JPH11239799A - Method and device for removing nitrogen in organic material-containing water - Google Patents

Abstract

PROBLEM TO BE SOLVED: To efficiently and stably remove nitrogen in organic material-containing water when the water is biologically treated by a nitrification and endogenous denitrification method, by bringing a humic substance into contact with active sludge in an aerobic tank and in an oxygen-free tank. SOLUTION: A nitrified liquid generated in an aerobic tank 8 flows into an oxygen- free tank 8, wherein the oxygen-free tank 8 denitrifies the nitrified liquid by a biological treatment using a microorganism or the like. A denitrified sludge mixed liquor which has been denitrified in the oxygen-free tank 8 flows into a reaeration tank 12. In the reaeration tank 12, the denitrified sludge mixed liquor flown from the oxygen-free tank 8 is made to be an aerobic state to prevent the denitrified active sludge from rising to the surface of a sedimentation tank. Herein, a means for supplying a humic substance to the oxygen-free tank 6 and the aerobic tank is provided. As for the means for supplying the humic substance, when a powdery humic substance is used, a feeder or the like, which adds the humic substance as a powder or its suspension into the tanks, can be exemplified. When a pellet-like humic substance is used, a means which puts the pellets of the humic substance in a wire net basket or the like and immerses them into water in the tanks can be exemplified.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and an apparatus for removing biological nitrogen from water containing organic matter such as wastewater, and more particularly to a method for efficiently and stably removing nitrogen contained in sewage and food wastewater. Related to the device.

[0002]

2. Description of the Related Art As a method for removing nitrogen content in water containing organic substances, a nitrification and denitrification method utilizing a living organism is mainly employed. One of the typical techniques is a nitrification and endogenous denitrification method.

In the nitrification and endogenous denitrification method, the first stage is an aerobic tank,
The third stage consists of an anoxic tank, the third stage a re-aeration tank, and the fourth stage a sedimentation tank. In this method, nitrification is first performed in an aerobic tank. In the anoxic tank, no organic matter is added, and the organic matter contained in the wastewater or the like adsorbed by the activated sludge in the first nitrification step and the organic matter accumulated in the cells of the activated sludge are used as the organic matter source for the denitrification reaction. . In the re-aeration tank, the mixed liquid flowing from the oxygen-free tank is brought into an aerobic state, and the floating of activated sludge by denitrification in the subsequent settling tank is prevented.

[0004] This method is characterized in that a circulating pump is not required because the nitrification liquid is not circulated, and a relatively high nitrogen removal rate can be obtained. However, when the object of denitrification treatment is sewage, nitrogen removal is considered. More than twice the residence time and tank volume are required compared to the standard activated sludge method, which is not performed.

More specifically, when using a standard activated sludge method that does not consider nitrogen removal in treating municipal sewage,
The nitrogen removal rate is about 30%, and the residence time is 6 to 8 hours. When nitrogen is removed by nitrification and endogenous denitrification, a nitrogen removal rate of 70 to 90% is obtained, but the residence time is 18 to 90%.
25 hours are required, which requires large-scale processing equipment.

[0006]

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances.
An object of the present invention is to solve the problems of the endogenous denitrification method and to provide a method and an apparatus capable of efficiently and stably removing nitrogen from organic substance-containing water.

[0007]

To achieve the above object, the present invention provides (1) an organic substance containing a nitrogen compound by a biological treatment step using an aerobic tank, an anoxic tank, a re-aeration tank, and a sedimentation tank in this order. A method for removing nitrogen from organic matter-containing water by a nitrification and endogenous denitrification method for biologically treating the water containing the organic matter, wherein the humic substances and the activated sludge are brought into contact in the aerobic tank and / or the oxygen-free tank. A method for removing nitrogen from water, and (2) a nitrification and endogenous denitrification method for biologically treating organic-containing water containing nitrogen compounds by a biological treatment step using an aerobic tank, an oxygen-free tank, a re-aeration tank, and a sedimentation tank in this order. In the method for removing nitrogen from organic substance-containing water by the method described above, a part of the activated sludge generated in the biological treatment step is sent to a contact tank in which humic substances are immersed to bring the humic substances into contact with the activated sludge and the activated sludge contacted with the humic substances Before The present invention proposes a method for removing nitrogen from organic substance-containing water, which is returned to an aerobic tank, an anoxic tank, or a re-aeration tank in a biological treatment step. (3) In the above (1) and (2), This includes the case where the humic substance is a substance mainly composed of humic substances and siliceous substances.

The present invention also provides (4) an aerobic tank for receiving an organic substance-containing water containing a nitrogen compound and performing a nitrifying biological treatment, and a non-aeration tank for receiving a nitrifying liquid generated in the aerobic tank and performing a denitrifying biological treatment. An oxygen tank, at least a re-aeration tank that receives the denitrification sludge mixed liquid in the anoxic tank and makes it aerobic, and a sedimentation tank that sediments and separates the liquid from the re-aeration tank into treated water and activated sludge. The apparatus for removing nitrogen from organic substance-containing water, wherein the aerobic tank and / or the anoxic tank comprises means for supplying humic substances. An aerobic tank for receiving the organic matter-containing water and performing the nitrification biological treatment, an anoxic tank for receiving the nitrification liquid generated in the aerobic tank and performing the denitrification biological treatment, and a denitrification sludge mixed liquid in the anoxic tank Re-exposure to accept aerobic conditions Tank, a sedimentation tank for sedimenting and separating the liquid from the re-aeration tank into treated water and activated sludge, and receiving a part of the activated sludge in the sedimentation tank to bring the humic substances and a part of the activated sludge into contact with each other A nitrogen removing apparatus for removing organic matter-containing water, comprising at least a contact tank for returning the contacted activated sludge to the aerobic tank. Is a substance mainly composed of humic substances and siliceous substances.

In the present invention, in the nitrification and endogenous denitrification method comprising an aerobic tank, an anoxic tank, a re-aeration tank, and a sedimentation tank, the aerobic tank and / or Alternatively, humic substances are added and / or immersed in an anoxic tank, and the humic substances and the activated sludge slurry are brought into contact with each other to promote the biological activity of the activated sludge microorganisms by the components of the humic substances to promote the growth of nitrifying bacteria and denitrifying bacteria. Thus, nitrogen is efficiently and stably removed.

[0010] In addition, the contact between the humic substances and the activated sludge slurry also has the effect of improving the sludge sedimentation property, which greatly contributes to the stability of the treatment. A contact tank is provided separately from the biological treatment step. After the humic substances are immersed in the contact tank and the concentrated activated sludge slurry precipitated and separated from the humic substances is contacted, the activated sludge slurry is returned to the biological treatment step. You can also. In this case, the number of tanks increases, but the contact between the humic substances and the activated sludge microorganisms can be increased, so that the nitrogen removal treatment can be performed more efficiently.

Hereinafter, the present invention will be described in detail with reference to the drawings.

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a schematic diagram showing an example of a configuration of an apparatus for removing nitrogen from organic substance-containing water according to the present invention.

Food wastewater from city sewage, kitchens, food factories, etc.
And other organic matter-containing water (raw water) containing nitrogen compounds 2
Flows through the inflow pipe 4 into the first-stage aerobic tank 6.

The aerobic tank 6 performs a biological treatment in an aerated state to convert nitrogen compounds contained in raw water into NO ₃ ⁻ ,
NO ₂ ^- is to nitrification enriched liquid. The stirring in the aerobic tank 6 is preferably aeration stirring.

The nitrification liquid generated in the aerobic tank 6 flows into the anoxic tank 8 through a first connecting pipe 10 connecting the aerobic tank 6 and the second-stage anoxic tank 8. The anoxic tank 8
It serves to receive the nitrification liquid generated in the first-stage aerobic tank 6 and denitrify it by biological treatment using microorganisms or the like. Since the inside of the oxygen-free tank 8 is not ventilated, the stirring is preferably performed by a mechanical stirring device or a pump stirring device.

The denitrified sludge mixed solution denitrified in the anoxic tank 8 then passes through a second connecting pipe 14 connecting the anoxic tank 8 and the re-aeration tank 12 to the third-stage re-aeration tank 12. Inflow.
In the re-aeration tank 12, the denitrification sludge mixture flowing from the anoxic tank 8 is brought into an aerobic state, and the floating of the denitrification activated sludge in the four-stage settling tank 16 described later is prevented.

The re-aeration tank 12 and the subsequent settling device 16 are connected by a third connecting pipe 18.
, The sludge slurry in the re-aeration tank 12 flows into the settling tank 16, where the sludge slurry is separated into sludge and treated water. The separated treated water flows out of the apparatus through a treated water outflow pipe 20 connected to the settling tank 16.

A sludge take-out pipe 22 is connected to the sedimentation tank 16, and a part of the sludge separated in the sedimentation tank 16 is taken out of the apparatus as excess sludge through the sludge take-out pipe 22. . The amount of excess sludge to be taken out is a matter appropriately selected by a person skilled in the art by a conventional method in consideration of the nitrogen compound concentration and other conditions.

A sludge return pipe 24 has one end connected to the sludge take-out pipe 22 and the other end connected to the inflow pipe 4, and the sludge separated in the sedimentation tank 16 through the sludge return pipe 24. Among them, sludge other than the sludge taken out as surplus sludge is returned to the upstream side of the first-stage aerobic tank 6.

In this embodiment, in addition to the above configuration, a means (not shown) for supplying humic substances to the aerobic tank 6 and / or the anoxic tank 8 is further provided.

The means for supplying the humic substances is not particularly limited, but when the humic substances are in the form of powder, a feeder for adding the powder or a suspension thereof to the tank can be exemplified. When the humic substances are formed into pellets, as a means for supplying the humic substances, a wire mesh basket, a plastic mesh bag, a basket made of perforated metal, or the like is preferable. Means for putting the pellets and immersing them under the water surface of the aerobic tank 6 and / or the anoxic tank 8 can be exemplified. Specifically, it can be immersed by hanging it under the water surface or installing it away from the bottom of the tank, whereby the activated sludge and the humic substances can be brought into sufficient contact.

The humic substances to be used in the present invention may be selected from the group consisting of "a metabolite containing phenol or / and a compound having a phenol-exposed group, or a metabolite described in JP-B-5-66199, column 6, lines 27-9. Substances to be contained (for example, humic substances) ”and the like. This humic substance may be a commercially available humic substance, such as a humic substance pellet MG-000 manufactured by Aoki Electric Industry Co., Ltd.
1, MG-0002 and humic powder include a mixture of MT-0001 powder and siliceous powder manufactured by the company.

The description related to humic substances and the like is also described in detail in Kyoichi Kumada, "Chemistry of Soil Organic Matter", pp. 1 to 7, published by Gakkai Shuppan Center.

The humic substance is powder or 15 to 20 m in diameter.
m, a molded pellet having a length of about 30 to 50 mm is preferable. When adding humic substances to an anoxic tank or an aerobic tank,
Powdery humic substances are suitable and the effect is immediate. The pelleted humic substances are suitable when immersed in the aerobic tank 6 and / or the anoxic tank 8, and the effect is continuous.

The contact between the pellets and the activated sludge slurry is generally performed by aeration and agitation in the aerobic tank 6 and by mechanical agitation and pump agitation in the anoxic tank 8.

Next, referring to FIG. 2, an example of the configuration of the device of the present invention, which is different from the above, will be described.

In the configuration example of FIG. 2, the aerobic tank 6 and / or the anoxic tank 8 are not provided with a means for supplying humic substances, but are provided with an independent contact tank 26 instead.

The contact tank 26 contains humic substances therein and has a stirring device. The humic substances are preferably in the form of pellets, and it is desirable to fill the basket with the humic substances in the form of pellets as described above, and to store this in the contact tank 26.

The stirring in the contact tank 26 may be any of mechanical stirring, pump stirring, ventilation stirring, and air lift stirring.

An inlet pipe 28 connects the sludge return pipe 24 and the contact tank 26. 30 is an outlet pipe,
The contact tank 26 and the aerobic tank 6 are connected. Then, a part of the sludge separated in the sedimentation tank 16 passes through the inlet pipe 28 and enters the contact tank 26, where the sludge and the humic substances are sufficiently stirred and contacted. 6.

In this embodiment, except for the configuration described above,
Since the configuration is the same as that shown in FIG. 1, the same portions are denoted by the same reference numerals and description thereof will be omitted.

Hereinafter, the present invention will be described more specifically with reference to examples.

[0033]

(Example 1) A removal apparatus of the present invention having the processing flow shown in FIG. 1 was manufactured, and a test for removing nitrogen from sewage was performed.
The humic substances are humic pellets (MG-0) of Aoki Electric Industry Co., Ltd.
A 1: 1 (weight ratio) mixture of 001 and MG-0002) and a humus powder (1: 1 (weight ratio) mixture of MT-0001 and siliceous powder) were used. The humus pellets were immersed in the aerobic tank 6 in a metal basket, and the humus powder was added to the anoxic tank 8.

(Comparative Example 1) The procedure was performed under the same conditions as in Example 1 except that no humic substances were used.

(Comparative Example 2) The residence time was doubled,
The procedure was performed under the same conditions as in Example 1 except that no humic substances were used.

The average sewage quality used was as follows. pH: 7.2 BOD: 145 mg / L COD: 72 mg / L SS: 69 mg / L T-N: 43 mg / L NH 4 -N: a 32 mg / L treatment conditions shown in Table 1.

[0037]

[Table 1] Sludge return ratio = sludge return amount × 100 / sewage treatment amount.

The average treated water quality and sludge settling (SVI) for 1.5 months after 2 weeks are as shown in Table 2.
The removal of BOD, COD and SS was almost the same in Example 1, Comparative Example 1 and Comparative Example 2. On the other hand, the nitrogen removal rate was as high as 85% in Example 1. However, in the case of Comparative Example 1 in which humic substances were not used under the same treatment conditions, the nitrogen removal rate was only 60%. Comparative Example 2 in which the residence time was doubled
In this case, the nitrogen removal rate was 82%, a value close to that of Example 1. Example 1 has the lowest sludge settling property (SVI),
Stable processing could be performed.

[0039]

[Table 2] NO _X -N indicates the total amount of nitrate nitrogen and nitrite nitrogen.

The number of nitrifying bacteria and the number of denitrifying bacteria in Examples and Comparative Examples after one month have been measured, and are shown in Table 3. Nitrite and nitrate are counted by latex agglutination using antibodies,
Denitrifying bacteria were counted by the most probable number method using a Giltay medium.

In the case of Example 1, the numbers of nitrites, nitrites and denitrifiers were all higher than those of Comparative Examples 1 and 2, and the use of humic substances promoted the growth of these bacteria, and as a result, the number was shorter. It was clear that a high nitrogen removal rate was obtained at the residence time.

[0042]

[Table 3] (Example 2) A nitrogen removal apparatus of the present invention having the treatment flow shown in FIG. 2 was manufactured, and a treatment test was performed using H food wastewater as raw water. Humic pellets (mixture of MG-0001 and MG-0002 at a ratio of 1: 3 (weight ratio)) of Aoki Denki Kogyo Co., Ltd. were used as the humic substances, which were immersed in a contact net in a plastic mesh bag. .

(Comparative Example 3) The same procedure as in Example 2 was carried out except that no humic substances were used.

(Comparative Example 4) The residence time was doubled,
The treatment was carried out under the same conditions as in Example 2 except that no humic substances were used.

The average quality of the raw water was as follows. pH: 5.4 BOD: 960 mg / L COD: 570 mg / L SS: 105 mg / L T-N: 155 mg / L NH 4 -N: a 38 mg / L treatment conditions shown in Table 4. The aerobic tank, anoxic tank, re-aeration tank, and sedimentation tank used had the same volumes as in Example 1.

[0046]

[Table 4] The average treated water quality and sludge settling property (SVI) for 1.5 months after 2 weeks were as shown in Table 5.

The removal of BOD, COD and SS is described in Example 2,
Comparative Examples 3 and 4 were almost the same.

On the other hand, the nitrogen removal rate of Example 2 was as high as 91%. However, in Comparative Example 3 under the same treatment conditions except that no humic substances were used, the nitrogen removal rate was 54%.
% Was low. Comparative Example 4 in which the residence time was doubled
Had a nitrogen removal rate of 85%. Sludge sedimentation (SV
As for (I), Example 2 was the lowest, and stable processing could be performed.

[0049]

[Table 5] (Example 3) In accordance with the processing flow shown in FIG. 1, a verification test was performed using a nitrogen removal apparatus of the present invention manufactured on a large scale for sewage. Aoki Denki Kogyo for humic substances
Humus pellets (MG-0001 and MG-0002)
And a humus powder (MT-00).
01 and a 1: 2 (weight ratio) mixture of siliceous powder). The humus pellets were placed in a wire mesh basket and immersed in an anoxic tank. The humus powder was added to the aerobic tank using a feeder.

The average water quality of the sewage was as follows. pH: 7.0 BOD: 121 mg / L COD: 59 mg / L SS: 33 mg / L TN: 42 mg / L NH ₄ -N: 28 mg / L The processing conditions are shown in Table 6.

[0051]

[Table 6] The average treated water quality and sludge sedimentability for two months after one month have passed are as shown below. A higher nitrogen removal rate was achieved with a shorter residence time than the ordinary method, and a stable and efficient desorption was achieved with a low SVI. Nitrogen treatment could be continued. pH: 7.3 BOD: 2.2 mg / L COD: 8.7 mg / L SS: 5.6 mg / L T-N: 5.9 mg / L NH ₄ -N: 0.4 mg / L _{NO X -N: 4.1 mg / L} T-N removal ratio: 86%

[0052]

According to the present invention, humic substances are used in the nitrification and endogenous denitrification method for biologically removing nitrogen compounds in water containing organic substances, so that the humic substances are equivalent to or longer than the conventional method with a shorter residence time. Denitrification treatment is possible. For this reason, it is not necessary to add a large-scale removal device, and it is possible to stably remove nitrogen with the minimum device without deteriorating the quality of the treated water. In addition, not only nitrogen removal, nitrification and endogenous denitrification combined with coagulant
It is equally effective for removing nitrogen and phosphorus by endogenous denitrification.

[Brief description of the drawings]

FIG. 1 is a flowchart showing an example of the nitrogen removal method of the present invention.

FIG. 2 is a flowchart showing another example of the nitrogen removing method of the present invention.

[Explanation of symbols]

 2 raw water 4 inflow pipe 6 aerobic tank 8 anoxic tank 12 re-aeration tank 16 sedimentation tank 20 treated water outlet pipe 26 contact tank

Continuation of the front page (71) Applicant 598032483 TNB Corporation 3-1-1-20 Matsuda, Higashi-ku, Fukuoka City, Fukuoka Prefecture (72) Inventor Yasuhiro Kurokawa 42-10 Oharadai, Yokosuka City, Kanagawa Prefecture (72) Inventor Machiguchi Koji 19-32, Shirahama-cho, Minamata-shi, Kumamoto (72) Inventor Tatsuhisa Mitoma 1-40-606 Mishimazaki, Higashi-ku, Fukuoka-shi, Fukuoka (72) Inventor ▲ Hama ▼ ▲ Saki ▼ Yoshihide Nishitozaki, Higashi-ku, Fukuoka-shi, Fukuoka 3-2-27 (72) Inventor Sueo Otani 1801, Beppu, Odai, Shimen-cho, Kasuya-gun, Fukuoka

Claims (6)

[Claims] 1. An organic matter-containing water by a nitrification / endogenous denitrification method in which an organic matter-containing water containing a nitrogen compound is biologically treated by a biological treatment step used in the order of an aerobic tank, an anoxic tank, a re-aeration tank, and a sedimentation tank. In the nitrogen removal method, the aerobic tank and / or
Alternatively, a method for removing nitrogen from organic matter-containing water, comprising contacting humic substances with activated sludge in an oxygen-free tank. 2. An organic matter-containing water by a nitrification and endogenous denitrification method in which an organic matter-containing water containing a nitrogen compound is biologically treated by a biological treatment step used in the order of an aerobic tank, an anoxic tank, a re-aeration tank, and a sedimentation tank. In the nitrogen removal method, a part of the activated sludge generated in the biological treatment step is sent to a contact tank in which humic substances are immersed to contact the humic substances with the activated sludge, and the contacted activated sludge is subjected to the biological treatment step. A method for removing nitrogen from organic substance-containing water, wherein the method is returned to an aerobic tank, an anoxic tank, or a re-aeration tank. 3. The method for removing nitrogen from organic matter-containing water according to claim 1, wherein the humic substance is a substance containing humic substances and siliceous substances as main components. 4. An aerobic tank for receiving an organic substance-containing water containing a nitrogen compound and performing a nitrification biological treatment, an oxygen-free tank for receiving a nitrification liquid generated in the aerobic tank and performing a denitrification biological treatment, and Nitrogen removal from organic matter-containing water having at least a re-aeration tank for receiving a denitrification sludge mixed liquid in an oxygen tank to make it aerobic, and a sedimentation tank for sedimenting and separating the liquid from the re-aeration tank into treated water and activated sludge The apparatus for removing nitrogen from organic substance-containing water, wherein the aerobic tank and / or the anoxic tank comprises means for supplying humic substances. 5. An aerobic tank for receiving an organic substance-containing water containing a nitrogen compound and performing a nitrification biological treatment, an oxygen-free tank for receiving a nitrification solution generated in the aerobic tank and performing a denitrification biological treatment, and A re-aeration tank for receiving the denitrification sludge mixed solution in the oxygen tank to make it aerobic, a sedimentation tank for sedimenting the liquid from the re-aeration tank into treated water and activated sludge, and an activated sludge in the sedimentation tank. And a contact tank for receiving the humic substances and contacting the activated sludge with a part of the activated sludge, and returning the contacted activated sludge to the aerobic tank. . 6. The apparatus for removing nitrogen from organic substance-containing water according to claim 4, wherein the humic substance is a substance containing humic substances and siliceous substances as main components.