the process of forming with the 2nd raw | natural water supply pipe | tube which supplies a part of to-be-processed water supplied from a raw | natural water supply pipe | tube to the anaerobic processing tank of a processing tank group. That is, it includes a step of forming a second raw water supply pipe branched from the raw water supply pipe and connected to at least one of the anaerobic treatment tanks of the treatment tank group.

Moreover, tanks, such as an existing preliminary storage tank, can be diverted as a mixing tank. As shown in FIG. 3, when the existing nitrogen removing device introduces urine E and septic tank sludge S1 through the pretreatment device 25 and the storage tank 26, the existing preliminary storage tank is used as the mixing tank 2. A line 27 for connecting the pretreatment device 25 and the mixing tank 2 and the raw water supply pipe 9 may be newly provided. After the transfer pipe 29 is provided and transferred to the storage tank 26, the existing raw water supply pipe may be used.
When there is no suitable tank for the mixing tank 2, etc., as shown in FIG. 4, the existing storage tanks 26 are connected to each other via a connecting pipe 28, and the human waste E and the septic tank sludge S1 are mixed in advance. Also good.

  According to the remodeling method of the nitrogen removing apparatus, the existing nitrogen removing apparatus can be diverted to be a nitrogen removing apparatus that can secure a sufficient residence time required for denitrification of water to be treated.

Next, conditions for carrying out the remodeling method of the nitrogen removing apparatus will be described.
The remodeling of the nitrogen removing device is preferably carried out when any one of the following four conditions is satisfied.
The first condition is when the BOD / TN ratio of the raw water to be treated is 3 or less. In other words, this is a case where the raw water to be treated has undesirable properties for denitrification.
The second condition is a case where TN of the treated water T to be discharged becomes difficult to satisfy the regulation value. In other words, this is a case where the performance of the nitrogen removing device no longer satisfies the requirements.
The third condition is when the ammonia concentration at the inlet of the stirring tank, that is, at the outlet of the reaction tank exceeds the discharge standard value.
The fourth condition is a case where the total nitrogen amount of the raw water to be treated exceeds the total nitrogen-MLSS load 0.05 kg-N / kg-MLSS · day.

  By setting the above conditions, the user of the existing nitrogen removal apparatus can accurately determine whether or not to modify.

(Second embodiment)
Hereinafter, the nitrogen removal apparatus 1B of 2nd embodiment of this invention is demonstrated based on drawing. In the present embodiment, differences from the first embodiment described above will be mainly described, and description of similar parts will be omitted.
As shown in FIG. 5, the nitrogen removing apparatus 1B of the present embodiment has a circulation line 12B as an alternative to the circulation line 12 of the first embodiment. The circulation line 12B is a circulation channel that circulates the treated water W4 as the circulating liquid R from the aeration tank 5 that is an aerobic treatment region to the uppermost stream portion of the anaerobic treatment region A1.
That is, the circulating liquid R containing nitrite and nitrate nitrogen is not limited to the aerobic treatment region A2 of the reaction tank 3, but may be circulated from other aerobic treatment regions such as the aeration tank 5 and the deaeration tank 7. . In other words, the circulating liquid R may be circulated from at least one aerobic treatment region of the reaction vessel 3 and the treatment vessel group to the most upstream part of the anaerobic treatment region.

(Third embodiment)
Hereinafter, the nitrogen removal apparatus 1B of 3rd embodiment of this invention is demonstrated based on drawing. In the present embodiment, differences from the first embodiment described above will be mainly described, and description of similar parts will be omitted.

As shown in FIG. 6, the communication port 19B of the partition wall 15B of the reaction tank 3B of the present embodiment is provided near the center in the vertical direction of the partition wall 15B. The raw water inlet 17 and the circulating fluid inlet 18 are provided near the lower end of the side wall 21.
Here, the communication port 19B needs to be provided in a region near the center in the vertical direction of the partition wall 15 from the lower end of the partition wall 15B. This is because when the communication port 19 is provided in the vicinity of the upper end of the partition wall 15B, the water to be treated W1 in the aerobic treatment area A2 is caused by the upward flow of the water to be treated W1 generated by the aeration apparatus 14. It is because it becomes easy to flow. Therefore, when the raw water inlet 17 and the circulating fluid inlet 18 are provided in the lower part of the reaction tank 3B, the communication port 19B is formed near the center in the vertical direction without being formed above the partition wall 15B.

  That is, when the raw water inlet 17 and the circulating fluid inlet 18 are provided in the vicinity of the lower end of the side wall 21, the communication hole 19B formed in the partition wall 15B is preferably provided in the vicinity of the center in the vertical direction. Further, it is desirable that the discharge pipe 10 be located as far as possible from the communication port 19 by a linear distance.

  The embodiments of the present invention have been described in detail with reference to the drawings. However, the configurations and combinations of the embodiments in the embodiments are examples, and the addition and the omission of the configurations are within the scope not departing from the gist of the present invention. , Substitutions, and other changes are possible. Further, the present invention is not limited by the embodiments, and is limited only by the scope of the claims.

DESCRIPTION OF SYMBOLS 1,1B Nitrogen removal apparatus 2 Mixing tank 3,3B Reaction tank 4 1st stirring tank 5 Aeration tank 6 2nd stirring tank 7 Deaeration tank 8 Sludge separation tank 9 Raw water supply pipe 10 Discharge pipe 11 Return line 12 Circulation line 13 Reaction Tank body 14 Aeration device 15, 15B Bulkhead 16 Second raw water supply pipe 17 Raw water inlet 18 Circulating fluid inlet 19, 19B Communication port (opening)
20 Methanol addition line 21 Side wall 22 Upper surface 23 Bottom surface 25 Pretreatment device 26 Storage tank 27 Line 28 Connection pipe 29 Transfer pipe 31 Branch line 41 First treatment tank group 42 Second treatment tank group A1 Anaerobic treatment area A2 Aerobic treatment area C Clearance E Human waste F Liquid phase G Gas phase L Liquid level R Circulating fluid S1, S2, S3, S4 Sludge W1, W2, W3, W4 Water to be treated

Claims (3)

A reaction tank comprising a single tank having an aerobic treatment area and an anaerobic treatment area, and performing biological denitrification of water to be treated containing an organic nitrogen compound;
One or more treatment tank sets that are provided downstream of the reaction tank and are composed of an anaerobic treatment tank that forms an anaerobic treatment area and an aerobic treatment tank that forms an aerobic treatment area,
A raw water supply pipe provided at the upper part of the reaction tank to supply the treated water;
A partition partitioning the liquid phase part of the reaction vessel into the aerobic treatment region and the anaerobic treatment region;
A raw water inlet that is an outlet of the raw water supply pipe formed in the reaction tank;
A the raw water inlet from a position farthest Oite on a plane 及 beauty height Direction having a length and a width of the reactor on the partition wall, the provided in a part of the lower end of the partition wall A communication port for communicating the anaerobic treatment region and the aerobic treatment region;
A circulation passage for circulating the water to be treated from at least one of the aerobic treatment region to the most upstream part of the anaerobic treatment region of the reaction vessel and the treatment vessel group;
A nitrogen removal apparatus comprising: a second raw water supply pipe that supplies a part of the water to be treated supplied from the raw water supply pipe to the anaerobic treatment tank.   2. The raw water inlet and a circulating liquid inlet that is an outlet of the circulation channel are opened to the reaction tank, and the raw water inlet and the circulating liquid inlet are arranged close to each other. Nitrogen removal equipment. A reaction tank composed of a single tank that performs anaerobic treatment and aerobic treatment in biological denitrification of water to be treated containing an organic nitrogen compound;
One or more treatment tank sets that are provided downstream of the reaction tank and are composed of an anaerobic treatment tank that forms an anaerobic treatment area and an aerobic treatment tank that forms an aerobic treatment area,
A raw water supply pipe provided at the upper part of the reaction tank to supply the treated water;
A raw water inlet that is an outlet of the raw water supply pipe formed in the reaction tank;
A discharge pipe for discharging the treated water from the reaction tank;
A recirculation channel for circulating the water to be treated from the discharge pipe to the reaction tank,
A partition wall for partitioning the liquid phase portion of the reactor to the aerobic treatment region and the anaerobic treatment region, said on a plane 及 beauty height Direction having a length and a width of the reactor from the raw water inlet a Oite farthest, forming a partition wall having a communication port which is provided in a part of the lower end of the partition wall communicating with the aerobic treatment region and the anaerobic treatment region,
A step of forming a second raw water supply pipe for supplying a part of the treated water supplied from the raw water supply pipe to the anaerobic treatment tank; and
Moving the outlet of the circulation channel to the most upstream part of the anaerobic treatment region.

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