JP2000070987A - Method and apparatus for removing phosphorus in waste water - Google Patents

Abstract

PROBLEM TO BE SOLVED: To effectively and inexpensively prevent the deterioration of phosphorus removing performance while compensating the shortage of the organic material concentration in the waste water and effectively utilizing a produced organic material by crushing or grinding at least a part of deposits in a sedimentation basin for the waste water to be treated and supplying them to an anaerobic vessel. SOLUTION: The waste water 1 is fed to the anaerobic vessel 3 and an aerobic vessel 4 through solid-liquid separation in an initial sedimentation basin 2 and is separated into treated water 7 and activated sludge in a final sedimentation basin 6. The deposits 9 of the initial sedimentation basin 2 are crushed or ground by a crushing or grinding device 10 and sent to the anaerobic vessel 3 directly or through a flow-out water passage or the like. In the anaerobic vessel 3, phosphate ion accumulated in the activated sludge cells is released in the waste water by utilizing the organic material originating from the initial sedimentation basin deposit 9. In the aerobic vessel 4, the activated sludge assimilates the phosphate ion in the waste water in the activated sludge cells to carry out the oxidation decomposition and the removal of the organic material. Thus the method is effectively and rapidly utilized for the phosphorus releasing and the phosphorus assimilation reaction.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention generally belongs to the field of sewage and wastewater treatment, and more particularly to a method and an apparatus for removing phosphorus from wastewater.

[0002]

2. Description of the Related Art There is an activated sludge process as a conventional representative treatment process for removing organic substances from wastewater, and an anaerobic aerobic activated sludge process is a conventional method for simultaneously removing phosphate ions and organic substances. There is.

FIG. 6 shows an example of a wastewater treatment apparatus using the anaerobic-aerobic activated sludge method. The wastewater treatment apparatus using the anaerobic and aerobic activated sludge method comprises an initial settling basin 2, an anaerobic tank 3 in which activated sludge releases intracellular phosphate ions into wastewater by a biological phosphorus release reaction, and a biological phosphorus intake. The activated sludge is constituted by an aerobic tank 4 for ingesting phosphate ions in wastewater into cells by a reaction and a final sedimentation basin 6. The phosphorus intake of the activated sludge in the aerobic step is larger than the phosphorus release in the anaerobic step, and the difference between the phosphorus intake and the phosphorus release corresponds to the phosphorus removal from the wastewater.

After first removing relatively large and heavy solids contained in wastewater 1 in a sedimentation basin 2, a biological phosphorus release reaction in an anaerobic process and a biological phosphorus uptake reaction in an aerobic process are performed. The phosphorus in the wastewater is converted into a constituent component of the sludge, and is finally discharged from the wastewater treatment apparatus as surplus sludge. Organic matter in the wastewater is removed in both the anaerobic step and the aerobic step.

[0005] There are the following problems in removing phosphorus from wastewater using a wastewater treatment apparatus based on the anaerobic-aerobic activated sludge method. That is, when the organic matter concentration of the wastewater decreases due to the inflow of rainwater or the like, the wastewater is diluted while being supplied with oxygen. Therefore, the organic matter in the wastewater is supplied to the anaerobic process after being oxidized and diluted. As a result, the concentration of organic substances supplied to the anaerobic step is lower than the concentration of phosphate ions, so that the phosphorus release reaction rate in the anaerobic step and the phosphorus intake reaction rate in the aerobic step become lower, and the treated water is reduced. Water quality deteriorates.

Further, since solid pollutants of wastewater are settled and separated in the first sedimentation basin, the wastewater supplied to the anaerobic process via the first sedimentation basin is mainly composed of soluble pollutants. Accordingly, even when the organic matter concentration / phosphate ion concentration ratio of the soluble pollutants in the wastewater supplied to the anaerobic step is low, the phosphorus release reaction rate in the anaerobic step and the phosphorus intake reaction rate in the aerobic step are low. And the quality of the treated water deteriorates.

To cope with such a problem, an organic chemical such as methanol is supplied to the anaerobic step together with the wastewater to compensate for the shortage of the concentration of organic substances in the wastewater, thereby improving the phosphorus release reaction rate and the favorable rate in the anaerobic step. A method of preventing a decrease in the reaction rate of phosphorus intake in the pneumatic process has been used.

[0008] In the prior art in which organic chemicals are introduced into the anaerobic process, methanol, which is relatively inexpensive, is usually used, but the fact that chemicals are still expensive is a major problem with respect to operating costs. In addition, since methanol is a fourth-class hazardous substance, it must be handled in consideration of safety, and measures must be taken for storage facilities and facilities for receiving and supplying.

It is considered that sufficient organic substances are required in both the phosphorus release reaction in the anaerobic step and the phosphorus uptake reaction in the aerobic step, and the removal of organic substances from the wastewater by the anaerobic and aerobic activated sludge method is required. Insufficiently, good phosphorus removal results cannot be obtained, so the wastewater flowing into the sedimentation basin first contains organic matter that is first removed in the sedimentation basin, that is, the organic matter mainly composed of solid matter is subjected to the anaerobic process or The introduction into both the anaerobic step and the aerobic step is effective for improving the phosphorus removal treatment results.

[0010] As a conventional facility operation method having such an effect, the number of ponds used in the first sedimentation basin in the wastewater treatment facility having a plurality of treatment systems is reduced, and the operation of increasing the water area load on the first sedimentation basin is performed. Sedimentation basin effluent SS
And increasing the amount of organic matter flowing into the anaerobic process.

[0011]

However, it is difficult to accurately control the solid organic matter flowing into the anaerobic step by digital control of changing the number of first settling ponds.

[0012] In order to solve such a problem, the inventor of the present invention has proposed a technique capable of achieving a good phosphorus removal treatment by increasing the amount of organic substances supplied to an anaerobic tank. For removing phosphorus from wastewater, characterized by flowing the wastewater into an anaerobic tank, and a method for removing phosphorus from wastewater, comprising subjecting the sediment to ultrasonic treatment and flowing into the anaerobic tank (Japanese Patent Application No. Hei 9 (1994) -108). -1
No. 33989) and a method for removing phosphorus from wastewater characterized by subjecting the precipitate to ozone treatment and flowing into an anaerobic tank (Japanese Patent Application No. 9-133988). However, these methods have the following problems. When the sediment of the first sedimentation basin is directly introduced into the anaerobic tank, solid particles contained in the settling sludge are relatively large and have a small surface area per unit weight. Decomposition at
There is a problem that the processing speed is relatively small. In addition, when the precipitate in the sedimentation basin is first subjected to ultrasonic treatment and then introduced into the anaerobic tank, the solid, which is the precipitate, includes microorganisms and cellulose fibers wrapped in relatively hard cell walls or cell membranes. Since these are contained and are not easily destroyed by the vibration treatment using ultrasonic waves, there is a problem that the particle diameter of the solid introduced into the anaerobic tank does not become sufficiently small. Furthermore, when the sediment in the sedimentation basin is first subjected to ozone treatment and then introduced into the anaerobic tank, some of the organic matter contained in the sediment is oxidized and mineralized, losing its effectiveness as an organic matter, About 10-15 for ozone generation
Since a relatively large amount of power of kWh / kgO ₃ is consumed, there is a problem that the operation cost is relatively large.

The present invention has been made to solve the problem of deterioration of the phosphorus removal performance of an anaerobic aerobic activated sludge wastewater treatment apparatus caused by an insufficient concentration of organic substances in wastewater, particularly, a concentration of soluble organic substances. By supplying sludge containing solid organic substances generated in the sedimentation basin to the anaerobic tank and compensating for the lack of organic matter concentration in the wastewater flowing into the anaerobic tank, phosphorus can be effectively used in the wastewater treatment facility while effectively utilizing the organic substances generated in the wastewater treatment facility. It is an object of the present invention to provide a method and an apparatus capable of more effectively and economically performing a method for preventing the deterioration of the removal performance.

[0014]

SUMMARY OF THE INVENTION According to the present invention, at least phosphorus is removed from a wastewater to be treated by using an apparatus consisting of a sedimentation basin, an anaerobic tank and an aerobic tank. The present invention relates to a method and an apparatus for removing phosphorus from wastewater, which comprises crushing or grinding at least a part of the sediment in a sedimentation basin and supplying it to an anaerobic tank.

In the method and apparatus for removing biological phosphorus from wastewater according to the present invention, at least a part of the sediment of the first sedimentation basin rich in solid organic matter, that is, at least a part of the solid organic matter is fed into the anaerobic tank. In order to secure the concentration of organic substances required for the phosphorus release reaction in the anaerobic process,
Crushing or grinding at least a portion of the sediment in the first sedimentation basin so that the solid organic matter can be effectively and rapidly used by microorganisms for the phosphorus release reaction. The solid organic matter contained in the precipitate is made into fine particles or solubilized. Further, in the case where the organic matter concentration of the wastewater is low and the organic matter concentration required for performing the phosphorus release reaction in the anaerobic step cannot be secured, the present inventors have found that the oxidation-reduction potential (ORP) in the anaerobic step becomes -100 mV or more. According to the findings based on these experiments, the ORP in the anaerobic process was measured, and the ORP was -10.
Only when the value is 0 mV or more, that is, when the organic matter concentration required for performing the phosphorus release reaction in the anaerobic process is not secured, the sediment in the first sedimentation basin is subjected to crushing or grinding treatment. By flowing into an anaerobic tank and replenishing organic matter derived from solid matter, the concentration of organic matter necessary for the phosphorus release reaction is ensured.

[0016]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows an example of a biological phosphorus removal treatment apparatus according to the present invention. The present invention will be described in detail with reference to FIG.

As shown in FIG. 1, the biological phosphorus removal treatment apparatus according to the present invention mainly comprises a first sedimentation tank 2, an anaerobic tank 3, an aerobic tank 4, and a final sedimentation tank 6. In the anaerobic tank 3, only stirring is performed, and in the aerobic tank 4, oxygen is supplied by the diffusing device 5, and stirring is performed by a water flow generated by the diffusing.

In the biological phosphorus removal treatment apparatus according to the present invention shown in FIG. 1, waste water 1 is first passed through a sedimentation basin 2 through solid-liquid separation to an anaerobic tank 3 and an aerobic tank 4 sequentially. . The effluent flowing out of the anaerobic tank 4 and flowing into the final sedimentation basin 6 is separated into treated water 7 and activated sludge in the final sedimentation basin 6, and at least a part of the activated sludge separated and concentrated in the final sedimentation basin 6 is returned. The sludge 8 is sent to the anaerobic tank 3.

The first sedimentation tank sediment 9 is subjected to crushing treatment or grinding treatment by a crushing treatment device or attrition treatment device 10, and then directly anaerobic as the first sedimentation tank sedimentation 11 after the crushing treatment or the grinding treatment. Either sent to tank 3, sent to anaerobic tank 3 via the outflow channel of first settling basin 2, or removed the portion that settles again in first settling tank 2 via the inflow channel of first settling basin 2 First, it is sent to the anaerobic tank 3 via the outflow channel of the sedimentation basin 2.

In the anaerobic tank 3, the activated sludge utilizes the organic matter mainly composed of the soluble component in the wastewater 1 and the organic matter derived from the first sedimentation tank sediment 9 to remove phosphate ions accumulated in the activated sludge cells. Released into wastewater (= phosphorus release reaction). In the aerobic tank 4, the activated sludge ingests phosphate ions in the wastewater into the activated sludge cells (= phosphorus uptake reaction) and performs oxidative decomposition and removal of organic substances.

The solid organic matter contained in the first sedimentation tank sediment 9 is treated by a crushing treatment device or a grinding treatment device 10 so that at least a part thereof becomes fine particles and at least a part thereof becomes a soluble component. That is, when the particle diameter of the solid is reduced by the crushing or grinding treatment, the surface area of the solid having the same weight increases. In addition, the first sedimentation basin sediment 9 contains microorganisms, animals and plants, etc., and these organisms are composed of cells wrapped in cell membranes or cell walls, and these membrane-like structures are crushed. If the cells are destroyed by the treatment or the grinding treatment, the cell liquid is released out of the cells, so that the concentration of the soluble organic matter in the wastewater into which the first sedimentation basin sediment 11 after the crushing treatment or the grinding treatment is introduced increases. Becomes

In general, when a microorganism grows by decomposing and utilizing organic substances, it takes a longer time to complete the decomposition and utilization of a substance having a large molecular weight, and a substance having a small molecular weight is easily used and has a high reaction rate. It is. When organic matter is divided into solid organic matter and soluble organic matter, solid organic matter is generally harder to use for microorganisms because solid organic matter generally has a higher molecular weight. This is because when a microorganism takes in an organic substance into a microorganism via a cell membrane or a cell wall, the organic substance needs to have a sufficiently small molecular weight. It is considered that it takes a long time to decompose and use organic compounds, because a reaction of first decomposing organic substances having a large molecular weight into organic substances having a small molecular weight is required. In organisms, the reaction of decomposing high molecular weight organic substances into small molecular weight organic substances is mainly performed by enzymatic reactions.In such reactions, the more surfaces on which the enzyme acts, that is, the same weight of solid organic substances When the particle size is smaller, the reaction proceeds faster.
That is, in the method of the present invention, the crushing or grinding treatment is first performed on the sedimentation tank sediment 9 to reduce the particle diameter of the solid material, which means that the decomposition of the solid organic material by microorganisms
It assists in the progress of the enzymatic reaction for utilization, contributes to increasing the rate of decomposition and utilization of solid organic matter, and is effective for terminating the microbial reaction with a limited reactor volume. In addition, when soluble organic matter generated by subjecting the sedimentation tank sediment 9 to crushing or grinding treatment is also introduced into the anaerobic tank 3, the phosphorus release reaction and the denitrification reaction in the anaerobic tank 3 and the subsequent stage are performed. Is effectively and quickly used for the phosphorus uptake reaction in the aerobic tank 4 of the above-mentioned method. The organic matter contained in the solid matter in the wastewater 1 contributes to increasing the rate of decomposition and utilization by microorganisms in the reaction tank, and is effective for terminating the microbial reaction with a limited reaction tank volume.

When the crushed or crushed material of the first sedimentation basin sediment or the crushed material 11 that has been subjected to the crushing or grinding treatment is allowed to flow into the anaerobic tank 3, the crushed or crushed material 11 may be directly flowed into the anaerobic tank 3. It is possible to flow the crushed material or the crushed material 11 from the overflow weir of the sedimentation basin 2 to any point of the drainage flow path from the anaerobic tank 3. When such a method is used, the crushed or crushed material 11 of the sedimentation basin sediment can all flow into the anaerobic tank 3. Further, the capacity of the water channel from the supply point of the crushed material or the crushed material 11 to the anaerobic tank 3 is relatively small,
Since the residence time is relatively short, the supply amount of the crushed material or the crushed material 11 can be changed to influence the reaction in the anaerobic tank 3 in a relatively short time. In flowing the crushed material or the crushed material 11 into the anaerobic tank 3,
Either the crushed material or the crushed material 11 is allowed to flow directly into the anaerobic tank 3 or the crushed material or the crushed material 11 is first transferred to the anaerobic tank 3 from the overflow weir of the sedimentation basin 2. Is determined in consideration of the distance between the installation position of the crushing device or the crushing device 10 and the supply position of the crushed material or the crushed material 11 after the crushing process or the crushing process, the water head difference, and the like. can do.

The crushed material or the crushed material 11 is caused to flow into any point of the inflow channel of the first sedimentation basin 2 to separate and remove solids precipitated in the first sedimentation basin 2 again. It is also possible to allow the non-settling component of the crushed material 11 to flow into the anaerobic tank 3 together with the overflow water of the first settling tank 2. When such a method is used, all of the first sedimentation basin sediment 11 after the crushing treatment or the grinding treatment cannot flow into the anaerobic tank 3, but the anaerobic tank is supplied from the supply point of the crushed or crushed material 11. Since the capacity of the water channel leading to No. 3 is large and the residence time is long, components having a relatively stable concentration and excluding solids that easily settle and originate from the crushed material or the crushed material 11 flow into the anaerobic tank 3. Can be done.

Depending on conditions such as the concentration of phosphorus contained in the wastewater after the precipitation treatment by the first sedimentation basin 2 and the residence time in the anaerobic tank 3 and the aerobic tank 4, it is necessary to promote the phosphorus uptake reaction more than the phosphorus release reaction. Therefore, in such a case, the crushed material or the crushed material 11 can be introduced into the aerobic tank 4 together with the anaerobic tank 3.

The removal of the sediment 9 from the first sedimentation basin 2 can be performed by opening a discharge port provided at the lower part or the bottom of the first sedimentation basin 2. This is the first sedimentation basin 2
May be spontaneously discharged or a liquid feed pump may be used depending on the position of the liquid.

The sediment to be treated by the crusher or the attritor is suspended or slurry in the wastewater, and has a concentration of about 3000 to 12000 mg / l, usually about 5 mg / l.
It is about 000 to 10000 mg / l.

The addition time of the crushed material or the crushed material can be known, for example, by measuring the oxidation-reduction potential of an anaerobic tank, and the addition is performed when the potential becomes -100 mV or more. Further, when the ratio of the concentration of the organic matter to the concentration of the phosphate ion of the soluble pollutant in the wastewater 1 is almost always low, it is practical to always add the crushed material or the crushed material.

The pump used for pulling out the sediment 9 in the first sedimentation basin is usually a slurry pump in which clogging does not easily occur, and thus has little effect of crushing or grinding the sediment. Therefore, in order to crush or grind the precipitate, it is necessary to provide a crushing device or a grinding device. As the crushing device or the grinding device 10, various types such as a gear type and a multi-shaft disk type can be used. To control the degree of crushing or grinding,
It is effective to select the screen width of the screen to be passed after crushing or grinding, but if the screen width is too small, it is easy to clog, and if it is too large, solids with a large particle size tend to come out, The screen width of the screen is preferably about 1 to 5 mm. Further, the crushing device or the grinding device 10 can be installed in-line or in an open channel. However, considering that the sedimentation basin sediment 9 becomes a source of offensive odor, the in-line installation can be adopted. preferable. Such a crushing device or grinding device 1
The equipment cost is relatively inexpensive because a general-purpose commercial product can be applied as 1, and the operating cost, mainly the power cost of the motor, is relatively inexpensive, and the effect of reducing the particle size of solids is also compared. Big.

The added amount of the crushed material or the crushed material is about 0.1 to 1.5% with respect to the volume of the wastewater 1, usually 0.5 to 1.0%.
% Is appropriate. The addition may be continuous or intermittent.

When the addition is completed, the oxidation-reduction potential becomes -150 to-
It is appropriate that the temperature reaches about 250 mV. As a result, it is also effective to continue the addition at all times.

FIG. 2 shows another example of the biological phosphorus removal treatment apparatus according to the present invention. In the biological phosphorus removal treatment apparatus based on the prior art shown in FIG. 6, according to the experimental findings of the inventor, the dissolved organic matter concentration of the wastewater 1 is high, and the organic matter necessary for the phosphorus release reaction in the anaerobic tank 3. When the concentration is obtained, the ORP in the anaerobic tank 3 becomes -100 mV or less, the organic matter concentration of the wastewater 1 is low, and the organic matter of the concentration required for the phosphorus release reaction in the anaerobic tank 3 is not supplied. , The ORP in the anaerobic tank 3 becomes -100 mV or more. Based on these findings, in the biological phosphorus removal treatment apparatus according to the present invention shown in FIG.
When the measured value of the total 12 is about -150 to -250 mV or less, the flow of the first sedimentation tank sediment 11 into the anaerobic tank 3 after the crushing treatment or the grinding treatment is stopped, or a crushing treatment device or a grinding treatment is performed. An operation such as stopping the operation of the treatment apparatus 10 is performed, and when the measured value is −100 mV or more, the first sedimentation tank sediment 11 after the crushing treatment or the grinding treatment flows into the anaerobic tank 3. Control the operation of the device. These controls are performed by the control device 13.

The phosphorus removal method according to the present invention is applied not only to a wastewater treatment apparatus comprising an anaerobic step and an aerobic step but also to a wastewater treatment apparatus comprising an anaerobic step, a denitrification step (anoxic step) and a nitrification step (aerobic step). Can be applied.

FIG. 3 shows another example of the biological phosphorus removal treatment apparatus according to the present invention. The biological phosphorus removal treatment device according to the present invention shown in FIG. 3 is obtained by adding a denitrification tank 14 to the biological phosphorus removal treatment device according to the present invention shown in FIG. It comprises a pond 2, an anaerobic tank 3, a denitrification tank 14, an aerobic tank 4, and a final sedimentation tank 6.

In the biological phosphorus removal treatment apparatus according to the present invention shown in FIG. 3, the denitrification tank 14 is a tank in which only stirring is performed, and flows out of the anaerobic tank 3 into this tank and flows into the denitrification tank 14. The effluent and the nitrification circulating fluid 15 are sent. Denitrification tank 1
In No. 4, the nitrification circulating liquid 1 is utilized by utilizing the organic matter in the wastewater.
The nitrate nitrogen or nitrite nitrogen contained in 5 is reduced to nitrogen gas (= denitrification reaction) and denitrification treatment is performed.

In the biological phosphorus removal treatment apparatus according to the present invention shown in FIG. 3, a part of the crushed or ground material of the sedimentation basin sediment 11 may be flowed into the denitrification tank 14.

[0037]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the method for removing biological phosphorus according to the present invention will be described below. FIG. 4 shows an implementation device. In the present embodiment, a mixed solution of returned sludge, wastewater, and first sedimentation tank sediment collected from the wastewater treatment apparatus having the flow shown in FIG. 6 was put into the apparatus shown in FIG. 4 as a sample, and activated sludge under anaerobic tank conditions was used. The characteristics of the phosphorus release reaction of sucrose were investigated. Table 1 shows the composition of the sample. The BOD concentration of the wastewater collected from the wastewater treatment device having the flow shown in FIG. 6 was 42 mg / L, and the MLSS concentration of the returned sludge was 4200 mg / L. In order to check whether the wastewater treatment apparatus comprising the flow shown in FIG. 1 works effectively, the MLSS concentration 32 collected from the first sedimentation basin of the wastewater treatment facility according to the flow of FIG.
10m capacity for the first settling tank sediment of 00mg / L
An experimental study was conducted to determine whether a material subjected to a grinding treatment for 3 minutes with a 1 potter-type glass homogenizer was effective as an organic matter source.

[0038]

[Table 1]

FIG. 5 shows the change over time in the phosphate ion concentration in the sample wastewater. From these results, it was found that the sample A obtained when the phosphorus release reaction was performed under the condition where the first sedimentation tank sediment subjected to the grinding treatment was added.
And the sample B when the phosphorus release reaction was performed under the condition that the first sedimentation basin sediment was not added, the sedimentation of the first sedimentation basin sediment was subjected to the grinding treatment. When the phosphorus release reaction was carried out by adding, the rate of increase of phosphate ions in the wastewater was large. That is, the first sedimentation tank sediment is subjected to a grinding treatment to reduce the particle diameter of the solid matter and to solubilize some organic matter, and then is added to the sample wastewater, thereby adding phosphorus to the sample in the anaerobic step. The release reaction rate was found to be high.

The crushing process is also similar to the crushing process, and is considered to be effective in reducing the particle size of the solids in the sedimentation tank sediment and solubilizing some organic substances.

[0041]

According to the present invention, the first sedimentation basin sediment after crushing or grinding is subjected to an anaerobic step and, if necessary, to an anaerobic step of a biological phosphorus removing apparatus having an anoxic step and an aerobic step. It was made to flow in and to secure the organic matter concentration necessary for the phosphorus release reaction in the anaerobic step.

Thus, as in the case of rainwater inflow,
Even when the concentration of organic substances supplied to the anaerobic process is reduced to a level lower than the concentration of phosphate ions, the phosphorus release reaction rate in the anaerobic process is reduced and the quality of the treated water is deteriorated. The ratio of dissolved organic matter / phosphate concentration in the wastewater that flows into the anaerobic process after being subjected to solid-liquid separation in the anaerobic process is low, so the phosphorus release reaction rate in the anaerobic process is low and the quality of the treated water deteriorates In this case, since the supply of organic substances necessary for performing the phosphorus release reaction is ensured, it is possible to prevent a decrease in the rate of the phosphorus release reaction in the anaerobic step, and to perform the phosphorus release reaction in the subsequent aerobic step. It is also effective to increase speed.

Further, the ORP in the anaerobic step was measured, and the ORP was measured.
When the first sedimentation tank sediment after the crushing treatment or the attrition treatment is flowed into the anaerobic step only when the pressure is -100 mV or more, the organic matter concentration of the wastewater is reduced, and the phosphorus release reaction is performed in the anaerobic step. Organic substances can be replenished only when the necessary organic substance concentration is not ensured. With such a control, the power cost required to perform the crushing or grinding treatment on the first sedimentation tank sediment and the necessary cost to transfer the first sedimentation tank sediment after the crushing treatment or the grinding treatment to the anaerobic process Power costs can be minimized, and organic loads on the anaerobic and aerobic processes can be minimized.

The first sedimentation tank sediment is subjected to crushing or grinding treatment to reduce the particle size of the organic solids contained in the first sedimentation tank sediment and to partially solubilize it. By introducing it into the process, and in some cases further into the aerobic process or the denitrification process, it can be used quickly and effectively in a microbial reaction mainly comprising a phosphorus release reaction or a phosphorus uptake reaction.

Further, since a general-purpose product can be applied as an apparatus used for the crushing or grinding treatment, the equipment cost is economical, and the operation cost of the apparatus mainly including the power cost of the motor is relatively economical. The effect of breaking large solids is also great.

[Brief description of the drawings]

FIG. 1 is a diagram showing a configuration of a biological phosphorus removal treatment apparatus according to one embodiment of the present invention.

FIG. 2 is a view showing a configuration of a biological phosphorus removal treatment apparatus according to another embodiment of the present invention.

FIG. 3 is a view showing a configuration of a biological phosphorus removal treatment apparatus according to still another embodiment of the present invention.

FIG. 4 is a side view of a phosphorus release reaction experiment apparatus used in an example of the present invention.

FIG. 5 is a graph showing the change over time of the phosphate ion concentration with and without the addition of the ground material of the sediment in the first settling basin using the apparatus of FIG.

FIG. 6 is a side view showing a configuration of a conventional biological phosphorus removal treatment apparatus.

[Explanation of symbols]

 1. Wastewater 2. First sedimentation basin 3. Anaerobic tank 4. Aerobic tank 5. Air diffuser 6. Final sedimentation basin 7. Treated water 8. Return sludge 9. First sedimentation tank sediment 10. 10. Crushing device or grinding device Crushed or ground material of the first sedimentation tank sediment ORP meter 13. Control device 14. Denitrification tank 15. Nitrification circulating fluid 16. Stirrer 17. Beaker 18. sample

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Jun Miyata 1-2-1, Marunouchi, Chiyoda-ku, Tokyo Japan Inside the Kokan Kogyo Co., Ltd. (72) Inventor Kei Kei Bamba 1-2-1, Marunouchi, Chiyoda-ku, Tokyo Sun (72) Inventor Toshishi Sawada 1-1-2 Marunouchi, Chiyoda-ku, Tokyo, Japan Nihon Kokan Co., Ltd. (72) Inventor Shinichi Endo 1-2-1, Marunouchi, Chiyoda-ku, Tokyo F-term (reference) 4D040 BB05 BB32 BB57 BB72 BB92

Claims (2)

[Claims] At least a part of the sediment in the sedimentation basin of the treated wastewater when removing phosphorus from the wastewater using an apparatus comprising at least a sedimentation basin, an anaerobic tank and an aerobic tank for the wastewater to be treated For removing phosphorus from wastewater, comprising crushing or grinding and supplying the anaerobic tank 2. An apparatus comprising at least a sedimentation basin, an anaerobic tank, and an aerobic tank for a wastewater to be treated, and a line for extracting sediment from the sedimentation tank, and an apparatus for crushing or grinding the extracted sediment. And a line for supplying the crushed material or the crushed material to an anaerobic tank.