JP2001286883A - Method and device for treating sewerage flowing into terminal disposal plant - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a treating device for sewerage flowing into a terminal disposal plant capable of progressing the treating reaction at the sewerage terminal disposal plant in a relatively short time and capable of economically obtaining the good water subjected to nitrogen removing treatment and phosphorus removing treatment and capable of operating with a reduced expense by simultaneously performing BOD treatment and at least one kind of nitrogen removing treatment and phosphorus removing treatment. SOLUTION: In the treating device, a biologically treating device for biologically treating the industrial waste water relatively high in a BOD concentration and relatively low in a nitrogen concentration and a phosphorus concentration at a plant generating the industrial waste water, an introducing means for introducing the industrial waste water treated at the biologically treating device to the sewerage terminal disposal plant and a means for introducing domestic waste water to the sewerage terminal disposal plant and for subjecting the domestic waste water to mixing treatment with the industrial waste water are provided. The biologically treating device of the industrial waste water at the plant generating the industrial waste water is relatively low in the removing capacity by oxidation of BOD, and the treated water obtained at the biologically treating device has relatively high BOD concentration releasable to the sewerage.

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 treating wastewater, and more particularly, to BOD removal treatment in treating wastewater flowing into a sewer final treatment plant, that is, wastewater mixed with industrial wastewater and domestic wastewater. In addition, the present invention relates to a processing method and a processing apparatus for performing a biological nitrogen removal treatment and a biological phosphorus removal treatment.

[0002]

2. Description of the Related Art Biological treatment techniques are widely used as a technique for removing sludge substances such as organic substances from wastewater, and the activated sludge method and its apparatus are typical examples.
By treating with activated sludge equipment, mainly BOD and SS can be removed from wastewater. That is,
At least a portion of the BOD is aerobically oxidatively decomposed in the aeration tank of the activated sludge process equipment. Also, at least a portion of the BOD is converted into microorganisms that are measured as SS,
The SS originally contained in the wastewater is settled and removed together with the SS generated as a result of the oxidation treatment of the BOD in the first settling tank and the last settling tank of the treatment facility.

[0003] In recent years, in order to prevent eutrophication of enclosed water areas, wastewater treatment techniques capable of removing not only BOD and SS but also nitrogen and phosphorus have been used. Examples of such techniques include a modified activated sludge nitrification liquid circulation method, an anaerobic-anoxic-aerobic activated sludge method, and an anaerobic-aerobic activated sludge method, which are modifications of the activated sludge method. .

[0004] Fig. 3 shows an example of a conventional wastewater treatment apparatus using a method called a modified activated sludge nitrification liquid circulation method. As shown in the figure, this wastewater treatment apparatus comprises a sedimentation basin 2, an aerobic tank 4, an anoxic tank 3, and a final sedimentation basin 7. An aeration device 5 is provided in the aerobic tank 4, and a reaction for oxidizing nitrogen compounds in wastewater to nitrate nitrogen or nitrite nitrogen (nitrification reaction) and other reactions are performed in the aerobic tank. 4 is performed. In the anoxic tank 3, a reaction for reducing nitrate nitrogen or nitrite nitrogen to nitrogen gas (denitrification reaction) and other reactions are performed.

[0005] Wastewater 1 is first introduced into the sedimentation basin 2,
Here, relatively large and heavy solids are removed and then introduced into the reaction tank. Nitrogen in the wastewater undergoes a nitrification reaction and a denitrification reaction, and is finally removed from the wastewater by being released into the atmosphere in the form of nitrogen gas. At least a part of the effluent of the aerobic tank 4 after being subjected to the nitrification treatment is circulated and returned to the anoxic tank 3 as a nitrification circulating liquid 6. In the final sedimentation basin 7, treated water 9 is obtained, and a part of the sedimentation sludge generated here is introduced into the oxygen-free tank 3 as returned sludge 8.

[0006] The denitrification reaction in the oxygen-free tank 3 is carried out by binding oxygen contained in nitric acid molecules or nitrous acid molecules to organic matter (B).
OD). This reaction requires a reducing agent, and organic matter in wastewater introduced into the oxygen-free tank 3 is used as the reducing agent. Further, this reaction proceeds under the condition where free oxygen does not exist, that is, under anoxic condition. BO
Organic matter in the wastewater measured as D etc. is removed in both the anoxic tank 3 and the aerobic tank 4, and SS is first removed in the sedimentation basin 2 and the final sedimentation basin 7.

The anaerobic-anoxic-aerobic activated sludge method or A
FIG. 4 shows an example of a wastewater treatment apparatus according to a conventional method called the 2O method. As shown in the figure, this wastewater treatment apparatus first comprises a sedimentation basin 2, an anaerobic tank 10, an oxygen-free tank 3, and an aerobic tank 4.
And the final sedimentation basin 7. In the anaerobic tank 10, a biological phosphorus release reaction in which the activated sludge releases intracellular phosphate ions into the wastewater, and other reactions are performed. In the anoxic tank 3, the activated sludge removes the phosphorus in the wastewater. Biological phosphorus uptake reaction to ingest acid ions into cells,
Denitrification and other reactions take place. An aeration device 5 is provided in the aerobic tank 4, and a biological phosphorus uptake reaction in which activated sludge takes up phosphate ions in wastewater into cells,
The nitrification reaction and other reactions are performed in the aerobic tank 4.

At least a part of the effluent of the aerobic tank 4 after being subjected to the nitrification treatment is circulated and returned to the anoxic tank 3 as a nitrification circulating liquid 6. A part of the settled sludge obtained in the final settling basin 7 is introduced into the anaerobic tank 10 as returned sludge 8. The phosphorus uptake of activated sludge in the anoxic and aerobic processes is greater than the phosphorus release in the anaerobic process, and the difference between this phosphorus intake and the phosphorus release corresponds to the amount of phosphorus removed from wastewater. I do.

The anaerobic-anoxic-aerobic activated sludge process apparatus shown in FIG. 4 performs a biological dephosphorization reaction and a denitrification reaction to remove phosphorus and nitrogen together with BOD and SS in wastewater. The removal processing is performed. Both the biological phosphorus release response and the biological phosphorus uptake response are organic (BO)
This is a reaction requiring D), and the phosphorus release reaction proceeds under the absence of free oxygen and bound oxygen, that is, under anaerobic conditions. For this reason, in the illustrated apparatus, the nitrification circulating liquid 6 is not introduced into the anaerobic tank 10. This is to prevent the bound oxygen contained in the nitric acid and nitrite molecules in the nitrification circulating liquid 6 from being introduced into the anaerobic tank 10 to suppress the phosphorus release reaction.

Although not shown in FIG. 4, by adding a coagulant such as an aluminum salt or an iron salt to, for example, an inflow portion or an outflow portion of the reaction tank, the biological dephosphorization treatment method and the physicochemical desorption method are performed. It is also possible to use an apparatus using the phosphorus treatment method in combination. Further, in the biological nitrification denitrification apparatus using the modified activated sludge nitrification liquid circulation method shown in FIG. 3, this physicochemical dephosphorization treatment method may be used in combination.

FIG. 5 shows an example of a wastewater treatment apparatus according to a conventional method called an anaerobic-aerobic activated sludge method. As shown in the figure, the apparatus mainly includes a first sedimentation basin 2, an anaerobic tank 10, an aerobic tank 4, and a final sedimentation basin 7. Anaerobic tank 1
At 0, a biological phosphorus release reaction in which activated sludge releases intracellular phosphate ions into wastewater, and other reactions are performed. A diffuser 5 is provided in the aerobic tank 4, and a biological phosphorus uptake reaction in which activated sludge takes up phosphate ions in wastewater into cells, and other reactions are performed in the aerobic tank 4. Done.

A part of the settled sludge obtained in the final settling basin 7 is introduced into the anaerobic tank 10 as returned sludge 8. 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.

The anaerobic-aerobic activated sludge treatment shown in FIG. 5 is for performing a biological dephosphorization reaction to remove phosphorus together with BOD and SS in wastewater. Although not shown in FIG. 5, there is a case where an apparatus using both a biological dephosphorization treatment method and a physical dephosphorization treatment method by adding a flocculant is used.

In the above-described apparatus shown in FIGS. 3 and 4, when the nitrification denitrification reaction is caused by using only floating organisms (activated sludge), the following problem occurs. That is, since the growth rate of nitrifying bacteria is smaller than the growth rate of BOD-removing bacteria and denitrifying bacteria, to maintain the concentration and activity of nitrifying bacteria in one activated sludge system,
It is necessary to increase the sludge age of activated sludge (retention time of sludge). As a result, the reactor must be large in order to retain a large amount of sludge in the reactor. In order to cope with such a problem, it has been proposed that a granular carrier is charged into at least a part of a reaction tank to cause the immobilized microorganism to perform a nitrification reaction. As a result, a technique of performing BOD and SS removal treatment, nitrification denitrification treatment, and in some cases, biological phosphorus removal treatment in a reaction tank having a total residence time of about 6 to 8 hours has recently been put to practical use. Has reached.

The method and apparatus used for treating industrial wastewater vary depending on the nature of the industrial wastewater, the treatment amount, the target treated water quality, and the like. Here, FIG. 6 shows an example of a conventional apparatus used for treating wastewater having a higher BOD concentration than nitrogen and phosphorus concentrations, such as food factory wastewater. In the illustrated treatment apparatus, the industrial wastewater 21 is temporarily stored in a wastewater storage tank 22 and, depending on the original property of the wastewater,
The drug is added. Specifically, a pH adjuster 26 for adjusting the pH to a level suitable for biological treatment or discharge of treated water in a later stage, a nitrogen-based agent 27 for supplying nitrogen, and a phosphorus for supplying phosphorus The system chemical 28 is added to the wastewater storage tank 22. With the addition of these drugs,
The properties of the wastewater are adjusted to those suitable for biological treatment such as activated sludge treatment at the subsequent stage, and the capacity is utilized to make the treatment amount uniform.

Thereafter, the wastewater is introduced into the aeration tank 23, where the BOD in the wastewater 21 is oxidized by mixing with the activated sludge 8 and utilizing oxygen in the air supplied through the diffuser 5. The sludge mixture that has been treated in the aeration tank 23 is introduced into a sedimentation basin 24, where it is separated into solid and liquid to obtain treated water 9 as supernatant water and sedimented sludge. Part of the settled sludge is returned to the aeration tank 23 as returned sludge 8, and the remaining part is pulled out as surplus sludge and treated and treated. Depending on the properties of the industrial wastewater and the like, in addition to the treatment facility shown in FIG. 6, a coagulation settling facility, a sand filtration facility, an activated carbon treatment facility, and the like may be provided.

FIG. 6 shows an example of the treatment of industrial wastewater by the activated sludge method. In the case where the wastewater to be treated contains almost no toxic substances such as cyan and heavy metals, the food industry It is often treated not only in wastewater but also in biological treatment equipment represented by the activated sludge method. This is because the operation cost of the biological treatment equipment is generally lower than that of the physicochemical treatment equipment such as the activated carbon adsorption method and the coagulation precipitation method.

When a sewer system is provided, household wastewater is basically discharged to a sewer pipe, treated at a sewer final treatment plant, and discharged to a river or a sea area.
On the other hand, with regard to industrial wastewater, generators treat the wastewater in the plant where it is generated and discharge it directly to rivers or sea areas, or discharge the wastewater from the plant to the sewer, and finally at the final treatment plant. After processing, it may be released to rivers or sea areas. An example of the relationship between the treatment of industrial wastewater and the sewer is schematically shown in FIG. In the figure, treated water A3 of plant A obtained by treating industrial wastewater A1 of plant A with treatment equipment A2 in plant A is discharged to a river or a sea area, and industrial wastewater B1 of plant B is converted to plant B. Processing equipment B
The treated water B3 of the factory B obtained by the treatment in Step 2 is discharged to the sewer.

When industrial wastewater is discharged to the sewer, the treatment function of the wastewater treatment plant may be affected depending on the amount and concentration of the wastewater. Upper limit of BOD and SS concentration etc.)
Is usually defined. The generated industrial wastewater may be discharged to the sewer as it is, or the wastewater may be discharged to the sewer after the producer processes the industrial wastewater as needed. For example, when the BOD of the wastewater received in the sewer is set to 300 mg / L or less, the BOD of the treated water is 300 mg in a factory that generates wastewater with a BOD concentration of about 600 mg / L.
/ L is treated after lower-grade treatment to a little less than / L, and the treated industrial wastewater is treated with domestic sewage and the like at a terminal treatment plant to reduce the BOD to 20 mg / L.
The following is the case where the water is discharged into a river.

In the example shown in FIG. 7, the industrial wastewater B1 of the factory B is discharged to the sewer after being treated by the treatment facility B2. In this case, the industrial wastewater treated water B3 of the factory B is
After being mixed with sewage C1 composed of domestic wastewater and the like, the sewage is treated in a sewage terminal treatment plant treatment facility C2, and the obtained sewage treated water C3 is discharged to a river or a sea area.

At present, most of the sewage treatment equipment C2 in FIG. 7 employs the standard activated sludge method. However, the activated sludge nitrification liquid circulation method described above, the anaerobic-anoxic-aerobic activated sludge method, and the anaerobic- Advanced treatment facilities using the gas-generated sludge method are gradually increasing.

[0022]

There are the following problems in performing sewage nitrogen removal by the biological nitrification and denitrification method. In other words, the sewage that has flowed into the final treatment plant is first subjected to solid pollutant removal treatment by a screen or first settling basin, so the wastewater first supplied to the denitrification process via the settling basin is dissolved. It will be composed mainly of pollutant pollutants. At this time, if the organic matter / nitrogen concentration ratio of the pollutants in the wastewater supplied to the denitrification step, particularly the soluble pollutants, is low, the progress of the denitrification reaction is hampered by the lack of organic substances (reducing agent). It becomes sufficient and the quality of treated water deteriorates.

In the biological phosphorus removal treatment, an organic substance is required for the anaerobic reaction and the aerobic reaction. Therefore, when the concentration of organic matter (BOD) flowing into the reaction tank is insufficient compared with the concentration of phosphorus, the phosphorus release reaction or the phosphorus uptake reaction or both become insufficient, and the treatment is performed in the same manner as described above. There is a problem that water quality deteriorates.

According to the inventor's experimental findings on the treatment of sewage, the total nitrogen concentration in the sewage is 20 to 30 mg.
/ L, and when the BOD concentration / nitrogen concentration ratio is higher than about 3.1, the nitrogen concentration of the biological nitrogen removal treated water is reduced to 7 m.
It is relatively easy to set the g / L or less. However, when the BOD concentration / nitrogen concentration ratio is lower than about 2.8, the nitrogen concentration of the biological nitrogen removal treated water is reduced to 7 mg / L.
It is relatively difficult to:

That is, when the ratio of BOD in the wastewater is high, there is a disadvantage that the nitrification reaction in the biological nitrogen removal reaction proceeds at a relatively low speed, but there is a sufficient amount of organic substances used in the denitrification reaction. It is advantageous in that it does. For this reason, if the nitrification reaction is sufficiently generated, it is possible to finally obtain treated water having a low nitrogen concentration relatively easily. The nitrification reaction when the ratio of BOD in the wastewater is high can be promoted by using, for example, a nitrifying bacteria-immobilized carrier. Alternatively, even if a means of increasing the residence time of the nitrification reaction tank is adopted,
The nitrification reaction can be promoted. When these means are used, care must be taken to use a carrier that has little wear and requires little replenishment, and the operating cost is greatly increased as compared with the case where only BOD removal processing is performed. , And good treated water can be obtained.

On the other hand, when the ratio of BOD in the wastewater is low, there is an advantage that the nitrification reaction in the biological nitrogen removal reaction proceeds at a relatively high speed, but the biological nitrogen removal reaction Of these, the denitrification reaction proceeds at a relatively low speed. Further, the reducing agent for nitrate nitrogen or nitrite nitrogen becomes stoichiometrically short. As a result, the removal of nitrate nitrogen or nitrite nitrogen becomes insufficient,
A relatively high concentration of nitrogen often remained in the final treated water. When the ratio of BOD in the sewage flowing into the terminal treatment plant is low, it is difficult to obtain good treated water even after performing advanced treatment for the purpose of nitrogen removal treatment, and this is a serious problem.

When the ratio of BOD in the sewage flowing into the terminal treatment plant is low, it is difficult to obtain good treated water for the same reason as described above even when performing advanced treatment for removing phosphorus. Was.

As described above, one of the major causes of the composition of the sewage flowing into the terminal treatment plant having a low ratio of organic matter (BOD) is the origin and composition of the sewage. For example, so-called household wastewater, which is a combination of toilet wastewater and kitchen wastewater, has a ratio of BOD concentration to nitrogen concentration of 3 to 1 inside and outside. In contrast, for example,
Industrial wastewater such as bean paste wastewater and alcohol-based brewery wastewater is BO
The ratio of D is very high, and the wastewater (ammonium) and leather production wastewater generated during coke production are industrial wastewater with a very high nitrogen ratio. Municipal sewage generally contains a large amount of domestic wastewater, but often contains industrial wastewater. Depending on the type and mixing ratio of the industrial wastewater, the BOD concentration / nitrogen concentration ratio of the sewage mixed with the industrial wastewater becomes low, and when performing nitrogen removal treatment or phosphorus removal treatment at the terminal treatment plant, good treated water can be obtained. It was difficult to obtain.

[0029] Industrial wastewater having an extremely high BOD ratio, such as the above-mentioned bean-making wastewater or alcohol-based brewing wastewater, is highly treated by activated sludge treatment equipment or the like in the plant, so that the treated water becomes a BOD ratio. Is low. Therefore, even industrial wastewater that originally has a high BOD ratio,
When the treated water after the relatively high-grade treatment, that is, the treatment with a high BOD removal rate, is discharged to the sewer, the following problem occurs. Specifically, the BOD ratio of the wastewater received by the sewage final treatment plant, that is, the wastewater mixed with industrial wastewater and domestic wastewater, is a sufficiently high ratio suitable for performing the nitrogen removal treatment or the phosphorus removal treatment. Did not become.

Further, in general, in activated sludge treatment mainly for BOD removal treatment, the composition of wastewater to be treated is preferably BOD: nitrogen: phosphorus = about 100: 5: 1. Therefore, in order to perform good BOD removal treatment on industrial wastewater with a high BOD ratio, ammonium sulfate, ammonium phosphate, and phosphoric acid are artificially added to compensate for nitrogen and phosphorus that are insufficient only with the components in the original wastewater. A technique has been used in which activated sludge is treated after being added to wastewater. Treated water from which BOD has been satisfactorily removed by relatively increasing the concentration of nitrogen or phosphorus,
The OD concentration is relatively low and the nitrogen or phosphorus concentration is relatively high. When the treated wastewater treated water is discharged to the sewer, the terminal treatment plant influent water has a sufficiently high BOD ratio suitable for performing the nitrogen removal treatment or the phosphorus removal treatment. It was not what it was.

When at least one of the nitrogen removal treatment and the phosphorus removal treatment is performed simultaneously with the BOD removal treatment,
When the composition of the wastewater to be treated has a small BOD concentration / nitrogen concentration ratio or BOD concentration / phosphorus concentration ratio, it is possible to obtain treated water having a target water quality due to a shortage of BOD in the wastewater. It can be difficult. In order to cope with such a problem, an organic chemical such as methanol is supplied to the denitrification step or the biological phosphorus removal treatment step together with the wastewater to compensate for the shortage of the organic matter concentration in the wastewater, thereby obtaining a good nitrogen removal treatment water or phosphorus. A method of obtaining the treated water for removal has been used. However, when an organic chemical such as methanol flows into the denitrification step or the biological phosphorus removal treatment step, the cost of the chemical is increased, thereby increasing the operating cost. In addition, depending on the type and concentration, equipment for storing and supplying a large amount of dangerous organic drugs is required, which increases equipment costs, and requires a high level of safety considerations for equipment operation management. The problem was that it would happen.

In wastewater subject to biological treatment, BO
The condition that the D concentration / nitrogen concentration ratio or the BOD concentration / phosphorus concentration ratio is small has not been a particular problem in conventional techniques such as the standard activated sludge method. In the conventional treatment technology, wastewater having a small BOD concentration / nitrogen concentration ratio or a small BOD concentration / phosphorus concentration ratio is mainly subjected to aerobic treatment to remove BOD and SS satisfactorily. This is because it was not a removal target.

The present invention relates to a method for treating influent water at a terminal sewage treatment plant which performs at least one of nitrogen removal treatment and phosphorus removal treatment at the same time as BOD removal treatment. Further, it is an object of the present invention to provide a method for treating influent water at a sewer terminal treatment plant that can economically obtain good nitrogen-removed treated water or phosphorus-removed treated water and reduce the burden of operating costs.

The present invention also relates to an apparatus for treating influent water at a terminal sewage treatment plant which performs at least one of nitrogen removal treatment and phosphorus removal treatment at the same time as BOD removal treatment. It is an object of the present invention to provide an apparatus for treating inflow water of a sewer terminal treatment plant that can economically obtain good nitrogen-removed treated water or phosphorus-removed treated water and can be operated at a reduced cost. .

[0035]

In order to solve the above-mentioned problems, the present invention comprises a step of treating in an anaerobic tank or an anoxic tank at least in a part of a reaction tank, and comprises a biological nitrogen removal treatment and a biological treatment. A method for treating influent from a sewer terminal treatment plant that performs at least one of biological phosphorus removal treatment, comprising:
A step of removing BOD by biologically treating industrial wastewater having a relatively high concentration and a relatively low concentration of nitrogen or phosphorus in a factory where the industrial wastewater is generated, and introducing the industrial wastewater after the removal of the BOD to a wastewater treatment plant. And a step of introducing domestic wastewater to the final sewage treatment plant and mixing and treating the wastewater with the industrial wastewater. The biological treatment of the industrial wastewater in the industrial wastewater generation plant has a capability of removing and oxidizing BOD. The method provides a method for treating influent water at an end-of-life sewage treatment plant, characterized in that treated water having a BOD concentration close to the upper limit that can be discharged to the sewage is obtained in this step.

In addition, the present invention provides an anaerobic tank or an anoxic tank in at least a part of the reaction tank, wherein at least one of the biological nitrogen removal treatment and the biological phosphorus removal treatment is performed. A biological treatment apparatus for biologically treating industrial wastewater having a relatively high BOD concentration and a relatively low nitrogen concentration and a low phosphorus concentration in a factory where the industrial wastewater is generated. An industrial wastewater, an introduction means for introducing the wastewater into a wastewater treatment plant, and a means for introducing living wastewater to the wastewater wastewater treatment plant and mixing and treating the wastewater with the industrial wastewater; Wastewater biological treatment equipment is B
Oxidation removal capacity of OD is comparatively low, and the treated water obtained by this biological treatment apparatus has a BO close to the upper limit that can be discharged to the sewer.
An apparatus for treating influent of a sewer terminal treatment plant having a D concentration.

[0037] In the method for treating the influent of a sewer final treatment plant according to the present invention, at least one of a nitrogen compound and a phosphorus compound during the biological treatment of the industrial wastewater in the industrial wastewater generation plant. It is preferable that at least one selected from the group consisting of: limiting addition to the industrial wastewater; limiting the return sludge flow rate; limiting the effective capacity of the aeration tank; and limiting the degree of the temperature adjustment operation.

In the apparatus for treating influent water at a wastewater treatment plant according to the present invention, the biological treatment apparatus for biologically treating the industrial wastewater at the industrial wastewater generation plant may include a means for limiting aeration; at least one of a nitrogen compound and a phosphorus compound. At least one means selected from a means for restrictively adding one kind to the industrial wastewater, a means for restricting the return sludge flow rate, a means for restricting the effective capacity of the aeration tank, and a means for restricting the degree of temperature control operation It is preferable to provide

[0039] In the present invention, the influent of the sewer final treatment plant refers to wastewater flowing into the sewer final treatment plant, that is, mixed wastewater of industrial wastewater and domestic wastewater.

[0040]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a method and an apparatus for treating influent of a sewer terminal treatment plant according to the present invention will be described with reference to the drawings.

FIG. 1 is a schematic diagram showing an example of an apparatus for treating industrial wastewater, which constitutes a part of an apparatus for treating influent water at a terminal sewage treatment plant according to the present invention. In the illustrated device, the industrial wastewater 21 is first stored in a wastewater storage tank 22. Here, according to the original properties of the wastewater, a pH adjuster 26 for adjusting to a pH suitable for biological treatment in the subsequent stage and discharge of the treated water is added, and the treatment amount can be made uniform. And Thereafter, the wastewater is introduced into the activated sludge treatment facility including the aeration tank 23 and the sedimentation tank 25, and mixed with the returned sludge 8 while utilizing the oxygen in the air supplied through the air diffuser 5 to remove the wastewater from the wastewater 21. The BOD is oxidized. The sludge mixed solution that has been treated in the aeration tank 23 is introduced into a sedimentation basin 24, where it is separated into solid and liquid to obtain treated water 9 as supernatant water and sedimented sludge. A part of the settled sludge is returned to the aeration tank 23 as returned sludge 8, and the remaining part is pulled out as surplus sludge and treated and treated.

One of the differences between the apparatus of the present invention shown in FIG. 1 and the conventional apparatus shown in FIG. 6 is that a nitrogen-based chemical 27 and a phosphorus-based chemical are supplied to the wastewater storage tank 22 in order to adjust the properties of the wastewater. That is, there is no addition line for the medicine 28.

It is an object of the present invention to perform nitrogen removal treatment or phosphorus removal treatment at a wastewater treatment plant having a relatively high BOD concentration at a wastewater treatment plant to thereby remove BOD in the wastewater wastewater. To obtain good treated water by effectively utilizing the water. In order to achieve this, industrial wastewater having a relatively high BOD concentration is treated as needed, and the BOD concentration of the treated water at the time of discharging the treated water to the sewer is set to the upper limit of discharge to the sewer. The concentration is close.

As one of means for achieving the object of the present invention as described above, as shown in FIG. 1, the wastewater is supplied to a factory without adding a nitrogen-based agent 27 and a phosphorus-based agent 28. To obtain industrial wastewater with a relatively high BOD concentration and discharge it to the sewer. In this case, the BOD concentration / nitrogen concentration ratio of the industrial wastewater at the time of flowing into the biological treatment facility in the factory is greater than 100/5, or BO
It is preferred that the D concentration / phosphorus concentration ratio is greater than 100/1.

However, depending on the original properties of the industrial wastewater, if the nitrogen-based agent 27 or the phosphate-based agent 28 is treated without addition, the BOD concentration / nitrogen concentration ratio or the BOD concentration
In some cases, the concentration / phosphoric acid concentration ratio becomes too large to obtain treated water having a BOD concentration that can be discharged to the sewer. In this case, it is desirable to add a small amount of the nitrogen-based agent 27 and / or the phosphate-based agent 28 to the industrial wastewater and remove the BOD to such an extent that the BOD can be released to the sewer.

In the treatment technique of the present invention, the nitrogen-based drug 2
Whether or not to add 7 or the phosphorus-based agent 28, the amount of addition of such agent can be determined in consideration of the nature and amount of industrial wastewater, the acceptance standard for sewerage, and the like. . In any case, the BO at the time the industrial wastewater flows into the biological treatment facility in the factory
Whether the D concentration / nitrogen concentration ratio is greater than 100/5, or the BOD concentration / phosphorus concentration ratio is greater than 100/1;
Alternatively, both are preferable.

Even when the operation is performed by adding these chemicals due to the high ratio of the original BOD concentration in the industrial wastewater, the conventional technology for treating mainly the high-level removal of BOD is not used. The amount of addition is BOD concentration /
A nitrogen concentration ratio of about 100/5 or a BOD concentration / phosphorus concentration ratio of about 100/1 has been targeted. On the other hand, in the present invention, these concentration ratios are made higher, and the amount of drug added is made small. In the present invention, a case where such a drug is not added and a case where a relatively small amount is added are defined as restricted addition in the present invention.

In the treatment of industrial wastewater, nitrogen-based chemicals 27
Alternatively, by limiting the addition of the phosphorus-based agent 28, the agent cost is reduced from the cost required in the conventional activated sludge treatment. For this reason, there is an advantage that the burden on the operating cost of the treatment facility is reduced for the industrial wastewater producer.

As described above, the purpose of the present invention is to make the BOD concentration of the influent of the sewer final treatment plant relatively high, and perform the nitrogen removal treatment or the phosphorus removal treatment at the sewer final treatment plant. Another object of the present invention is to obtain good treated water by effectively utilizing the BOD flowing into a sewer final treatment plant. In order to achieve this, industrial wastewater having a relatively high BOD concentration is treated as needed, and the BOD concentration of the treated water at the time of discharging the treated water to the sewer is set to the upper limit of discharge to the sewer. The concentration is close.

Therefore, the biological treatment device for industrial wastewater constituting the treatment device for the influent of the sewer terminal treatment plant according to the present invention has a relatively small BOD oxidizing / removing ability and a BOD which is close to the upper limit of the possible discharge to the sewer. It must be able to obtain a concentration of treated water. In the activated sludge treatment facility for industrial wastewater shown in FIG.
Aeration / reaction by limiting the flow rate of the returned sludge 30 by limiting the amount of oxygen supplied to the reactor to reduce the activated sludge concentration in the aeration tank 23, or by limiting the effective capacity of the aeration tank 23 This can be achieved by reducing the time associated with When a heating or cooling operation is performed to optimize the reaction temperature, the degree of the temperature adjustment operation may be limited. In particular, the combined use of these means is effective in reducing the BOD oxidative removal treatment capacity in an industrial wastewater treatment apparatus.

Further, it is possible to combine these means with the above-mentioned means of treating by limiting addition of the nitrogen-based agent 27 or the phosphorus-based agent 28, and this method is effective.

In the biological treatment facility for industrial wastewater of the present invention, it is possible to use a limited aeration and, in an extreme case, no aeration. However, depending on the time during which the industrial wastewater to be treated stays in the storage tank 22 and the aeration tank 23, the properties of the industrial wastewater, and the like, the organic matter contained in the industrial wastewater may decay and generate an odor. For this reason, a small amount of aeration may be required to prevent the progress of decay. Among the means of this limited aeration, with regard to blowing air into the aeration tank, reduce the air flow rate,
Alternatively, not only means for reducing the amount of blown air by intermittent air supply but also the following means are included. Specifically, for example, a means for using a diffuser system having a relatively low oxygen dissolving efficiency, such as using a coarse bubble type diffuser or reducing the diffused water depth, to blow air into the aeration tank. It is. When the bubble diameter due to the blown air is large, the gas-liquid contact area per unit blown air amount is small, and when the diffused water depth is small, the gas-liquid contact time is short and the oxygen dissolution efficiency to the liquid side is reduced. Decrease. Thus, in any case, as a result of limiting the amount of oxygen used for the biological oxidation treatment, the capacity of the industrial wastewater treatment apparatus for removing and oxidizing the BOD is reduced.

In the present invention, when the flow rate of the return sludge 8 of the facility for biologically treating the industrial wastewater is limited, the return can be made non-returned in an extreme case. in this case,
Since the activated sludge (microorganism) concentration in the aeration tank 23 is extremely low, the function as biological treatment is greatly reduced. Usually, the activated sludge concentration (MLSS concentration) in the aeration tank of the activated sludge treatment equipment for industrial wastewater treatment is 20%.
The operation is performed at about 00 to 5000 mg / L. However, if the MLSS concentration is reduced by lowering the return flow rate, the capacity of the activated sludge treatment equipment to oxidize and remove the BOD is reduced by the ML in the aeration tank.
It decreases almost in proportion to the SS concentration. In order to reduce the flow rate of the returned sludge, the flow rate of the sludge return pump can be reduced, and the operation time of the sludge return pump can be limited to perform intermittent operation.

In the present invention, when the effective capacity of the aeration tank 23 of the facility for biologically treating industrial wastewater is limited, in an extreme case, the operation can be performed by bypassing the aeration tank 23. When only a part of the aeration tank 23 is used, the part of the aeration tank 23 is buried and killed, or industrial wastewater is introduced in the middle of the flow-down type multi-stage aeration tank, or the outflow level of the aeration tank 23 is lowered to lower the effective water depth. For example, means such as

In the industrial wastewater treatment equipment, when the effective capacity of the aeration tank 23 is relatively small, when the temperature of the generated wastewater is low, for example, about 0 ° C., when the industrial wastewater treatment equipment is in a cold region, etc. A technique is used in which at least one of the wastewater storage tank 22 and the aeration tank 23 is heated with steam or the like to bring the temperature of the aeration tank 23 closer to a temperature effective for biological treatment, for example, about 30 ° C. ing.

On the other hand, the organic matter (BO
When the concentration of D) is extremely high, for example, 20,000 mg / L or more, heat is generated due to the biological oxidation reaction in the aeration tank 23, and the water temperature becomes too high, so that the wastewater treatment efficiency may decrease. As a countermeasure, aeration tank 23
Is cooled, and the temperature of the aeration tank is approached to a condition suitable for biological treatment.

In the case described above, the activity of the microorganisms can be reduced by limiting the degree of the temperature adjustment operation so that the temperature of the wastewater treatment reaction deviates from a suitable range. As a result, it is possible to reduce the oxidation treatment capacity of the BOD of the wastewater treatment device.

Among the above means, the amount of air (oxygen) introduced into the aeration tank 23 is reduced, or
Employing a means of reducing the flow rate of zero to reduce the activated sludge concentration in the aeration tank 23 leads to a reduction in the load on the aeration blower or the load on the sludge return pump. For this reason, the motor power is often reduced and the operating cost can be reduced. In particular, when a plurality of blowers or pumps are installed and the number of operating units can be reduced, a remarkable economic effect can be expected. In addition, even when a diffuser system having a relatively low oxygen dissolving efficiency is used, the airflow resistance when air is blown into the aeration tank through the diffuser is reduced, so that the power of the blower can often be reduced.

In ordinary biological treatment, the aeration power is relatively large. For this reason, the operating cost is significantly reduced by adopting a means of performing limited aeration, that is, reducing the amount of aerated air or using a diffuser system having a relatively small oxygen dissolving efficiency, among the above-mentioned means. In many cases, such an effect can be obtained.

The above-mentioned means relating to the treatment of industrial wastewater include:
The present invention can be applied not only to new industrial wastewater treatment equipment, but also to the remodeling or improvement operation of existing equipment. When applying the present invention to existing equipment for industrial wastewater treatment,
It is preferable to employ the following means. Specifically, it is a means of reducing the amount of aeration air, reducing the sludge return flow rate, reducing the amount of chemical added, or reducing the heating temperature. In the case of employing such means, it is often possible to cope with it only by changing the operating conditions without modifying the existing equipment.

On the other hand, when using an aeration system having a low oxygen dissolving efficiency or employing means for reducing the effective capacity of an aeration tank, it is often necessary to remodel a part of the processing apparatus.

By performing such operations and treatments, the industrial wastewater to be treated to effectively use the BOD for the nitrogen removal treatment or the phosphorus removal treatment of the sewage includes bean-making wastewater, alcohol-based brewing wastewater, and so on. Food wastewater such as noodle wastewater and bento factory wastewater is common. Furthermore, any industrial wastewater that is free of toxic substances, is suitable for biological treatment, and has a relatively high BOD can be used as a treatment target here.

Depending on the properties of the industrial wastewater to be treated by the method of the present invention, it is possible to provide a coagulation / sedimentation facility, a sand filtration facility, an activated carbon treatment facility, etc. in addition to the treatment facility shown in FIG.

FIG. 2 shows an example of an apparatus for treating inflow water of a sewer terminal treatment plant according to the present invention. In the same drawing, treated water A3 of Plant A obtained by treating industrial wastewater A1 of Plant A with treatment equipment A2 of Plant A is discharged to the sewer. Further, treated water B3 obtained by treating the industrial wastewater B1 of the factory B at the treatment facility B2 of the factory B is also discharged to the sewer. The treated water A3 and the treated water B3 are mixed with sewage C1 composed of domestic wastewater and the like, and then treated by a sewage advanced treatment facility (end treatment plant advanced treatment facility) C4, and the obtained treated water C3 is supplied to a river or sea area. Etc. will be released.

The apparatus for treating industrial wastewater (A2 and B2) shown in FIG. 1 obtains treated water having a BOD concentration close to the upper limit of sewerage discharge using the means described with reference to FIG. And Thereby, the BOD concentration in the sewage flowing into the advanced sewage treatment plant C4 can be increased.

Further, the advanced treatment equipment C4 of the sewage final treatment plant in the same figure is the modified sludge nitrification liquid circulation method or the anaerobic-anoxic-aerobic activated sludge method as described in FIGS. 3, 4 and 5. And an advanced anaerobic-aerobic activated sludge process, which performs at least one of biological nitrogen removal treatment and biological phosphorus removal treatment at the same time as biological BOD removal treatment. Since sewage having a high BOD concentration ratio flows into the terminal treatment plant, good treated water can be obtained when performing nitrogen removal treatment or phosphorus removal treatment. Of course, advanced treatment equipment C
As for No. 4, a reactor in which a carrier is contained in at least a part of the reaction tank equipment may be used, or a reactor using a physicochemical phosphorus removal treatment method may be used. Further, a combination of other processing techniques such as sand filtration may be used.

FIG. 2 showing the present invention is shown in FIG.
The difference is that the industrial wastewater treatment water A3 of Factory A is discharged directly to a river or sea area in FIG.
In FIG. 2, this is the point that is discharged to the sewer. However, the present invention is not limited to the point that the industrial wastewater that has been conventionally discharged directly to a river or a sea area is changed to be discharged to a sewer. For example, BOD of industrial wastewater treated water that has been discharged to the sewer
The effect can be sufficiently obtained only by performing the treatment to increase the value.

By using the present invention, the BO in the sewage flowing into the wastewater treatment plant at the time of performing the biological nitrogen removal treatment or the biological phosphorus removal treatment at the wastewater treatment plant.
The ratio of D concentration can be increased. Therefore, it is possible to obtain good sewage advanced treated water by effectively utilizing the BOD in the industrial wastewater.

[0069]

Now, the present invention will be described in further detail with reference to specific examples.

As shown in FIG. 4, a 1.2 m ³ / day treatment was carried out using two sets of experimental devices based on the anaerobic-anoxic-aerobic method (hereinafter referred to as first and second series). A sewage treatment experiment was carried out by volume. However, no settling basin was initially installed in each group, and the overflow of the first settling basin collected from the sewage treatment plant was temporarily stored in the sewage storage tank and introduced into the reaction tank. In addition, oil-water separation treated water (wastewater before aerated biological treatment) of wastewater from a bento manufacturing plant was temporarily stored in an industrial wastewater storage tank and used for the experiment.

The test sewage and the test industrial wastewater were collected from the site every two to three days and replenished to their respective storage tanks. In the first series, the sewage in the sewage storage tank was transported by a pump to be supplied directly above the surface of the anaerobic tank, and industrial wastewater was similarly supplied to the anaerobic tank at a flow rate of 1/5 of the sewage flow rate. On the other hand, in the second series, only sewage was similarly supplied to the anaerobic tank. The total amount of wastewater introduced into the anaerobic tank was set to be equal in each series. The first series is an embodiment of the present invention because it uses the same technology as the present invention in principle.

In each of the systems, the residence time of the anaerobic tank was 1 hour, the residence time of the oxygen-free tank was 4 hours, the residence time of the aerobic tank was 3 hours, and the inner diameter of the aerobic tank was 3 mm and the outer diameter was 4 m.
A hollow carrier made of polypropylene having a length of 5 mm and a length of 5 mm was accommodated so that its apparent capacity was 15% of the capacity of the aerobic tank.
The residence time of the sedimentation basin corresponding to the final sedimentation basin was 2.5 hours.

The MLSS concentration in the reaction tank was 2000 to 2
It was controlled to be 300 mg / L. In order to prevent the amount of nitrate nitrogen and nitrite nitrogen returned from the aerobic tank to the anoxic tank from becoming a control factor of the denitrification reaction, the sum of the return sludge flow rate and the nitrification circulating liquid flow rate is The ratio to the wastewater flow rate, that is, the circulation ratio, was operated at 400% in each series. In each series, the mechanical stirring conditions in the anaerobic tank and the oxygen-free tank and the aeration conditions in the aerobic tank were the same, and the DO in the aerobic tank was maintained at 3 mg / L or more. The sewage treatment was performed while controlling the water temperature during the experiment at 16 to 18 ° C.

After a two-month acclimatization period, five analyzes were performed to determine the p-value for raw water (with a mixing ratio of sewage and industrial wastewater of 5: 1) and treated water in the first series.
H, SS, BOD, TN and TP were measured. Raw water (only sewage) and treated water in the second series were measured in the same manner, and the minimum and maximum values of the obtained analysis data are summarized in Table 1 below.

[0075]

[Table 1]

As shown in Table 1, when comparing the first series of raw water with the second series of raw water, the BOD and SS of the first series of raw water using the same technology as the present invention in principle are as follows:
Higher than those of the second series, pH, TN and T-
Regarding P, there was no significant difference between the two. That is, the BOD concentration in the raw water in the first series /
The nitrogen concentration ratio and the BOD concentration / phosphorus concentration ratio could be higher than those in the second series.

A comparison between the first series of treated water and the second series of treated water shows that BOD and SS are almost the same. However, the nitrogen concentration and the phosphorus concentration of the treated water of the first series using the same technology as the present invention in principle are the second concentration.
It was lower than that of the treated water of the series, and the treated water of the first series was better.

From the results of this example, it was found that by introducing BOD derived from industrial wastewater into sewage and increasing the BOD concentration ratio of raw water at the time of advanced sewage treatment, good nitrogen removal treated water and phosphorus can be obtained. It became clear that water for removal treatment was obtained.

[0079]

As described above, according to the present invention, B
A method for treating influent water at a wastewater treatment plant that performs at least one of a nitrogen removal treatment and a phosphorus removal treatment at the same time as an OD removal treatment. Provided is a method for treating influent water at a sewer terminal treatment plant that can economically obtain water or treated water for removing phosphorus and can reduce the burden on operating costs. Further, according to the present invention, there is provided an apparatus for treating influent of a sewer final treatment plant which performs at least one of nitrogen removal treatment and phosphorus removal treatment at the same time as BOD removal treatment. The present invention provides an apparatus for treating influent of a sewer terminal treatment plant that can economically obtain good nitrogen-removed treated water or phosphorus-removed treated water and can be operated at a reduced cost.

By using the present invention, when performing a biological nitrogen removal treatment or a biological phosphorus removal treatment in a wastewater treatment plant, a stoichiometric reaction for the denitrification reaction or the biological phosphorus removal reaction is performed. Organic matter can be supplied. Therefore, the reaction rates of the denitrification reaction and the biological phosphorus removal reaction in the terminal treatment plant are increased, and good treated water can be obtained in a relatively short time treatment.

Further, according to the present invention, since the necessity of adding an organic chemical such as methanol can be reduced, the operating cost in the terminal treatment plant can be reduced.

By using the present invention, it is possible to reduce the amount of aeration air, the necessity of adding nitrogen compounds and phosphorus compounds, and the degree of temperature adjustment in the treatment of industrial wastewater. It is also effective in reducing operating costs in the field, and its industrial value is great.

[Brief description of the drawings]

FIG. 1 is a schematic diagram illustrating a configuration of an example of an industrial wastewater treatment apparatus according to the present invention.

FIG. 2 is a schematic diagram showing the relationship between industrial wastewater treatment and sewage equipment according to the present invention.

FIG. 3 is a schematic diagram illustrating a configuration of a conventional wastewater treatment apparatus.

FIG. 4 is a schematic diagram illustrating a configuration of a conventional wastewater treatment apparatus.

FIG. 5 is a schematic diagram illustrating a configuration of a conventional wastewater treatment apparatus.

FIG. 6 is a schematic diagram illustrating a configuration of a conventional wastewater treatment apparatus.

FIG. 7 is a schematic diagram showing a relationship between a conventional wastewater treatment apparatus and a sewage system.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Waste water 2 ... First sedimentation basin 3 ... Anoxic tank (denitrification tank) 4 ... Aerobic tank (nitrification tank) 5 ... Aeration device 6 ... Nitrification circulating fluid 7 ... Final sedimentation basin 8 ... Returned sludge 9 ... Treatment water 10 ... Anaerobic tank 21 ... Industrial wastewater 22 ... Wastewater storage tank 23 ... Aeration tank 24 ... Settling basin 26 ... pH adjuster 27 ... Nitrogen-based chemical 28 ... Phosphorus-based chemical A1 ... A factory industrial wastewater A2 ... A factory industrial wastewater treatment Facilities A3: Industrial wastewater treatment water at Plant A B1 ... Industrial wastewater treatment at Plant B B2 ... Industrial wastewater treatment plant at Plant B B3 ... Treatment treatment of industrial wastewater at Plant B C1 ... Sewage C2 ... Sewage treatment plant treatment plant C3 ... Sewage Treated water C4… Sewage treatment plant advanced treatment plant advanced treatment equipment

 ──────────────────────────────────────────────────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: Shinichi Endo 1-2-1, Marunouchi, Chiyoda-ku, Tokyo Japan Nippon Steel Pipe Co., Ltd. (72) Inventor: Masahisa Tanabe 1-2-1, Marunouchi, Chiyoda-ku, Tokyo Japan F term in the company (reference) 4D028 AB00 AB03 BC22 BD01 CA09 CA11 CB01 4D040 BB05 BB32 BB42 BB52 BB72 BB82 DD03 DD18

Claims (4)

[Claims] Claims: 1. An influent from a sewer terminal treatment plant that has at least a part of a reaction tank having a step of treating in an anaerobic tank or an anoxic tank and performs at least one of biological nitrogen removal treatment and biological phosphorus removal treatment. A method of removing BOD by biologically treating an industrial wastewater having a relatively high BOD concentration and a relatively low concentration of nitrogen or phosphorus in a plant for generating the industrial wastewater, wherein the BOD is removed. A step of introducing wastewater to a sewage terminal treatment plant, and a step of introducing living wastewater to the sewage terminal treatment plant and mixing and processing the industrial wastewater; The treatment is performed under the condition that the BOD has a relatively low oxidizing and removing ability, and treated water having a BOD concentration close to the upper limit that can be discharged to the sewer is obtained in this step. Treatment method for influent water at the terminal water treatment plant. 2. The process of subjecting said industrial wastewater to biological treatment in a plant where said industrial wastewater is generated, wherein a limiting aeration treatment; a limiting addition of at least one nitrogen compound and a phosphorus compound to said industrial wastewater; The method according to claim 1, wherein at least one selected from the group consisting of: limiting; limiting the effective capacity of the aeration tank; and limiting the degree of the temperature adjustment operation is performed. 3. An apparatus for treating influent water from a sewage terminal treatment plant which has an anaerobic tank or an anoxic tank in at least a part of a reaction tank and performs at least one of a biological nitrogen removal treatment and a biological phosphorus removal treatment. A biological treatment apparatus for biologically treating industrial wastewater having a relatively high BOD concentration and a relatively low nitrogen concentration and phosphorus concentration at a plant where the industrial wastewater is generated, the industrial wastewater treated by the biological treatment apparatus; An introduction means for introducing the wastewater to a wastewater treatment plant, and a means for introducing a living wastewater to the wastewater treatment plant, and mixing and treating the wastewater with the industrial wastewater. The treatment apparatus has a relatively low BOD oxidative removal ability, and the treated water obtained by the biological treatment apparatus has a BOD concentration close to an upper limit that can be discharged to a sewer. Wastewater treatment plant inflow water treatment equipment. 4. A biological treatment apparatus for biologically treating the industrial wastewater at a factory where the industrial wastewater is generated, the biological treatment apparatus comprising: a limiting aeration means; a means for restrictively adding at least one of a nitrogen compound and a phosphorus compound to the industrial wastewater; 4. The apparatus according to claim 3, further comprising at least one means selected from a means for restricting a return sludge flow rate, a means for restricting an effective capacity of an aeration tank, and a means for restricting a degree of a temperature adjusting operation. Wastewater treatment plant inflow water treatment equipment.